Keeping the electric power grid reliable and affordable has become a “critical challenge for the nation,” says a report by Grid Strategies and The Brattle Group.

Numerous challenges at various stages of the interconnection process delay the entry of new utility-scale generators, which are mostly low-cost renewables, “significantly” raising consumer costs and putting system reliability “at risk” as electricity demand rises, the report says.

Nationwide, 2600 GW of generating projects await interconnection studies, including 1100 GW of solar and 1000 GW of storage, some of which is co-located with solar.

Although the Federal Energy Regulatory Commission’s (FERC’s) Order No. 2023 on interconnection reforms issued last year “is helpful,” the report says that additional reforms are “urgently needed.”

The report comes weeks before a FERC workshop on “Innovations and Efficiencies in Generator Interconnection,” and was commissioned by Advanced Energy United and the Solar and Storage Industries Institute.

Proposed reforms range “across many aspects” of the interconnection process.

The first of four broad reform proposals is to create an “entry fee” process in which generators with ready-to-develop projects would pay a fee to gain access to transmission capacity that is already planned or will soon become available due to generator retirements.

A second set of reforms would implement a fast-track process to utilize planned or newly available transmission capacity, enabling resources that can use such available capacity and have paid the entry fee to bypass “time-consuming” cluster study processes designed to develop transmission solutions.

A third set of reforms would optimize the interconnection study process. One measure would enable project developers to select an energy-only interconnection option known as “connect and manage.” Another would direct transmission providers to evaluate all technologies that can “rapidly expand available headroom on transmission systems,” such as grid-enhancing technologies and advanced conductors. Other measures would use automation to expedite interconnection studies, improve alignment of interconnection study processes within and across systems, and establish independent monitors for interconnection studies.

The final set of reforms would speed transmission construction, starting with improved reporting on transmission construction progress, and also industry and government collaboration to reduce supply chain bottlenecks.

 The 129-page report is titled “Unlocking America’s Energy: How to Efficiently Connect New Generation to the Grid.”

From pv magazine Global

Researchers funded by the US Navy have developed a novel coating for underwater solar cells that prevents biofouling while preserving visible light transmission. Biofouling, the attachment and growth of organisms, can reduce the optical efficiency of solar cells. These cells are used in unmanned and autonomous underwater vehicles for naval surveillance, oceanographic research, and other applications.

“The necessity of the present study is highlighted by the current lack of coating systems that are both fouling-resistant and maintain light transmittance on their own,” said the academics. “Existing coatings require regular human intervention, such as mechanical cleaning and grooming techniques, to maintain efficiency, which is a tedious and labor-intensive process. The proposed self-polishing technology has the potential to eliminate the need for mechanical grooming, offering a more efficient and less labor intensive solution.”

The novel solution uses ultra-low concentrations of nano-sized, seawater-soluble pigments, such as cuprous oxide (Cu2O) and zinc oxide (ZnO), combined with an organic biocide and a fast-polishing binder. The team explained that when these coatings are exposed to seawater, the pigment particles dissolve, creating a porous layer that allows seawater to diffuse into the coating.

“This leached layer enables the dissolved biocidal compounds to diffuse out of the coating and into seawater,” they said. “The leached layer binder matrix reacts with seawater ions and forms soluble compounds in a controlled manner. To balance this and establish a higher or lower polishing rate, self-polishing coatings use copolymers that may or may not hydrolyze in seawater. As the hydrolysis continues, the eroding polymer and dissolving pigment fronts expose fresh layers of acrylate polymer and pigments, leading to a self-polishing effect with a more or less stable leached layer thickness.”

The research team tested different binder systems for the coating, using various particle mixtures. They used silyl acrylate (SA) alone or combined with rosin (SA-R) in a 70:30 weight ratio for the binders. The particle mixtures included nano-sized cuprous oxide (NC), nano-sized zinc oxide (NZ), the organic liquid biocide SeaNine 211 (SN), micron-sized cuprous oxide (MC), and micron-sized zinc oxide (MZ).

They applied the coatings to 6 mm thick, smooth, transparent polycarbonate substrates measuring 200 mm × 100 mm. The coated panels were submerged in Hundested Harbor, Denmark, for two and a half months, with inspections and photographs taken after two, six, and 10 weeks.

“The combined action of NC, NZ, and SN in an SA-R coating provided a significant fouling resistance throughout the 12-week exposure period, attributed to the synergistic rate of dissolution effects and the rapid polishing rate of the SA-R binder,” the researchers said.

This champion coating had an NC pigment volume concentration (PVC) rate of 0.04%, NZ PVC of 0.08%, and weight percent of solvent-free coating basis (SN) of 3%.

“The same formulation exhibited a complete polish through by week 12, after which the coating started to foul, implying a high polishing rate of about 1.4 μm/day, surpassing conventional rates of 5–15 μm/month (0.15–0.5 μm/day),” the researchers said. “Further testing with the formulation was conducted by the Office of Naval Research (ONR) in Florida, where the coating showcased exceptional resistance to biofouling in warm (22 C to 30 C) seawater with extreme fouling conditions. Solar power generation remained close to 100% efficiency throughout a 13-week.”

he researchers said the nano-sized versions of Cu2O and ZnO are about 20 times more expensive than the conventional micron-sized versions. However, they noted that the low volume required in the developed solution keeps formulation costs relatively low.

The Technical University of Denmark researchers described their work in “Self-sustaining antifouling coating for underwater solar cells,” which was recently published in Progress in Organic Coatings.

Researchers from Italy’s University of Camerino have developed a novel way to recover silver from end-of-life solar cells.

Combining hydrometallurgical and electrochemical processes, they were reportedly able to recover pure silver at an efficiency of 98%. Hydrometallurgical processes, or leaching, use aqueous solutions to extract metals, while electrochemical processes refer to the use of electric currents to drive reactions in metals.

“The retrieval of raw materials is crucial for multiple reasons,” explained the academics. “Conventional metal extraction techniques, such as open-pit mining, can inflict substantial harm on the environment and neighboring ecosystems. Therefore, employing a metal recovery process based on industrial wastes can mitigate the environmental impact associated with metal production. Additionally, metal recovery generally requires less energy than extracting metals from ore, leading to reduced energy consumption and lower carbon emissions, especially if the recovery rate is comparable to or higher than traditional extraction methods.”

Due to the close values of the standard reduction potential of silver and copper, the leaching of silver particles from PV waste is challenging. To overcome this, the researchers proposed a combined base-activated persulfate and ammonia, with persulfate acting as an oxidizing agent, while the system itself generates a protective hermetic layer of copper (II) oxide, preventing its own leaching.

To test the proposed process, the researchers conducted an experiment consisting of varying parameters for the leaching process. Those were the concentration of ammonia (NH₃) in a solution, measured in moles per liter (mol/L); PV waste sample, in grams per liter (g/L); potassium persulfate (PPS), in mol/L; and reaction time, in minutes. The temperature was kept at 25 C and the stirring rate at 300 rpm during all the experiments.

“The following conditions were chosen as best: 0.5 M of NH₃, 0.2 mol/L of PPS, S/L ratio to 50 g/L, and reaction time set to 60 min,” the academics explained. “Two additional experiments were conducted under these conditions to assess reproducibility. When combined with the two previous tests from the experimental design, an average of 85.0±2.6% was achieved at a 95% confidence interval.”

Despite these good results, 85% of the recovered pure silver was considered insufficient by the research group, which decided to initiate the electrochemical process. Namely, the electrodeposition-redox replacement (EDRR) approach using a pulsed electrodeposition method. “This technique, previously reported in the literature, enables the recovery of highly pure silver metal from hydrometallurgical leachate containing copper ions,” the team explained.

The best conditions for silver recovery were found to be with the EDRR approach, which reportedly achieved an efficiency of 98.7%. “It is noteworthy to mention that this approach proves to be selective in its recovery of silver and does not require any chemical addition. This unique feature renders this methodology competitive in comparison to conventional processes,” the scientists concluded.

The novel method and the results of the experiments were presented in “Silver recovery from silicon solar cells waste by hydrometallurgical and electrochemical technique,” published in Environmental Technology & Innovation. The study was conducted in partnership with ORIM, an Italian company specializing in metal recovery from solid waste.

From pv magazine Global

University of California San Diego researchers have developed an automated material discovery and testing platform for tandem perovskite solar cell technologies. The robotic platform is multifunctional, able to mix precursors, perform spin coating, annealing and characterization of the optoelectronic thin films.

Focused initially on perovskite technology, it is called Perovskite Automated Spin Coat Assembly Line (PASCAL). It is suitable for composition engineering to improve the durability of perovskite absorbers for tandem solar cell applications, and screening triple-cation, triple-halide compositions.

“In our view, having a robot perform repetitive tasks is resource efficient, freeing up well-trained researchers for the higher-level tasks of hypothesis generation and testing,” David P. Fenning, corresponding author of the research, told pv magazine. “It also reduces noise in experimental data, increasing statistical power in experiments.”

The novel platform reportedly enables a rate of up to 430 sample depositions or measurements per day. “PASCAL automates fabrication of thin films by the standard spin coat procedures employed in manual processes, albeit with precision, control, and record keeping surpassing that of human operators,” stated the researchers.

PASCAL enables extensive compositional screening and a capacity to analyze 58 “unique compositions” within the complex realm of triple-halide, triple-cation compositions. It also supports coating reproducibility as demonstrated in the work by the team.

“With this screening dataset, we leverage machine learning to develop a durable composition that displays nearly zero photoluminescence peak shifts under both 85 C and approximately 4-sun photo exposure,” said the academics.

The composition was then made into single-junction prototype devices. In the characterization line are cameras, LED, and laser excitation sources, a halogen lamp, and a spectrometer. It can generate a standard dataset of darkfield, brightfield, photoluminescence, and transmittance data, stored for each sample.

The complete system is controlled from a single computer using a customized Python library.

Looking at the results, the research asserted the efficacy of PASCAL specifically for automation of solution-processed optoelectronic thin film research.  The approach, the hardware, and data are “evidence that automated platforms are an opportunity to accelerate the identification and discovery of novel thin film materials.” The accessibility of low-cost robotics and open-source communities for automation was an enabler, noted Fenning.

The platform was presented in the study “PASCAL: the perovskite automated spin coat assembly line accelerates composition screening in triple-halide perovskite alloys,” published in Digital Discovery.

Feedback from industry and the research community has been positive. “We have heard a lot of encouragement and excitement from early career to very senior researchers both in industry and academia. I think our most significant input to them might be that it’s not as hard or expensive as it might have once been, given the advances in robotics and open-source platforms available,” said Fenning,

Looking ahead, Fenning said, “Operational stability is the name of the game for perovskites. We are working on studies connecting durability to chemical and process variations using the low-noise experimental foundation provided by PASCAL.”

He added that the PASCAL platform is supporting research for “scale up of perovskite processing” at a new research center led by the Massachusetts Institute of Technology (MIT), which received funding from the U.S. Department of Energy Solar Energy Technologies Office (SETO). It is called Accelerated Co-Design of Durable, Reproducible, and Efficient Perovskite Tandems, dubbed ADDEPT, a national center that includes university research teams from the University of California San Diego, Princeton, and MIT, as well as industrial partners, CubicPV and Verde Technologies.

From pv magazine Global

Scientists from Canada’s Western University have designed a novel open-source autonomous virtual utility to monitor PV users and enable P2P trading. Their SolarXchange blockchain technology-based system creates smart contracts by itself, facilitating transactions between users on an hourly basis. “We are really interested in working with forward-focused electric utilities that want to enable widespread distributed solar generation and P2P exchanges to make a truly resilient electric grid,” corresponding author Dr. Joshua M. Pearce told pv magazine. 

“For utilities that choose to embrace distributed generation there are various business models. One tantalizing approach is to enable P2P trading of solar electricity,” the academics said. “The primary issue is that billing systems have been set up for centralized power production, a new method of billing/ trading is needed that is made for distributed generation. One approach is to use blockchain technology because it allows secure transactions.”

The novel virtual utility is based on two levels of contracts, written using Solidity, one of the popular smart contract languages. In the blockchain context, smart contracts are codes that automatically carry out tasks when certain conditions are met. On the first level, each participating house has a House contract, describing the general state of the user’s PV generation and demand. On the second level, the virtual utility runs the HouseFactory contract, which absorbs information from the first-level contracts, keeping track of the individual homes’ demand and production and deciding when electricity should be exchanged.

“Unit tests for each of the contracts’ methods are written in Solidity, and data on gas usage and costs is collected. It should be noted that the ‘gas’ in the context P2P networks refers to the unit of measurement for transaction fees and computational costs not natural gas,” the group said. “The total cost of deploying the contracts were calculated by migrating the contracts onto the local Truffle blockchain and retrieving the gas usage and cost information from the terminal output.”

Following the testing of the blockchain functions, a JavaScript simulation is developed to use the contracts on actual load and PV generation data for one year on an hourly basis. The simulation considers two scenarios: both include 10 homes and real electricity information from New York City. The first case study, “True Peers,” represents a mature system in the future where all the houses are prosumers with PV of their own.

“The second case study is called the Intermittent Transition. In this case study there are four types of houses,” the scientists explained. “First, one-quarter of the houses have twice the PV they need for self-consumption, representing households with large unshaded rooftop areas. Second, one-quarter have enough PV to match their electric load annually, which would represent the way most rooftop PV systems are designed today to take advantage of net metering rates. Third, one-quarter of the houses have only half the PV necessary to match their load, which would represent houses on a small lot or in a non-optimal. Finally, one-quarter have no PV representing households without available PV surface space because of shading or households without access to capital to install PV.”

The True Peers case study led to 521 kWh of energy exchanges, yielding total annual cost savings of $70.78 under a time of use (ToU) rate structure. In contrast, the Intermittent Transition case study resulted in 11,478 kWh of exchanges, with total net savings of $1,599.24 under the same ToU rate structure.

“Having a greater variability in PV production thus resulted in increases of more than a factor twenty in exchanges and net cost savings,” said the researchers.

“This research aims to show that it is possible to create a gas effective P2P virtual net metering system that is minimal maintenance for users while still saving users money,” the group concluded. “As a result, this system makes owning PV and participating in a P2P network more accessible. Both PV owners and non-PV owners benefit from participating in this system, as seen from the Intermittent Transition case study. Utilities should adopt the role of the virtual utility in the proposed system to centralize the P2P process.”

They presented their system in “Using a ledger to facilitate autonomous peer-to-peer virtual net metering of solar photovoltaic distributed generation,” which was recently published in Solar Energy Advances.

From pv magazine Global

Researchers led by scientists from Mohammed First University in Morocco explored the use of solar panels equipped with an anti-reflective coating at Green Energy Park, a Benguerir-based test facility located at a site that has favorable solar irradiance reaching 2,239 kWh/m2/year but a harsh climate, with high temperatures, low precipitation, and high level of aerosols.

The experiment involved setting up two commercial modules side-by-side, one with an anti-reflective (AR) coating and the other without.

“It is the first study to comprehensively assess the electrical, optical, durability, and economic aspects of AR coatings simultaneously and under real, harsh outdoor conditions,” Ahmed Alami Merrouni, corresponding author of the research, told pv magazine, adding that the “unexpected yet significant result” was the “considerable reduction” of 2.7% for the levelized cost of energy (LCOE).

The scientists assessed the electrical performance of the AR-coated PV modules over a 10-month period, carrying out frequent cleaning, and weekly transmittance measurements. Using the results from the field study, the team calculated the effect AR-coated modules would have on financial performance in a large-scale PV plant, using a 40 MW PV power plant as a case study.

“The simulation results unveil that a 40 MW power plant employing standard PV panels yields an annual electricity output of 69 GWh. In contrast, an analogous power plant incorporating ARC-coated panels attains an elevated electricity generation of 72 GWh, signifying a notable 5.5 % enhancement in comparison to conventional panels,” stated the researchers.

“From an economic standpoint, the simulation outcomes reveal an LCOE of 0.037€/kWh for the 40 MWe power plant utilizing non-coated PV modules. Conversely, the LCOE for the same power plant employing ARC modules amounts to 0.0368 €/kWh, showcasing a 2.7 % decrease in electricity production costs,” they added.

Laboratory abrasion tests on AR-coated glass samples were also conducted to determine the impact on optical performance and coating durability.

“Our study found that after 1,500 abrasion cycles, which simulate 29 years of weekly cleaning, the optical properties only decreased by 2.6%. This impressive durability opens the possibility of using dry cleaning methods for PV power plants with this coating, significantly reducing cleaning costs and conserving water,” said Alami Merrouni.

The AR-coated glass samples also demonstrated “good optical performance against soiling”, with soiling losses lower by 3.7 % compared to non-coated samples for the same exposure period, according to the scientists.

Since carrying out the study, feedback from other researchers in the field of solar energy and Moroccan governmental organizations has been positive, according to Alami Merrouni.  “The most highlighted and significant result that attracts attention is the durability of the AR coatings under linear abrasion tests,” he said.

“This feedback underscores the practical benefits and potential for the wide adoption of AR coating solutions, especially in regions like Morocco where, in addition to its high performances, the AR coating may open the possibility of using dry cleaning methods enabling a significant reduction on the cleaning costs and water saving, which is crucial for desert locations,” he concluded.

The research is detailed in the paper “Experimental analysis of Anti-Reflective coating performance in desert Climate: Yield analysis, soiling impact and cleaning durability evaluation,” published in Sustainable energy technologies and assessments.

Scientists from Colorado State University have conducted field research on vegetable crop growth located below PV modules with varying transparency. The vegetables are grown under thin film, semi-transparent cadmium telluride (St-CdTe) modules with a transparency of 40%, bifacial monocrystalline silicon (BF-Si) modules with a transparency of 5%, and opaque polycrystalline silicon (O-Si) modules with a transparency of 0%.

“Semi-transparent PV (STPV) module technology has emerged as a potential solution to mitigate the negative effects of dense shade in cropping systems while maintaining a high module density,” said the academics. “To our knowledge, this is the first replicated research experiment that evaluates module transparency types in an irrigated vegetable field setting.”

The experiment was conducted over two growing seasons, 2020 and 2021. The study site was located in Fort Collins, Colorado, USA, in a field designated for research. Overall, the growth of six vegetables was tested: jalapeño pepper, bell pepper, lettuce, summer squash, Tasmanian chocolate tomatoes, and red racer tomatoes.

“There were three planted rows across the entire site – north, middle, and south,” explained the group. “Lettuce, peppers, and tomatoes were planted in two offset sub-rows in 0.9 m beds covered with black plastic mulch in the north and south rows. Squash was exclusively planted in the middle row both years with 1.2 m spacing on center.”

As for the PV modules, the scientists used three of each type. They were installed in a set position of 35 degrees facing south, with the bottom edge of the modules 1,220 mm above the ground and the back at a height of 2,360 mm. The ST-CdTe modules had a rated output of 57 W, the BF-Si had 360 W, and the O-Si had 325 W.

“Each of the 12 crop subplots, including both PV arrays and control plots, spanned a width of 4.3 m, with a 4.3 m spacing between adjacent subplots,” the researchers said. “Due to the single pole mount configuration, the shadow cast from the modules moved throughout the day. With this, the crops received direct sun early and late in the day, with maximum shade during the peak hours of the day and immediately under the modules.”

Per the results, the summer squash under all three module types displayed significantly lower yields than the control plot, regardless of the module transparency type. While in the control plot, under full sun conditions, the squash yielded 5.1 kg per plant, it grew 3.2 kg in the BF-Si scenario, 3.2 kg in the O-Si scenario, and 4.1 kg in the ST- CdTe scenario.

The other vegetables had equal or higher average yields to the control under the 40% transparent ST-CdTe treatment but with no statistically significant differences. The jalapeño peppers yielded 155 g per plant in full sun, 161 g in the BF-Si, 155 g in the O-Si, and 162 g in the ST- CdTe, while the bell pepper yielded 295 g per plant in full sun, 294 g in the BF-Si, 278 g in the O-Si, and 346 g in the ST- CdTe.

The lettuce weight per head was 105 g in full sun, 126 g in the BF-Si, 111 g in the O-Si, and 129 g in the ST- CdTe. The Tasmanian chocolate tomatoes had an average of 926 g per plant in full sun, 1,060 g in the BFSi, 1,069 g in the O-Si, and 1,278 g in the ST- CdTe. Lastly, the red racer tomatoes had 867 g per plant in full sun, 733 g in the BF-Si, 903 g in the O-Si, and 962 g in the ST- CdTe.

“The optimization of the agri-PV array with semi-transparent PV modules could increase agricultural production while maintaining the added protection of an energized canopy in traditional APV systems,” the researchers concluded. “More research is needed to better understand the economic tradeoffs between increased module transparency compared to vegetable crop production, while also considering the increased energy yield from module bifaciality.”

Their findings were presented in “Vegetable Crop Growth Under Photovoltaic (PV) Modules of Varying Transparencies,” published in Heliyon.

People on the move: Mayfield Renewables, First Solar, Meteomatics Job moves in solar, storage, cleantech, utilities and energy transition finance.

Net metering hangs in the balance in New Hampshire A group of interested parties, including the state’s utilities and the Granite State Hydropower Association, agreed on a settlement that calls for the rate to stay the same for two years.

Northvolt closes Cuberg’s ops, shifts lithium-metal battery R&D to Sweden Three years after acquiring U.S.-based Cuberg, Swedish battery maker Northvolt has decided to shut down the California unit and move future lithium-metal battery R&D to Sweden.

PV module cooling tech based on single-channel containing nanofluids Scientists in Mexico have conceived a new solar module cooling tech that can reportedly improve PV power generation by up to 2%. The system uses nanofluids embedded in an aluminum single-channel attached to the back of the panel.

GM signs agreement to match assembly plant power demand with solar The automaker entered a 15-year, 180 MW solar power purchase agreement (PPA).

From pv magazine Global

Researchers from India have proposed a novel bifacial electron transport layer (ETL)-free cell structure for flexible devices. They optimized this cell using SCAPS-1D simulation software, selecting the most effective combination of front transparent electrode (FTE), hole transport layer (HTL), and rear transparent electrode (RTE). The new structure has achieved a power conversion efficiency (PCE) surpassing 27%.

“ETL-free perovskite solar cells (PSCs) are the most promising and acceptable devices for developing flexible PSCs due to lower temperature processing, the simplest configuration, and the elimination of complex preparation routes, which reduces energy and time,” said the researchers. “They can be easily processed by roll-to-roll method, spray coating, inkjet printing, and can be encapsulated with low-cost flexible layers.”

The scientists began with a reference structure consisting of an FTE layer of PFTO; interfacial defect layer (IDL)1; a perovskite layer (FA0.75MA0.25PbI2.5Br0.5); IDL2; HTL layer of Spiro-OMeTAD; IDL3; and an RTE layer of Cu/Cu2O (PFTO/IDL1/FA0.75MA0.25PbI2.5Br0.5/IDL2/Spiro-OMeTAD/IDL3/Cu/Cu2O). They set the perovskite layer thickness to 600 nm.

“Upon selecting a suitable FTE, we observed that the lower value of conduction band offset (CBO) at the FTE/perovskite interface exhibits improved device performance due to the potential-well-like structure,” the group explained. “CuI and CuSCN show superior band alignment with the perovskite absorber layer compared to other HTLs, resulting in improved device performance. The electron affinity of RTE plays a crucial role in the band alignment at the RTE/HTL interface and, hence, the device performance.”

After finalizing the champion cell, the group investigated its bandgap and thickness.

“The device PCE increases up to an optimized bandgap of 1.4 eV, achieving a PCE of 24.65% (front illumination) and 25.48% (rear illumination). Beyond this bandgap, the PCE starts decreasing,” the results showed. “After optimizing the thickness of the absorber layer (800 nm) with a defect density of 1.0 × 10^14 cm−3, the PCE improves to 26.88% and 27.35%.”

They presented their results in “Performance optimization of ETL-free bifacial perovskite solar cells for flexible devices: A simulation study,” which was recently published in Next Energy. The team included researchers from India’s National Institute of Technology and the Indian Institute of Technology.

From pv magazine Global

Researchers from Mexico’s University of Sonora (UNISON) and the National Technological Institute of Mexico have conducted a numerical study of the thermal performance of a single-channel cooling system for photovoltaic modules.

In their simulation, they used different kinds of nanofluids, such as aluminum oxide (Al₂O₃), copper(II) oxide (CuO), and zinc oxide (ZnO). In addition, they have equipped the system with baffles, which are structures placed inside a cooling channel to improve heat removal.

“The system includes nine equally spaced baffles, which act as deflectors. The baffles are inclined to 45 degrees with a height of 1 cm. They favor the contact of the cooling fluids with the back of the panel, increasing the effective heat transfer coefficient,” explained the group.

The model included the five layers that make up a 13%-efficient photovoltaic panel – glass, ethylene vinyl acetate (EVA), solar cell, tedlar, and thermal paste, as well as the proposed aluminum channel with a height of 3 cm through which the cooling fluid circulates. “This cooling fluid can be either a nanofluid or pure water,” the scientists explained.

The numerical model was constructed using the software Ansys Fluent v20, based on the finite volume method. The PV system model and the flow of nanofluids under the laminar flow regime were validated against previous literature results, showing a “reliable basis for modeling PV systems and their interaction with nanofluids.”

In all cases, the metal oxides were suspended in water, with changing volumetric concentrations of 0, 0.01, 0.05, and 0.1, respectively. They used a range of reynolds numbers (Re), which are the measure used to determine whether fluid flow is smooth or chaotic, ranging from 18 to 42. A fluid inlet temperature of 34 C was assumed.

The scientists found that the nanofluid composed of CuO was the most effective, improving efficiency by 5.67% compared to pure water in the lowest Re range. “The concentration of 0.1 vol in the nanofluid produces a more effective reduction in the temperature of the photovoltaic cell, which reaches up to 15 % when the Reynolds number increases from 18 to 42. The increase in Re from 18 to 42 boosted electrical efficiency by 4%,” they further explained.

In addition, the group also found that electric efficiency improved by 1.40% by increasing the nanofluid concentration from 0 to 0.1 and that increasing the radiation from 200 W/m2 to 1,000 W/m2 decreased the efficiency by 6.5% for pure water and 5.5% for the nanofluid. “Baffles improve heat transfer in specific channel areas, resulting in a 2% increase in electrical efficiency due to fluid flow redirection and acceleration,” they concluded.

The cooling system was presented in “Numerical study of the thermal performance of a single-channel cooling PV system using baffles and different nanofluids,” published in Heliyon.

From pv magazine Global

A new IEA-PVPS report says that PV systems need to take on additional grid support tasks traditionally managed by conventional power plants to ensure the stable operation of electrical power systems throughout the world. The Task 14 report ties up IEA-PVPS’ work on the potential of distributed solar and PV hybrid systems to provide frequency-related grid services.

It says that existing PV systems already have the technical capabilities to provide various frequency-related grid services, such as the reduction of active power generation in cases of overfrequency and, when in combination with battery energy storage systems (BESS), the automatic increase of their output in case of underfrequency.

The report predicts that the provision of such fast-frequency services by PV systems, with or without batteries, will become “very important in the near future,” particularly in supply areas which are dominated by inverter coupled generators.

It also features five case studies – two in Japan and one each in Austria, Germany and Italy – that cover the regulations, grid codes and frameworks that influence the operation of power systems in the region.

The report says each case study “clearly demonstrated that PV systems solely, or especially in combination with BESS, are able to provide different types of frequency-related grid services.” It adds that while the results of the case studies are promising, “further research and demonstration projects are necessary, especially for implementation of these frequency related services, which come along with grid-forming inverters.”

Gunter Arnold, one of the authors of the report, says that the study represents a major step forward in recognizing and using PV systems for frequency-related grid services. He says that the report’s insights will be crucial for policymakers, grid operators, and the renewable energy sector as the world moves toward a more sustainable energy future.

IEA-PVPS also recently wrapped up its 13th task, with the publication of a report on the optimization of bifacial PV tracking systems.

From pv magazine Global

Student solar car teams from Canada’s Polytechnique Montréal and École de technologie supérieure made it to the podium at the Electrek American Solar Challenge 2024, a distance-based competition for solar cars.

With a multiple occupant vehicle (MOV) named Esteban 11, students from Polytechnique Montréal won first place in the MOV category in both the qualifier circuit race, known as the Electrek Formula Sun Grand Prix (FSGP) and in the main race, the Electrek American Solar Challenge, which requires completing a minimum of 1,500 miles (2,400 km).

The Esteban team completed 1,610.3 miles at an average speed of 36.2 mph (58.26 km/h), with an overall score of 73.86. The MOV category is scored on factors beyond the distance covered, such as practicality, amount of external energy used, and whether the 35 mph target average speed was maintained.

The other Montreal team, hailing from École de technologie supérieure, won silver in the single occupant vehicle (SOV) category, completing 2,004.5 miles with the Éclipse XI solar car. The SOV class is scored solely on miles driven. Only in the event of a tie is elapsed time relevant.

This year’s winner of the SOV class was the University of Michigan student team with its Astrum solar car, completing 2,095.5 miles (3,372 km) with an average speed of 37.51 mph.

Esteban 11 by the Polytechnique Montréal student team

The Esteban project spokesperson told pv magazine that the team began competing with a two-seater MOV in 2019. “Switching categories allowed us for more creativity in our design. Being multiple occupants also displays the efficiency of our car. Especially in the event, the broader public gets to learn how the technology evolves,” said the Esteban spokesperson.

The team used a 1218 W solar array with cells from Singapore-based Maxeon and encapsulation by German specialist PV panel manufacturer OPES Solutions. The 4-wheel vehicle weighed 293 kg, measuring 4.92m x 1.8m x 1.04 m. The battery was a 9.2 kWh by China-based BAK Technologies, weighing 47 kg, paired with two 5kW M2096D-3 hub motors from Japan’s Mitsuba in a carbon fiber monocoque.

“One great challenge we had was splitting the battery pack. This allowed us to have a lower center of gravity but complicated the monitoring and protection,” the spokesperson said, adding that a new printed circuit board design adhering to professional standards with features to manage heat effects also made a difference this year.

Éclipse XI by the École de technologie supérieure student team

The Éclipse XI, a 3-wheel design weighing 200 kg, measured 4.5 m x 1.5 m x 1.1 m. It was equipped with a 1000 W solar array spanning 4m2, based on Sunpower Maxeon Gen 3 solar cells. It had a 20 kg 5kWh lithium ion battery by Japanese manufacturer Panasonic.

The Éclipse XI team not only won a silver medal in the American Solar Challenge competition, it also won two awards, an Electrical Design Award, and the Abe Poot Award. The latter is named after an influential figure in the U.S. solar car racing community, that recognizes team spirit of collaboration and cooperation, according to the Éclipse XI team spokesperson.

The Electrical Design Award recognized the performance of the electrical setup. “At FSGP, we were the first team to complete both electrical and battery protection system inspection with all green status. We also proved that our electrical systems were robust and reliable along both races, more than 4500 km without any issue,” the Éclipse team spokesperson told pv magazine.

“For this race, we used a custom-made motor casing with air cooling system to help us climb the most steeped hills along the route,” they said, adding that the team is currently working on an improved maximum power point tracking that will “maximize efficiency across all operating ranges” to be able to reduce overall weight and cost.

The Electrek American Solar Challenge 2024 attracted over 30 student-run teams from the U.S. and Canada. It began on 20 July in Nashville, Tennessee, and ended in Casper, Wyoming, on 27 July. The primary route has 1562.2 total miles to complete and vehicles must average at least 35 mph for the event. There are seven optional loops to earn additional points.

Researchers at the U.S. Department of Energy’s National Renewable Energy Laboratory (NREL) used a circular economy framework to determine how to scale, deploy, and design future metal halide perovskite solar panels to be easily recyclable.

As initiatives to commercialize metal halide perovskite (MHP) solar technology are underway, especially efforts to ensure durable performance in the field, NREL researchers initiated a study of sustainability design factors as another important aspect of commercialization.

“Our goal with this perspective paper was to point out that existing technology does not prioritize building products with sustainability and circularity up front. It was not developed specifically to minimize waste or use the lowest energy processing steps,” Joey Luther, the research’s corresponding author, told pv magazine. “However, since PV is inherently a sustainable technology, now is the time to begin to evaluate how we can develop the commercialization of MHPs with sustainability in mind.”

The group performed the evaluation based on a a prototypical single-junction MHP module close to commercial designs, framed with mounting rails in a glass-glass module configuration with polymer encapsulants, and edge sealing typical of silicon and cadmium telluride panels. The individual PV cells are integrated via scribing, and include front glass coated with a transparent conductor, the MHP layer sandwiched between electron and hole transport materials and a back electrode.

In addition, the team drilled down into constituent chemicals, molecules, and materials typically used in perovskite A, B, and X sites.

For all of the above, sustainability aspects were evaluated, such as energy intensity of manufacturing, carbon intensity, rare mineral mining, recyclability, earth abundance, cost, fossil fuel derived, fail-safe encapsulation, health hazards, and flammability among others.

The prototype was further evaluated based on critical material concerns, embodied energy, carbon impacts and circular supply chain processes. The analysis included the frame, rail materials, front and back glass, encapsulation polymers, solvents, electron and hole transport materials, and electrode materials.

In an information-rich table, the team detailed how the eleven “Rs” of circularity for photovoltaics can offer opportunities and advantages within sustainable manufacturing. An adaptation of the “reduce, reuse, recycle” concept, some of the Rs discussed are listed here: refuse fossil fuels and carbon-intensive materials; reduce energy, material, and carbon input, repair or design for repair, reuse, repower, restore, and recover energy.

When it comes to recycling, the researchers noted that ‘recycling’ includes both downcycling to lower-value, or lower-quality, products. They explained that recycling is beneficial when recovered feedstocks replace virgin materials, which require energy-intensive refining. There is room for improvement. For example, PV glass manufacturing is still using virgin sources in new PV glass products and not post-consumer PV glass cullet, they noted.

The team identified five key areas and opportunities to pursue. The first is enhancing MHP module reliability to meet current commercial PV lifetime standards. Second, investigate the supply chain of low-trade-volume raw materials, such as cesium, and ensure adequate accessibility for the sustainable scale-up of a given MHP composition, or focus research, to reduce or substitute. Third, seek alternatives to indium. Fourth, explore how to accelerate PV glass recycling without downcycling. And fifth, further improve module remanufacturing processes.

“A reasonable combination of these solutions would enable MHP-PVs to contribute meaningfully and sustainably to the energy transition,” stressed the team.

The scientists asserted that “circularizing the PV supply chain, particularly through recycling and remanufacturing glass”, provides opportunities to lower the embodied energy and carbon of MHP-PVs. “Improvements in lifetime and reliability remain paramount for the energy transition and provide the largest benefits,” they concluded.

The perspective is detailed in “Sustainability pathways for perovskite photovoltaics,” published by nature materials.

From ESS-news.com

The U.S. Department of Energy (DOE) announced the opening of the Grid Storage Launchpad (GSL), a new facility at the Pacific Northwest National Laboratory (PNNL) in Richland, Washington.

The 93,000-square-foot or nearly hectare-sized research facility will house 30 laboratories and about 100 researchers. It is equipped to evaluate new battery materials and battery systems up to 100 kW operating under realistic grid conditions.

The DOE hopes that the ability to collaborate with scientists, engineers, industry, and agencies in one building will accelerate the development and roll-out of new grid-scale storage energy technologies and ideas.

Along with research initiatives, GSL will serve as an educational center, training technicians, grid operators, first responders, safety officials, and more.

Vince Sprenkle, energy storage expert and GSL’s first director said: “Energy storage will be a significant part of a resilient and reliable grid that’s fully decarbonized. And GSL will help us get there,” said “GSL is truly an integrated facility that incorporates everything from fundamental materials research to testing 100-kilowatt batteries.”

Read the rest of the article on ESS-news.com.

From pv magazine Global

A research team has determined that covering the world’s highways with solar roofs could generate 17,578 TWh per year, which is more than 60% of global electricity consumption in 2023.

Their study, titled “Roofing Highways With Solar Panels Substantially Reduces Carbon Emissions and Traffic Losses,” was recently published in the journal Earth’s Future. It explores the potential to install solar panels above highways and major roads.

With more than 3.2 million km of highways worldwide, the researchers calculated the costs and benefits of constructing a solar panel network using polycrystalline solar panels with a 250 W capacity. The analysis found that covering highways with solar panels could generate more than four times the annual energy output of the United States and offset 28.78% of current CO2 emissions, while also reducing global traffic deaths by 10.8%.

“This really surprised me,” said Ling Yao, a remote sensing scientist at the Chinese Academy of Sciences and the study’s lead author. “I didn’t realize that highways alone could support the deployment of such large photovoltaic installations, generating more than half of the world’s electricity demand, and greatly easing the pressure to reduce global carbon emissions.”

The researchers also identified regions such as eastern China, Western Europe, and the US East Coast as the most ideal for deployment, despite challenges related to setup and maintenance costs. Yao noted the importance of pilot programs to demonstrate the practicality of this concept.

The research team consisted of academics from the Chinese Academy of Sciences, Tsinghua University and Chinese Academy of Geosciences, all located in Beijing, as well as New York’s Columbia University.

From pv magazine Global

A research group led by scientists from Purdue University has created a novel model for assessing the growth of corn in agrivoltaic facilities and has proposed to use a spatiotemporal shadow distribution (SSD) model to optimize crop yield and power production.

The new method is based on the agricultural production systems simulator (APSIM) plant model, which is based on finer temporal resolution, with literature reportedly supporting its validity. The SSD model, which accounts for the shadow cast by the PV panels, was used in conjunction with the National Renewable Energy Laboratory (NREL) radiation data. These combined data were then calibrated and validated with the results from their field measurements.

The field experiment was conducted at an agrivoltaic farm at Purdue University in West Lafayette, Indiana, USA. There, PV panels were deployed in two arrangements, either 300 W modules placed adjacent to each other or 100 W modules arranged in an alternate checkerboard pattern. They all used single-axis trackers and are 6.1 meters high. The set-up was tested between April and October of 2020.

“For validation, 12 plots are considered,” the academics said. “Corn ears of three representative plants from each of these plots were hand-collected. Overall, 570 corn plants from the without-PV region and 36 corn plants from the with-PV region, respectively, were used in the analysis. The ears were cleaned, imaged, and processed using a DuPont pioneer ear photometer.”

The field measurement showed that the corn yield from the area without PV was measured to be 10,955 kg/ha, compared with the yield of 10,182 kg/ha of the PV area. That was in reported agreement with the novel model, which predicted 10,856 kg/ha for the no-PV area and 10,102 kg/ha for the agri-PV field.

The researchers then used the model to test the impact of the tracker height, distance between arrays, panel angle, and the activation of the tracking system on yield. They first found that designs that lower the tracker height without impeding the movement of plant machinery should be envisioned as the overall average corn yield is a weak function of the tracker height up to 2.44 m.

“However, the variability from one corn row to another increases as the tracker height is reduced,” they further explained. “Another interesting finding is that for our PV module sizes, increasing the distance between the adjacent PV rows beyond 9.1 m, while keeping the total power over the entire land constant, does not lead to an increase in corn yield based on the total land area.”

They also found that anti-tracking (AT) around solar noon provided the most significant increase in the corn yield. “However, this increase in corn yield of 5.6% is quite modest and should be weighed against a substantial decline in solar power,” the group emphasized.

The proposed model was presented in “Optimizing corn agrivoltaic farming through farm-scale experimentation and modeling,” published in Cell Reports Sustainability. The research group also included academics from Denmark’s Aarhus University.

From pv magazine Global

An Indian-Chinese research team has developed a novel dual-axis solar tracking system based on sensors and a controller module.

“In this work, an attempt was made to design and implement a single tracking motor with dual axis for a simple yet effective control system,” the researchers said. “No programming or computer interface is required as standard electronic circuits are used. This system is independent and self-sufficient.”

The group explained that the novel system uses two different sensor types – an ultraviolet (UV) sensor and a micro-electromechanical solar (MEMS) sensor. “The UV sensor calculates the intensity of UV radiation received from the sun, and the MEMS sensor forecasts the sun’s path across the sky,” they added.

The data collected by those sensors are then fed into an arithmetic optimization-based PID (AOPID) controller, which uses arithmetic-based functions to attain a better response time, tracking accuracy, and disturbance rejection.

“The AOPID controller utilizes the inputs from the UV and MEMS sensors to modify the position of the solar panels and optimize energy capture,” the scientists further explained. “The controller achieves this by using a feedback loop that adjusts the controller’s proportional, integral and derivative gains to reduce the variation between the set-point and the real location of the solar panels through the use of arithmetic optimization algorithms.”

The academics tested the proposed system using MATLAB simulation software based on a 50 W simulated PV panel. They then compared its power production and consumption over a few hours to those of a simulated fixed-tilt PV system.

“The comparative energy analysis graph demonstrates that the dual-axis solar tracking system that was suggested was more productive than the fixed-tilt solar tracking system and matrix converter,” the researchers “Achieving a high net energy requires precisely adjusting the controller’s parameters and positioning the panels.”

The system was presented in the paper “Solar PV tracking system using arithmetic optimization with dual axis and sensor,” published in Measurement: Sensors. The research was conducted by scientists from China’s Xinxiang Vocational and Technical College and India’s Publon Research Centre.

From ESS news

ION Storage Systems has reached the 800-cycle mark with its solid-state battery, which it plans to bring into commercial production. The battery previously exceeded 125 cycles with less than five percent capacity loss in March, 2024.

The milestone of 800 cycles was achieved without encountering the common issues that can complicate the market readiness of solid-state batteries. The battery, which uses a ceramic electrolyte separator was tested without compression and showed no signs of swelling or volume change.

It means the battery will not require compression, swell budget, an extensive cooling system, or heavy fire barriers when rolled out, according to ION.

Neil Ovadia, VP of Supply Chain at ION, spoke with ESS News about the company’s progress following previous coverage in 2022.

“The last two years have been transformational. We’ve grown from about 20 employees to over 75, expanded into two larger buildings, and broken ground on our pilot manufacturing facility,” said Ovadia.

“We’re focused on the defense and consumer products markets initially, with plans to transition into electric vehicles and grid storage as we reduce costs and increase energy density,” he added.

Technical milestones

The technical achievement of the battery itself was the real highlight, according to Ovadia.

“We’ve made big strides in our product’s cycle life. We went from proving 125 cycles in March to achieving 800 cycles by July. Importantly, these cycles were achieved at room temperature with no compression or additional aids, demonstrating the true potential of our solid-state technology,” he said.

Robert Whittlesey, Principal Technical Program Manager at ION, told ESS News the technical process behind the testing, and highlighted the significance.

“800 cycles is significant because that’s beyond most consumer electronics. That starts to get into EV and grid storage applications, and even space-based applications that require a high cycle life. So this is something that could be used for all applications.”

Ovadia added, “It’s a confluence of all the characteristics of that battery that got to 800 cycles. One thing that you find in solid-state batteries is this requirement for compression, this requirement for heat, this coddling of the battery to achieve those cycles. It’s meaningful when you look at it as a final product, it makes it more expensive, heavier, and takes away from the potential and promise of a solid-sate battery.

A chart supplied by ION of the C/3 testing (a charge-discharge rate of charging every three hours, discharging every three hours) shows low capacity loss:

Grid storage possibilities

ION’s advancements with its solid-state batteries are highly relevant for grid-scale applications, with the company recently awarded $20 million from the US government’s ARPA-E Scale-Up program, which aims to accelerate the development of larger format cells for grid storage.

Ovadia said, “We are focused on scaling up our technology to produce larger, more cost-effective batteries. This involves collaborating with manufacturing partners and leveraging our university research partnerships to enhance both the mechanical and electrochemical aspects of our technology.”

He further emphasized the robustness and safety of their technology, stating, “Our batteries are inherently safer, eliminating the risk of fires associated with lithium-ion batteries. This makes them ideal for large-scale energy storage deployments where safety is paramount.”

Whittlesey added, “Our technology is not only safer but also more efficient in various temperature conditions. Traditional lithium-ion batteries require significant infrastructure to maintain optimal temperatures, which incurs additional costs. Our batteries can operate effectively across a broader temperature range, reducing the need for such infrastructure.”

Ovadia said that the current BESS grid infrastructure generally consumes energy as a parasitic draw for cooling, something that can be eliminated with the ability to operate at higher temperatures without the dangers of lithium-ion batteries.

Furthermore, Whittelsey pointed out the recyclability of the solution over traditional battery products with graphite anodes.

More to come

ION recently secured a supply agreement and investment from Saint-Gobain in late 2023, one of the world’s largest ceramics, glass and material suppliers to boost its manufacturing capabilities.

“We are working with several other large multinational partners to produce significant quantities at gigawatt-hour scales and achieve global reach in manufacturing,” Neil said, adding that further “significant announcements” from the company are due in the coming quarters.

The relatively early-stage company previously raised $8 million in 2019, and $31 million Series A funding in 2022.

Harris names clean energy advocate Governor Tim Walz as VP pick The Harris-Walz ticket wins on climate, according to clean energy supporters.

Quantum algorithm for photovoltaic maximum power point tracking Researchers have developed a quantum particle swarm optimization algorithm for maximum power point tracking that reportedly generates 3.33% more power in higher temperature tests and 0.89% more power in partial shading tests compared to conventional swarm optimization algorithms.

New discovery paves the way for more efficient perovskite solar cells Researchers from University of Texas have used computational methods to study the formation of polarons in halide perovskites. The findings revealed topological vortices in polaron quasiparticles.

SunPower goes bankrupt The residential solar installer has filed for bankruptcy, among the largest in a series of major bankruptcies in the industry.

Atlanta Motorsports Park goes solar The motorsports club with an F1-style track is installing a solar array that is expected to power about 60% of its operations.

A drone’s eye view helps find the perfect solar site Drone Drafting brings an array of aerial sensors to project planning and engineering.

From pv magazine Global

Researchers at the University of Texas in Austin have explored the formation of polarons by examining the properties of halide perovskites.

Halide perovskites are used in applications such as photovoltaics due to their optoelectric properties. In the research paper “Topological polarons in halide pervoskites,” published in the Proceedings of the National Academy of Sciences, the scientists used supercomputers Lonestar6 and Frontera from the Texas Advanced Computing Center (TACC) to analyze these properties at the individual atom level.

The team developed EPW, an open-source Fortran and message-passing interface code that calculates properties related to electron-phonon interaction. The EPW code specializes in studying how electrons interact with vibrations in the lattice of a solid, which causes the formation of polarons.

“We found that electrons form localized, narrow wave packets, which are known as polarons,” Feliciano Giustino, one of the paper’s lead authors, told TACC. “These ‘lumps of charge’ – the quasiparticle polarons – endow perovskites with peculiar properties.”

“These polarons show very intriguing patterns. The atoms rotate around the electron and form vortices that had never been observed before. We suspect that this strange vortex structure prevents the electron from going back to the unexcited energy level,” Giustino explained. “This vortex is a protected topological structure in the halide perovskite lattice material that remains in place for a long time and allows the electrons to flow without losing energy.”

In the research paper, the scientists add that polarons take many different forms in halide perovskites, including small polarons, large polarons and charge density waves.

“We find that these emergent quasiparticles support topologically nontrivial phonon fields with quantized topological charge, making them nonmagnetic analog of the helical Bloch points found in magnetic skyrmion lattices,” the researchers said. “Our findings suggest that halide perovskites may be regarded as a class of quantum materials where electron-phonon couplings replace the traditional electron–electron interactions of correlated electron systems.”

From pv magazine Global

An international research team has developed a particle swarm optimization (PSO) algorithm based on quantum computing for real-time maximum power point tracking (MPPT) implementation in PV systems.

The scientists explained that the quantum version of the PSO algorithm capitalizes on the high speed of quantum computing and reduces the interval of random numbers in subsequent stages to avoid premature convergence. “A detailed implementation of the quantum aspect of the solution is provided using qubit states instead of classic particles and performing qubit spins using the y-axis rotation gates to perform the moves on the qubit states to search for the optimal solution,” they explained.

In quantum computing, a qubit or quantum bit is a basic unit of quantum information. It is the quantum mechanical analog of a bit in classical computing based on binary digits.

The proposed quantum particle swarm optimization (QPSO) algorithm is based on Schrödinger’s equation  – a differential equation that defines the behavior of wavefunctions in quantum mechanics.

“Simulating the behavior of human intelligence, rather than that of a flock of birds or a school of fish, necessitates capturing the thought processes of a complex social organism, which cannot be adequately described by a linear evolution equation,” the researchers said, seeking to describe the working principle of the algorithm. “It is believed that human thinking is as uncertain as a particle with quantum behaviors.”

The group tested the performance of the algorithm through Matlab Simulink software in a simulated PV array relying on four 213 W solar modules. It found the QPSO algorithm shows a strong ability to maintain performance close to that of conventional PSO across different environmental conditions. “It performs well in power optimization and maintaining system activity, as indicated by the power output and duty cycle values under both optimal and challenging conditions,” the academics added, noting that the proposed algorithm also requires “more prominent” computational demands.

They also found that, although the power achieved by the conventional PSO algorithm was approximately 0.15% higher than that attained by the QPSO algorithm under the same conditions, the QPSO was able to beat the conventional PSO in more challenging conditions.

“Specifically, the quantum algorithm generates 3.33% more power in higher temperature tests and 0.89% more power in partial shading tests,” they emphasized. “Additionally, the quantum algorithm displays lower duty cycles, with a reduction of 3.9% in normal operating conditions, 0.162% in high-temperature tests, and 0.54% in partial shading tests.”

The new algorithm was described in the study “Quantum maximum power point tracking (QMPPT) for optimal solar energy extraction,” published in Systems and Soft Computing. The research group included scientists from Algeria’s École Nationale Polytechnique and its École Nationale Supérieure de Technologies, Canada’s Université du Québec à Trois-Rivières, and the Norwegian Research Centre.

“Despite the classical algorithm’s marginal advantage in power output under normal conditions, the quantum algorithm illustrates superior performance across all other metrics, achieving higher power values and consistently lower duty cycle records, indicating more excellent general efficiency,” the scientists concluded. “Future work could explore adaptive algorithms that dynamically adjust to changing environmental conditions, enhancing efficiency and reliability.”

NASA installed the solar array for the Europa Clipper spacecraft, a robotic craft with a mission to reach Jupiter’s moon Europa by 2030. The large moon is one of 95 that orbit Jupiter, and it is studied closely due to its potential to host life in its global liquid ocean underneath its icy surface. 

Europa Clipper will be the largest spacecraft NASA has ever developed for a planetary mission. The craft is outfitted with large solar arrays that will serve as the primary power source for the mission. The arrays are large, as the Jupiter system is more than five times as far from the sun as Earth. 

The craft’s arrays are built as two five-panel wings. Each solar array measures 46.5 feet in length. To install the array, the team suspended the solar array on a gravity offload support system that helps support the weight of the solar array while it’s here on Earth. Next, NASA technicians will begin inspecting and cleaning as part of its assembly, test and launch operations. 

The array uses Azur Space 3G28 solar cells – with substrate panels from Airborne in the Netherlands, laid down by Leonardo in Italy and integrated into solar panels by Airbus Defence and Space in the Netherlands. The NASA Juice Mission also uses Azur Space 3G28 cells. 

The solar cells are designed for space travel, with self-annealing properties and the ability to operate under the intense radiation of space. More details can be found on an Airbus document.

The array is folded when launched and is designed for a passive deployment with spring-motorized hinges.

At launch, Europa Clipper will weigh approximately 13,000 lbs. Almost half of the weight will be fuel – nearly 6,000 lbs of propellant.

“Europa Clipper will launch in October 2024 on a SpaceX Falcon Heavy rocket from Kennedy Space Center in Florida. The spacecraft will fly by Mars, then back by Earth, using the gravity of each planet to increase its momentum. These so-called ‘gravity assists’ will provide Europa Clipper with the velocity needed to reach Jupiter in 2030,” said NASA.

From ESS News

Ambri has confirmed the closing of the sale of its assets in accordance with Section 363 of the Bankruptcy Code to a consortium of its lenders, as it prepares to take fresh steps toward commercialization of its long-duration storage technology.

Earlier this year, Ambri’s board, management and its lenders determined that a court-supervised 363 sale process was the best course to facilitate a comprehensive recapitalization in a bid to ensure long-term growth and profitability. The company filed for bankruptcy in May, blaming a challenging fundraising environment and thwarted plans to expand into manufacturing.

Now, the liquid metal battery storage startup has emerged with additional capital contribution from the Lender Consortium, whose bid was selected following a competitive sale process. The Lender Consortium comprises a group of Ambri’s pre-bankruptcy investors, including funds managed by each of Gates Frontier, Paulson and Co. Inc., Fortistar, and other investors.

“The team at Ambri has continued to make impressive progress towards a commercial long-duration battery system, including developing our third-generation cell product,” said David Bradwell, Ambri’s cofounder who is now taking the reins as the company’s new CEO.

“I am grateful for the dedication of our team and the support of our investors as we emerge as a leaner and more capital efficient organization. We look forward to offering our unique, safe, and low-cost commercial product to our customers at scale, to meet the strong customer demand for our battery systems, and for a cleaner energy future. As we embark on this fresh start with a stronger balance sheet and new capital, we are focused on positioning Ambri to play a leading role in the long duration energy storage market for the benefit of our stakeholders,” Bradwell said.

Founded in 2010 at MIT, Ambri has been working on building industrial-scale, liquid-metal batteries for over a decade. With Reliance Industries as one of its key investors, the company had plans to set up a large-scale battery manufacturing facility in India, in addition to building  a 140,000 square foot facility in Milford, Massachusetts.

As it filed for Chapter 11 bankruptcy, the company said it had seen strong demand for its technology from across the market, equaling the planned output of its factory in Milford, Massachusetts, for three years.

Ambri’s batteries feature a liquid calcium alloy anode, a molten salt electrolyte, and a cathode comprised of solid particles of antimony, enabling the use of low-cost materials and a low number of steps in the cell assembly process.

To continue reading, visit our ESS News website.

From pv magazine Global

A group of researchers at the Edith Cowan University in Australia has proposed a new methodology to determine the optimal size of large inverter-connected energy storage systems (ESSs) planned for emergency under-frequency response.

“Delivering the necessary response with minimal ESS capacity is advantageous for power system planning and operating a fleet of partially discharged ESS units,” the scientists said, noting that the proposed solution is also feasible at low costs. “Characteristics such as rise time, overshoot, and settling time of active power response can be controlled by adjusting specific parameters.”

In the paper “Optimizing grid-forming inverters to prevent under-frequency load shedding with minimal energy storage,” published in the Journal of Energy Storage, the researchers explained that ESS active power capacity can be used to minimize under-frequency load shedding (UFLS) schemes, which are generally activated during low-frequency events, shedding predetermined loads to prevent further frequency drops.

“Since UFLS events are rare, some transmission system operators do not require maintaining headroom to cater for large disturbances,” the research team said. “Thus, using ESS for emergency under-frequency response is a cost-effective option. Additionally, delivering the necessary response with minimal ESS capacity is advantageous for power system planning and operating a fleet of partially discharged ESS units.”

The academics also explained that the novelty of their work consisted of determining a battery’s minimum power rating for both virtual synchronous generators (VSGs) and droop control-based grid-forming (GFM) inverters. The ESS size, they specified, must be calculated to maintain the frequency within the standard operating range.

“The ESS size is optimized to prevent under-frequency load shedding following a trip of a large generator by maintaining frequency within frequency operating standard (FoS),” they also emphasized. “The calculation of control parameters and ESS size determination considers the multi-step duration and thresholds provided by the FoS. UFLS protection settings are designed based on the FoS and sizing ESS to achieve a fixed frequency will not provide the optimum ESS size.”

The proposed approach is based on a Hill climbing algorithm, which is a classic optimization technique in artificial intelligence that takes inspiration from climbing to the peak of a mountain. It works by increasing the elevation value to find the peak of the mountain or the best solution to a given problem. It terminates when it reaches a peak value where no neighbor has a higher value.

The group investigated a case study of a power system implemented via DIgSilent PowerFactory software.

The simulation showed that for GFM inverters, a decrease in the active power droop coefficient increases the active power output. This increase, however, is limited by current inverters’ constraints. As a result, the scientists suggest maintaining the active power droop coefficient at a value that can prevent instability resulting from inverters’ limitations while maximizing the active power output.

As for VSGs, they suggested maintaining the acceleration constant, which can reportedly strike a balance between the rate of change of frequency (RoCoF) and power oscillations. They noted that the acceleration time constant of the VSG controller is proportional to inertia and increasing it enhances inertia.

“For the case considered in this study, the minimum energy storage power rating for the virtual synchronous generator control is 85 MVA, while for droop control, the minimum storage capacity is 89 MVA,” the scientists concluded. “The results of this study should be helpful for power system planners to better harness the capabilities of energy storage systems.”

From pv magazine Global

PeroNova, a U.S.-based startup specializing in solar perovskite technologies, has developed a solar perovskite module for building-integrated photovoltaics (BIPV) and space applications.

“Our novel interfacial treatment technology enhances the stability and reliability of perovskite films in tests, and in fabrication conditions. Thermal cycling resistivity tests demonstrated over 80% of initial power conversion efficiency after 2,500 cycles,” a PeroNova spokesperson told pv magazine.

The company currently develops lab-scale four-terminal (4T) perovskite-silicon tandem solar cells and 900 cm2 mini perovskite modules. The lab-scale cells have reportedly an efficiency of around 30%, while the modules achieve around 28% for the 4-T tandem configuration, 22% for outdoor applications, and 18% for space.

Founded in 2023,  PeroNova plans to address the demand for solar power in portable electronics, space and rooftop markets. “Our team has diligently worked to create a best-in-class American-made product that offers affordable and reliable renewable energy globally,” said co-founder and CEO, Min Chen, in a statement.

The company also recently announced it is collaborating with unspecified U.S. real estate developers intending to “bring large-scale implementation” of BIPV and agrivoltaics across the country. It will also be working with undisclosed space tech companies.

PeroNova has secured five patents from the U.S. Department of Energy. It also recently appointed Peter H. Diamandis, a U.S.-based entrepreneurial investor and founder of the XPRIZE Foundation, to its advisory board where he will “advise on product design, commercialization strategy and investor relations.”

From pv magazine Germany

The Dutch research institute TNO has carried out a detailed life cycle analysis of floating PV systems on behalf of the International Energy Agency’s (IEA) Photovoltaic Power Systems Programme (PVPS). It shows that the floating systems have a slightly larger carbon footprint than land-based systems, mainly due to the additional components for the floating structure.

According to the experts, the carbon footprint of floating systems is around 15% larger than that of land-based systems with an east-west orientation. Compared to those with a south orientation, it is around 25%. However, floating systems have other advantages, such as the use of water instead of land and potential synergies with hydroelectric power plants.

According to their calculations, the CO2 emissions of floating systems are around 50 grams per kilowatt-hour of electricity generated, around seven times less than the current electricity mix in Germany and three to four times less than the EU-wide target for 2030.

For their analysis, the experts compared two real floating systems, one in Germany with a support structure made of high-density polyethylene (HDPE), and one in the Netherlands with a structure made of steel and HDPE, with hypothetical systems on land.

Recycling further reduces the carbon footprint

According to the experts, the carbon footprint of the floating system could be reduced with three measures: by using electricity from low-emission sources in the manufacture of the PV modules, by using recycled materials in the support structures and by recycling the HDPE at the end of its life cycle.

“Our study of two operating systems in Western Europe shows that floating photovoltaic systems on small inland waters can be a good complement to ground-mounted systems from the point of view of greenhouse gas emissions over the entire life cycle,” said Josco Kester, co-author of the study.

The researchers recommend further research into the environmental impact of floating photovoltaic systems, particularly with regard to the impact on aquatic ecosystems.

From pv magazine Global

Electricity demand around the world is expected to sky-rocket as we switch to electric-powered vehicles, heat pumps for our homes and pursue the vast digital transformation of society. Emerging nations are also expected to use an increasing amount of electricity as they industrialize and give their populations ever greater access to energy. While this massive switch over to electricity is expected to considerably reduce global greenhouse gas emissions and help in the fight against climate change, a mounting concern is that electricity grids won’t be able to cope with the increased demand.

Ringing the alarm bell

The International Energy Agency (IEA) started ringing the alarm bell with a report it claims is the first of its kind. Published in 2023, it states that the world must add or replace 80 million km of transmission lines by 2040, equal to all electricity networks installed globally today, to meet national climate targets and support energy security. The report identifies a large and growing queue of renewables projects waiting for the green light to be connected to the grid, pinpointing 1 500 gigawatts (GW) worth of these projects that are in advanced stages of development. This is five times the amount of solar photovoltaic (PV) and wind capacity that was added worldwide in 2022.

“The recent clean energy progress we have seen in many countries is unprecedented and cause for optimism, but it could be put in jeopardy if governments and businesses do not come together to ensure the world’s electricity grids are ready for the new global energy economy that is rapidly emerging,” says IEA Executive Director Fatih Birol. “This report shows what’s at stake and needs to be done. We must invest in grids today or face gridlock tomorrow.”

The World Economic Forum (WEF) also urges world leaders to take note. A recently published article by Marcus Rebellius, a member of the WEF managing board and an expert working for one of Europe’s biggest manufacturers of electricity and electronic devices, indicates that “while the generation of clean energy is important, digitalizing and expanding our electricity grids is also vital for the green transition. Only with smarter, digitalized and expanded electricity grids will we create a decarbonized, resilient and secure electrical network for a net-zero future.”

He warns that increasing the amount of electricity generated to meet the increasing demand is not the issue, but that the key problem is that the grid must be prepared to handle larger amounts of electric power. “Weak grid infrastructure, legacy issues and an ageing system can all hamstring the green transition irrespective of the latest floating wind turbines or gigantic solar arrays,” he says.

Pointing towards the solutions

Grids have become the bottlenecks of the energy transition. Rebellius points to several technology solutions that could help resolve those bottlenecks, such as digital twins, or the use of low-voltage networks. (For more on digital twins and the electricity network: Digital twins and the smart grid. For more on low-voltage networks, read Affordable, sustainable electricity for all.

Other options include massively increasing energy storage capabilities and the widespread deployment of smart grid technologies around the world. The IEC Electropedia defines the smart grid as an electric power system that utilizes information exchange and control technologies, distributed computing and associated sensors and actuators, for purposes such as the integration of the behavior and actions of the network users and other stakeholders as well as efficiently deliver sustainable, economic and secure electricity supplies. Adopting smart grid technology is viewed by many experts in the field as a cheaper solution for utilities than expanding or rebuilding legacy electricity grids, which would require massive investments.

Increased energy storage is a key requirement

At times of high electricity demand, extra electric capacity must be immediately available or the grid risks shutting down. One way of ensuring continuous and sufficient access to electricity is to store energy when it is in surplus and feed it into the grid when there is an extra need for electricity. Utilities around the world have ramped up their storage capabilities using lithium-ion supersized batteries, huge packs that can store anywhere between 100 to 800 megawatts (MW) of energy. California-based Moss Landing’s energy storage facility is reportedly the world’s largest, with a total capacity of 750 MW. These huge battery storage facilities are expected to increase as the demand for electricity soars.

Other reliable energy storage solutions are pumped hydro which currently accounts for more than 90% of the globe‘s current high capacity energy storage. Electricity is used to pump water into reservoirs at a higher altitude during periods of low energy demand. When demand is at its strongest, the water is piped through turbines situated at lower altitudes and converted back into electricity. Pumped storage enables to control voltage levels and maintain power quality in the grid.

Another option that is much talked about is to use electric vehicles (EVs) as a source of energy to deliver power to the grid. According to Frances Cleveland, who is a lead for cyber security and resilience guidelines in the IEC Systems Committee on Smart Energy (IEC SyC Smart Energy), “There are many research and pilot projects around the world that are deploying some form of bidirectional flow of energy (charging and discharging), either as vehicle-to-grid or vehicle-to-home with EVs, able to sell power to the main grid and even support the energy management of microgrids. One of the driving ideas behind these projects is to provide a means of storing energy in the EV from variable renewable resources, like solar and wind, for use at other times. This implies that EVs can actually be viewed as a type of distributed energy resource (DER).”

EVs can charge when renewable energy generation from wind or the sun is high or when there is a lower demand for electricity, for instance when people are sleeping. But when demand is high, or less energy is generated by the wind or the sun, the electricity stored in EV batteries could be put to contribution.

State of play for smart grids

According to the IEA, in a report that tracks the advancement of smart grids around the world, significant levels of investment in smart grid tech have been made in many countries around the world – even if much more needs to be done. Several examples are given, including the EU action plan Digitalisation of the energy system. The European Commission expects about EUR 584 billion (USD 633 billion) of investments in the European electricity grid by 2030, of which EUR 170 billion (USD 184 billion) would be for digitalization (smart meters, automated grid management, digital technologies for metering and improvement on the field operations). Another important source of information on the roll-out of smart grid tech is the Smart Grid Index, provided by a leading utilities group in the Asia Pacific and which is used by many experts involved in the field. According to Peter Jensen, the Chair of IEC TC 13 which prepares standards for smart meters, “The index provides an excellent view of the maturity of grid system operators in different regions of the world. It uses a grid modernization measure based on seven pillars,” he describes. (For more on IEC TC 13, read Peter Jensen’s interview in e-tech.)

IEC Standards to the rescue

IEC Standards help energy storage systems to interoperate and interconnect with the grid. They also pave the way for smart grid technologies to be used safely and efficiently. IEC TC 4 prepares standards for hydraulic turbines and has published IEC 60193 which specifies the requirements for pumped storage.

IEC TC 120 was set up to publish standards in the field of grid-integrated electrical energy storage (EES) systems to support grid requirements. The TC is working on a new standard, IEC 62933‑5‑4, which will specify safety test methods and procedures for lithium-ion battery-based systems for energy storage. IEC TC 69 prepares standards on electrical power/energy transfer systems for electrically propelled road vehicles drawing current from a rechargeable energy storage system. IEC TC 57 is the IEC committee that prepares core standards for the smart grid, notably the IEC 61850 series. They deal with substation automation, two-way information exchange, global control functions, renewable energy integration and cyber security, to name but a few. IEC TC 13 prepares key standards in the field of electrical energy measurement and control, for smart metering equipment and systems forming part of smart grids.

A subcommittee of IEC TC 8 prepares standards dealing with the integration of renewable energy systems in the grid. One of the four IEC Conformity Assessment (CA) Systems, IECRE (IEC System for Certification to Standards Relating to Equipment for Use in Renewable Energy Applications), is the internationally accepted CA system for all power plants producing, storing or converting energy from solar PV, wind and various forms of marine energy.

The IEC SyC Smart Energy helps to coordinate and guide the various efforts across these different IEC technical committees. It is for instance working on a document, IEC 63460, that will describe the architecture and use cases for EVs to provide grid support functions. Most of this standard will be concerned with identifying realistic EV charging and discharging configurations, and the communication and control between the various actors, grid system operators, aggregators, premises energy management and EV charging systems. The results from this document will hopefully help other IEC technical committees to take the grid-support capabilities of EVs into account as they develop their own standards.

The hope is that enough will be done in time to make sure the lights will be kept on as we move towards an all-electric and connected society. One certainty is that IEC Standards and conformity assessment will be called upon to play an ever-increasing role in ensuring we get there.

Author: Catherine Bischofberger

The International Electrotechnical Commission (IEC) is a global, not-for-profit membership organization that brings together 174 countries and coordinates the work of 30.000 experts globally. IEC International Standards and conformity assessment underpin international trade in electrical and electronic goods. They facilitate electricity access and verify the safety, performance and interoperability of electric and electronic devices and systems, including for example, consumer devices such as mobile phones or refrigerators, office and medical equipment, information technology, electricity generation, and much more.

Six states offer grants to help local governments automate solar permitting  Solar trade groups in Washington, Colorado and Minnesota advocated for grant programs to speed permitting for rooftop solar, using software such as SolarAPP+. Three other states also offer grants, with two requiring automated permitting.

Community solar needs to embrace urban rooftops and brownfields RE+ Mid-Atlantic solar conference panel: While developers prefer greenfield projects, state regulators target other project sites.

Reactive power management key to advancing grid stability  A look at the regulatory frameworks and practical applications, underscoring the essential role of reactive power management in maintaining a stable and efficient power grid.

U.S. Bureau of Land Management advances over 6 GW of solar projects  Once complete, the projects would generate enough electricity to power roughly 2 million homes.

U.S. clean energy tax credit market to reach $25 billion in 2024  A mid-year report from tax credit marketplace Crux showed that deal volume is expected to come in higher than previously expected at $20 to $25 billion this year.

Researchers at the Massachusetts Institute of Technology (MIT) have achieved a significant breakthrough in stabilizing a key component of perovskite solar cells. They have developed a method to synthesize Spiro-MeOTAD, a crucial material for charge transport, without using noble metals. This development led to the creation of a solar cell with an impressive 24.2% efficiency, although it experienced rapid degradation.

The research, led by Dr. Matthias J. Grotevent and Nobel Prize laureate Moungi G. Bawendi, demonstrated that their new method can produce a Spiro-MeOTAD material that remains stable even after 1,400 hours of testing at elevated temperatures (85°C) under continuous one-sun illumination. This durability is critical for materials exposed to the high temperatures and humidity typical of solar panel environments.

Their study, titled “Additive-free oxidized Spiro-MeOTAD hole transport layer significantly improves thermal solar cell stability,” underscores the potential of this new method. The researchers discovered that “even at low doping concentrations of 1%,” Spiro units could increase their electrical conductivity by orders of magnitude.

One of the key benefits of the material blend is its high glass transition temperature, which is above 115°C. This allows the solar cell to exhibit enhanced thermal properties, making it more suitable for use in high-temperature environments.

In all of this, the research team says that while the thermally stable Spiro unit is only in a solar cell that reaches 6% efficiency, they see a path via future research to stabilize the 24% efficiency solar cell.

According to the study, Spiro is currently an expensive material, priced online at $334 per gram. However, the researchers predict that the price could drop significantly with bulk orders reaching kilogram levels, potentially falling to $30 per gram or even $3/gram. When asked about the material’s cost by pv magazine USA, Dr. Grotevent estimated that a full-sized solar panel would require approximately 0.33 grams of Spiro, assuming a layer thickness of about 120 nanometers. This would result in a material cost of less than $0.003 per watt for a solar panel with an efficiency of over 20%, adding about $1.06 to the overall cost of the module.

Researchers are exploring three main approaches to deploying perovskites, which have so far seen limited use. The first method involves stacking perovskites atop silicon within the solar cell, a technique that has gained significant attention for its high efficiency, exemplified by Longi’s record-setting 34.6% perovskite-silicon tandem solar cell. The second approach, currently undergoing testing by GCL Perovskites, involves constructing nearly complete perovskite solar panels and layering them over similarly complete silicon solar panels to combine their outputs. The third approach features standalone perovskite panels without silicon, as demonstrated by the 1 MW China Three Gorges solar power facility.

Engineers from the University of Michigan have developed a new algorithm capable of designing optical multilayer film structures for applications, including solar cells.

OptoGPT (Opto Generative Pretrained Transformer) harnesses the computer architecture underpinning ChatGPT to work backward from desired optical properties to the material structure that can provide them.

The algorithm produces designs for multilayer film structures, consisting of stacked thin layers of different materials, reportedly within 0.1 seconds. Well-designed multilayer structures can maximize light absorption in a solar cell, and can also optimize design in other optical component manufacturers, such as telescopes. On average, OptoGPT designs contain six fewer layers than previous models, according to its creators. This means that its designs are easier to manufacture.

“Designing these structures usually requires extensive training and expertise as identifying the best combination of materials, and the thickness of each layer, is not an easy task,” said L. Jay Guo, professor of electrical and computer engineering at the University of Michigan. The model operates by treating materials at a certain thickness as words and encoding the associated optical properties as inputs. It seeks out correlations between these “words” and predicts the next word to create a “phrase” that achieves the desired property. “In a sense, we created artificial sentences to fit the existing model structure,” said Guo.

Guo is the corresponding author of “OptoGPT: A foundation model for inverse design in optical multilayer thin film structures,” a research paper that was recently published in Opto-Electronic Advances.

The paper says OptoGPT can “effectively deal with the non-trivial inverse design problem in multilayer structure … Combined with many proposed techniques, our model can unify the inverse design under different types of input targets under different incident angle/polarization, be versatile to different types of structures, as well as facilitate the fabrication process by providing diversity and flexibility.”

The researchers acknowledged that even though they used a large-scale dataset with 10 million samples for training, the dataset “only covers a small fraction of the expansive and complex design space associated with optical multilayer thin film structures.”

They said that because of the limitations in the training dataset, OptoGPT might not identify designs that fall outside the sampled design space.

“Close collaboration across multiple research groups is needed to obtain a better model for a more general and better photonic inverse design that expands to more complicated structures,” concluded the researchers.

A research team led by the Delft University of Technology in the Netherlands has outlined a roadmap for the optimization of monolithic perovskite/CIGS tandem solar cells and has found these PV devices may achieve a practical efficiency limit of 26.69%.

Using TCAD Sentaurus and GenPro4 modeling software, the scientists performed optical and electrical simulations of the materials and interfaces used in this type of tandem solar cell to better understand loss mechanisms and define a series of measures to improve efficiency.

The results were then calibrated by comparing simulated devices to three experimental devices: a tandem perovskite/CIGS solar cell; a single junction perovskite solar cell; and a single junction CIGS solar cell provided by Miasolé.

“The simulation platform is typically used in semiconductor research and development, as well as thin film and PV research. The CIGS sub-cell was based on on a state-of-the-art industrial device,” Delft University researcher, Paul Procel-Moya, told pv magazine.

The team noted that its work in this area differs from other numerical studies, as its focus is on the fundamental working mechanisms of the layers comprising the tunnel recombination junction (TRJ) and coupling-related loss calculations.

The study involved examining the energy alignment in TRJ layers to uncover the impact on external parameters of the baseline tandem solar cell, the exchange mechanisms between top and bottom cells, and the impact on the overall performance of the tandem system.

“Based on the main results, we propose a realistic roadmap for improvement of the tandem solar cell,” said Procel-Moya pointing to a four-pronged strategy towards improved performance. “We found in the simulation that the first stage should be fine-tuning the coupling tunneling junction between the two cells. It’s the first bottleneck.”

The first stage is to improve and optimize energy alignment at TRJ, while the second is to enhance the light management by minimizing the current mismatch between the sub-cells and reducing reflectance losses by adjusting perovskite and metallization thickness, for example. The third step is to improve the transport towards the tin oxide transport layer of the top cell. This step alone gave an estimated efficiency rise from 24.37 % to 25.13 %, according to the research. The fourth modification is to improve passivation in the top sub-cell.

Based on such modifications, the researchers calculated that the reference tandem cell could achieve an efficiency of 26.69 %. The team said that it expects that further “conversion efficiency gains are possible” by improving areas of the bottom cell, such as the absorber band gap energy and the passivation of the interface of CIGS and molybdenum layers.

Feedback received by Procel-Moya from other researchers currently experimenting at the lab scale confirmed that the TRJ focus was good advice. Looking ahead, the team will continue to do research on the physics of semiconductors PV and thin film with a focus on stability, studying reverse bias at the theoretical level, according to Procel-Moya.

The research appears in “Opto-electrical modelling and roadmap for 2T monolithic Perovskite/CIGS tandem solar cells,” published by Solar Energy Materials and Solar Cells. The team members were from the Netherlands institutions, Delft University of Technology, University of Twente, Eindhoven University of Technology, Netherlands Organisation for Applied Scientific Research (TNO), and U.S.-based MiaSole Hi-Tech Corp.

From pv magazine Global

Researchers at the Universiti Teknikal Malaysia Melaka have outlined a techno-economic optimization approach to define the appropriate power sizing ratio (PSR) for inverters used in grid-connected PV systems.

The PSR is the ratio of the inverter’s rated power to the total rated power of the connected PV modules and is crucial to maximizing energy yield and income. “An undersized inverter limits the system’s ability to convert all the generated DC power to AC power, leading to potential energy losses,” the scientists explained. “Conversely, an oversized inverter incurs higher initial costs without a proportional increase in energy production.”

The proposed methodology uses a pattern search algorithm (PSA), which is an optimization technique commonly utilized for problems with complex relationships and potentially noisy data, to ensure an accurate representation of real-world inverter behavior.

The model considers radiation, convection thermal representations, and real-world weather data. It also takes into account data from the inverters’ datasheets to evaluate the efficiency curve of the devices. From this curve, it then extracts key points to identify efficiency values between the chosen data points.

“The model undergoes a calibration phase where the efficiency curve points are iteratively adjusted by the PSA until the estimated/modeled values closely match the actual measurements obtained from the real system over a predefined period,” the group explained. “This calibration step guarantees that the model accurately reflects the real-world performance of the system.”

According to the scientists, the model can estimate the annual power yield of a solar array for each iteration step through various DC/AC power ratios, which in turn allows PV system owners to find the optimized ratio that maximizes energy production.

They also warned that the proper selection of the optimal PSR needs to be complemented by economic considerations relating to inverter costs, operation and maintenance, inverter complexity, and monitoring systems. “It’s important to note that the cost function doesn’t directly represent monetary value but rather a relative measure of economic performance,” they stressed. “The actual economic feasibility would depend on specific system costs and electricity prices.”

The novel methodology was presented in the study “Techno-economic optimization of photovoltaic (PV)-inverter power sizing ratio for grid-connected PV systems,” published in Results in Engineering.

“Future research directions involve exploring the integration of additional factors into the model,” the research team concluded. “These factors could include advanced weather forecasting capabilities, dynamic pricing schemes, and potential application to different types of PV systems or even broader renewable energy systems.”

From pv magazine Global

An international research team has outlined a new design for solar cells based on antimony trisulfide (Sb₂S₃) that can reportedly result in 30% higher efficiency compared to existing Sb₂S₃ solar cell concepts.

This kind of cell typology has, so far, been far from reaching commercial production, due to the low crystallinity and high resistivity of the Sb₂S₃ film, which affects the device’s performance in terms of efficiency. Sb₂S₃, however, has a good bandgap, ranging from 1.70 to 1.90 eV, and a remarkable light absorption coefficient.

In the study “Scrutinizing transport phenomena and recombination mechanisms in thin film Sb₂S₃ solar cells,” published in scientific reports, the scientists explained that Sb₂S₃ devices can achieve an efficiency of up to 26% under the radiative limit, but defects in the absorber material commonly decrease it to around 8%.

“The novelty of this work lies in its detailed theoretical examination of Sb₂S₃ solar cells, specifically focusing on the intricate interplay of various transport mechanisms such as tunneling-enhanced recombination, Sb₂S₃/CdS interface recombination, and non-radiative recombination,” they added.

Their analysis showed that two of the key factors influencing Sb₂S₃ cell performance are cadmium sulfide (CdS) layer doping and thickness, which have an impact on the device’s open-circuit voltage and short-circuit current. Furthermore, they found that bandgap and electron affinity have an influence on light absorption and charge transfer, respectively.

They also explained that fine-tuning the CdS layer with a high bandgap allows a greater number of photons to effectively penetrate the absorber. “Simultaneously, a lower electron affinity plays a crucial role in improving key parameters like short-circuit current and open-circuit voltage, ultimately boosting the overall conversion efficiency of the solar cell,” they emphasized. “This enhancement stems from the establishment of an optimal band alignment at the CdS/Sb₂S₃ interface, reducing the barrier height and facilitating the smooth passage of electrons from the absorber layer to the CdS.”

The group also analyzed the effect of bulk traps located at the interface between CdS and Sb₂S₃ and found that the influence of these interfacial defects may have an impact on carriers’ minority lifetime, diffusion length, and surface recombination velocity. “Scientists can develop strategies to mitigate their adverse effects,” the academics said. “This includes engineering interface structures, optimizing material properties, and enhancing passivation techniques to minimize recombination and improve the reliability of the CdS/Sb₂S₃ interface, ultimately leading to more efficient and robust solar cell designs.”

The team outlined a simple solar cell architecture with the proposed optimized parameters. The device was based on a substrate made of glass and indium tin oxide (ITO), a CdS layer, an Sb₂S₃ absorber, and a gold (Au) metal contact.

Simulated and tested under standard illumination conditions, the device showed a power conversion efficiency of 11.68%, an open-circuit voltage of 1.16 V, a short-circuit current density of 9.5 mA cm⁻², and a fill factor of 54.7%. “Notably, the optimized Sb₂S₃ solar cell not only exhibits superior performance but also demonstrates enhanced reliability in mitigating interfacial traps at the CdS/Sb₂S₃ interface, thanks to improved band alignment control and parameter optimization,” the scientists said.

The research group comprised scientists from Algeria’s research institute Laboratory HNS-RE2SD, the Bangladesh Atomic Energy Commission, Mexico’s Universidad Autónoma de Querétaro, India’s Saveetha Institute of Medical and Technical Sciences and the Kalasalingam Academy of Research and Education, as well as the King Saud University in Saudi Arabia and the Yeungnam University in South Korea.

Solar corporate funding drops to $16.6 billion in H1 High interest rates, an uncertain rate trajectory and timeline, increasing trade barriers, supply chain challenges, concerns about the presidential election’s impact on the sector, and constantly evolving trade policies have created a climate of uncertainty.

First Solar commissions 1.3 million square-foot R&D facility The Jim Nolan Center for Solar Innovation in Lake Township, Ohio includes a high-tech pilot manufacturing line allowing for the production of full-sized prototypes of thin film and tandem PV modules.

Intersect Power closes $837 million in financing for three battery systems in Texas Each project comprises 86 Tesla Megapacks and will provide a capacity of 320 MWh of battery storage with a two-hour duration.

S&P Global launches daily spot market price assessment for solar panels The tool has been billed as the world’s first independent daily spot market price assessment for solar panels. S&P Global says it has been launched to aid transparency in technology pricing as solar modules become increasingly commoditized.

Generac awarded up to $200 million from DOE for solar and storage in Puerto Rico The funds seek to build energy resilience in Puerto Rico, where hurricanes and other extreme weather frequently leave residents without power.

North American solar power purchase agreements rise 3% in Q2 LevelTen Energy released its quarterly PPA Price Index Report, showing an increase in prices following a modest drop in Q1.

First Solar, Inc. commissioned its new research and development (R&D) innovation center in Lake Township, Ohio, which the company says is the largest facility of its kind in the Western Hemisphere.

The Jim Nolan Center for Solar Innovation is dedicated to the late James “Jim” F. Nolan, a former member of First Solar’s Board of Directors and the architect of the company’s cadmium telluride (CdTe) semiconductor platform.

According to a study by the National Renewable Energy Lab (NREL), in 2023 CdTe represented  about 16% of the U.S. solar market. First Solar is a leader in CdTe technology and differentiates itself not only by the use of the thin film technology, but also by its vertically integrated manufacturing process, domestic production and commitment to responsible solar. At the company’s California Technology Center (CTC) in Santa Clara, First Solar recently achieved a 23.1% efficient CdTe cell, a new world record certified by NREL.

“Thin films are the next technological battleground for the solar industry because they are key to commercializing tandem devices, which are anticipated to be the next disruption in photovoltaics,” said Mark Widmar, chief executive officer, First Solar. “While the United States leads the world in thin film PV, China is racing to close the innovation gap. We expect that this crucial investment in R&D infrastructure will help maintain our nation’s strategic advantage in thin film, accelerating the cycles of innovation needed to ensure that the next disruptive, transformative solar technology will be American-made.”

The new research facility covers 1.3 million square feet and includes a high-tech pilot manufacturing line allowing for the production of full-sized prototypes of thin film and tandem PV modules. Prior to the commissioning of the Jim Nolan Center, First Solar was using a manufacturing line at its Perrysburg, Ohio facility for product development efforts. With a dedicated R&D center, First Solar expect to “accelerate innovation cycles.”

The company reports that it will have approximately a half-billion dollars invested in R&D and that building out R&D infrastructure will create approximately 300 new jobs by 2025, the majority of which will be located at the Jim Nolan Center.

First Solar is also involved in perovskite solar development after announcing last year the acquisition of Evolar, the Swedish perovskite specialist. First Solar said in a statement that the acquisition will accelerate the development of next generation PV technology, including high efficiency tandem devices. It aims to integrate Evolar’s know-how with its existing research and development streams, intellectual property portfolio, and expertise in developing and commercially scaling thin-film PV.

In addition to R&D planned at the Jim Nolan Center, the company expects to also commission a perovskite development line at its Perrysburg, Ohio, campus in the second half of 2024.

First Solar reports it has invested almost $2 billion in R&D, operates laboratories in Santa Clara, California, and Perrysburg, Ohio, in the US, and Uppsala in Sweden.

At the end of 2023 First Solar had 16.6 GW of annual global nameplate manufacturing capacity and is expected to achieve over 25 GW of capacity by 2026. First Solar expects to commission new manufacturing facilities in Alabama in the second half of 2024 and Louisiana in the second half of 2025, bringing its total U.S. nameplate capacity to 14 GW by 2026.

U.S. manufacturer Peak Energy announced it has secured a $55 million Series A funding round to scale production of grid-scale sodium-ion batteries.

The funding round was led by Xora Innovation, a investing platform of Temasek. The Series A also included participation from Eclipse, strategic partner TDK Ventures, and new investors Lachy Groom, Tishman Speyer, TechEnergy Ventures, Doral Energy-Tech Ventures and DETV-Scania Invest.

Sodium-ion batteries are a proven battery chemistry that offers some advantages in cost, supply chain security, and safety when compared with conventional lithium-ion batteries.

(Read: “Sodium-ion batteries – a viable alternative to lithium?”)

Peak Energy said sodium-ion batteries will help support the transition to renewable energy by storing and dispatching electricity from intermittent sources like solar and wind. With Wells Fargo forecasting a 20% increase in U.S. electricity demand by 2030 after a decade of flat demand, more storage is needed to ensure renewable energy can deliver reliable power when it is needed most, rather than relying on new natural gas reserve power.

“As energy demand grows, we must capitalize on the potential of renewables to provide dependable, inexpensive energy to fuel a new era of technological advancement. Utility-scale storage powered by sodium-ion is the answer to securing this future on a resilient, decarbonized grid,” said Landon Mossburg, chief executive officer, Peak Energy.

Peak Energy said the new capital will help it enter the next phase of growth, launching the first full-scale production of sodium-ion storage in the U.S. The company’s battery technology is set to be deployed with “a select group of six premier customers” in its pilot program in 2025. The customer base includes three of the five largest Independent Power Producers and electric utility companies in the nation.

The company launched from stealth less than a year ago with a $10 million seed round and the addition of Apple and Tesla veteran Liam O’Connor as co-founder and chief operations officer.

Peak Energy said it is on track to break ground on its first domestic “giga-scale” sodium ion battery in 2027.

PJM Interconnection, which provides transmission from Chicago to New Jersey, said it will launch a stakeholder engagement process in August to “help inform inputs” into scenario analyses for long-term regional transmission planning.

PJM and other transmission providers are required by the Federal Energy Regulatory Commission’s (FERC’s) Order No. 1920 “to plan for the transmission we know we will need in the future,” FERC has explained. Scenario analyses are part of the planning process.

PJM announced the stakeholder engagement process in its response to a letter from three renewables-focused trade groups and other entities asking PJM to “shift its current long-term regional transmission planning proposal to focus on Order No. 1920 directives.”

One of the trade groups, American Council on Renewable Energy, said last year that 167 GW of large-scale solar, wind and storage projects awaited interconnection studies by PJM. The group said that a lack of transmission capacity due to “insufficient” transmission planning is a “root cause of the unprecedented backlog” of interconnection requests across grid operators nationwide. Trade groups Americans for a Clean Energy Grid and Advanced Energy United also signed the letter.

In the works

PJM issued a regional transmission expansion plan last year that “identified” 93 transmission projects at a cost of $180 million to support generation seeking interconnection, and 48 new baseline projects at an estimated cost of $6.6 billion to maintain grid reliability, said a FERC staff report in March, while PJM “evaluated” 227 supplemental projects put forward by transmission owners that would cost $2.4 billion.

A major “national interest” transmission corridor in the PJM region has been proposed by the U.S. Department of Energy (DOE) that would help PJM “maintain and improve reliability, lower consumer costs, and meet future generation and demand growth,” DOE said.

Nationwide, a DOE transmission needs study found that 54,500 GW-miles of within-region transmission must be added for a clean grid under “the most likely power sector future.”

“Ultimate directives”

The trade groups expressed a concern in their letter that “PJM’s recent rehearing request to FERC suggests that PJM may seek to avoid implementing some important components of Order No. 1920.”

Responding to that concern, PJM said its rehearing request sought “flexibility” to implement the FERC order’s requirements “in a less prescriptive way such that PJM can tailor its approach to reflect its unique circumstances and regional needs.” PJM said that FERC will rule on “the numerous rehearing requests filed,” and said it “will comply in full with [the] Commission’s ultimate directives.”

States’ role

FERC said that its order “expands states’ pivotal role throughout the process of planning, selecting, and determining how to pay for transmission facilities.”

The governors of four states served by PJM—Illinois, Pennsylvania, Maryland and New Jersey—said in a letter to PJM last month that transmission planning is important in “developing large-scale low-and-zero emission energy resources.”

The governors said they “applaud” the grid operator’s steps to prepare for scenario discussions “that include each of our states,” and look forward to extensive engagement with PJM management and stakeholders “in shaping regional transmission planning and cost allocation approaches.”

All 13 states served by PJM had called for the grid operator to make faster progress on interconnection of renewable generation projects in 2022, in comments to FERC from the Organization of PJM States, Inc. (OPSI).

State do not have representation in PJM’s governance structure, but PJM says in a website document that it “works closely with state regulatory commissions to identify and respond to local matters,” explaining that OPSI, made up of the state commissions in PJM’s region, acts as a “liaison group” to PJM and its members.

Sixty-nine state legislators from 10 states served by PJM called this week for the grid operator to “work without delay” to implement FERC Order No. 1920, saying that “effective implementation” of the order is “critical to our responsibility to ensure that our constituents have access to reliable, affordable and clean electricity,” in a letter organized by the National Caucus of Environmental Legislators.

From pv magazine Germany

A team from Saarland University in Germany has secured funding from the European Innovation Council (EIC) Pathfinder program to develop elastocalorics heating and cooling technology as an alternative to heat pumps and air conditioning systems.

The €4 million ($4.36 million) EIC Pathfinder Challenge research project aims to develop a prototype for decentralized room air conditioning within three years. According to the research team, the technology is rated by the World Economic Forum (WEF) as one of the “TOP Ten Technologies 2024.” The US Department of Energy and the European Commission have also declared it to be the most promising alternative to conventional heating and cooling.

The solid-state heating and cooling process is based on transporting heat into or out of a room by loading and unloading a so-called shape memory material, for example in the form of wires. The material absorbs heat when it is loaded, for example when it is pulled, and releases it again when the load is removed.

The researchers, led by elastocalorics pioneer Paul Motzki, are using the superelastic nickel-titanium alloy for this purpose. Materials made from this alloy return to their original shape after deformation because they have two crystal lattices and thus two phases. While water, for example, assumes the solid, liquid and gaseous phases, in nickel-titanium both phases are solid but merge into one another.

Motzki, who holds a bridge professorship between Saarland University and the Center for Mechatronics and Automation Technology (ZeMA), is leading a consortium as part of the SMACool project, which is now funded by the EIC. The consortium also includes the universities in Ljubljana and Naples, as well as Irish company Exergyn.

The aim is to jointly develop a prototype of an air conditioning unit for residential buildings. Fresh air will flow in through narrow ventilation slots in the external walls and be heated or cooled as required until the desired temperature for the room behind is reached.

“With our technology, we don’t want to heat and cool houses with a central system, but rather each individual room in a decentralized and individual way,” said Motzki.

The compact unit to be developed could also be installed directly in new buildings with ventilation systems in the future.

With an electrocaloric system, temperature differences of around 20 C can be achieved when cooling and heating. The technology could become an alternative to conventional cooling and heating methods, as it does not require coolants and uses considerably less energy.

“The efficiency of elastocaloric materials is more than ten times higher than today’s air conditioning or heating systems – they will require significantly less electricity,” said Motzki.

Teams in Saarbrücken, Germany, have spent around 15 years researching and developing a technology using thin sheets of nickel-titanium to achieve optimal cooling or heating effects in circulatory systems. This includes creating a cooling and heating demonstrator and a continuously operating refrigerator.

From pv magazine Global

A review of indoor PV cell technologies by an international research team documents over 250 large area and small area commercial and laboratory devices. It covers organic, dye-sensitized, and perovskite devices, as well as crystalline and amorphous silicon, III-V semiconductor, chalcogenide, and emerging lead-free alternative cells.

“We observed that the interest in the field was really taking off, so we believed a comprehensive review on all indoor PV technologies was due,” the review’s co-author Giulia Lucarelli told pv magazine.

The review also includes a discussion about applications, recent progress, and strategies used to design more stable, highly efficient cells that operate at very low light levels.

“We have provided the performance details of the indoor PV devices at 200 lx and 1000 lx illuminance,” corresponding author, Thomas M. Brown, told pv magazine, explaining that most homes have a 200 lx illuminance, whereas 1000 lx is typical in very well-lit environments like supermarkets.

Brown pointed out that one of the initial high-volume market niches for indoor PV has been electronic supermarket shelf labels. Other applications are emerging, such as Internet-of-Things products, where PV is seen as enabling a “fit and forget” approach, where a product is installed once with no further maintenance required. “Think of applying a temperature or other type of sensor in your home and leaving it there to operate without ever having to replace batteries,” said Brown.

Cell technologies covered in the review range from crystalline and amorphous silicon to III-V semiconductor and chalcogenide devices, as well as organic, dye-sensitized, perovskite, and lead-free alternative devices.

Looking at the power conversion efficiency (PCE) and maximum power density (MPD) the team made several observations. For example, it said that it was “obvious that irrespective of the indoor lamp type or intensity”, perovskite solar cells have “outdone” other PV technologies both in terms of efficiency and output power.

The team observed that organic photovoltaic devices (OPV) performed well under light-emitting diodes (LED), while dye-sensitized solar cells (DSSC) outperformed in fluorescent light (FL). But it also cautioned there was only a limited number of reports making it “difficult” to draw any conclusions.

“Among the established technologies, compound and thin film semiconductors in recent years have shown considerable improvement in performance, with the former delivering high efficiency and output power,” stressed the team. “The lead-free alternatives have just entered the indoor PV arena and have managed to deliver the highest efficiency of around 18 % with a tin-based perovskite.”

Standards for performance reporting were discussed, particularly the need for a protocol for measurement in standard light source spectrum and a standard illuminance level, or levels. “The most utilized currently are 200 lx and 1000 lx so both should continue to be reported,” said the scientists.

They explained that MPD reporting for 200 lx and 1000 lx illuminance is important for product developers designing energy harvesting solutions and products that operate in a range of lighting conditions. “MPD is a more immediate metric since product developers who wish to integrate PV in their items know exactly what is coming out of the PV device,” co-author Abhisek Chakraborty told pv magazine. 

Brown added that indoor lamp spectra are diverse, ranging from LED, to compact fluorescent and lamp bulbs with different color temperatures. “We only have 1 sun but a myriad of indoor light sources,” said Brown.

They also noted that whereas crystalline silicon, thin film, and new PV technologies have stability protocols for outdoor applications, and accelerated stress tests, these are “still lacking” for PV-designed indoor environments only.

In summarizing the findings, the team noted indoor laboratory efficiencies for emerging PV technologies are reaching efficiencies in the range of 35 – 45 % under 200 lx and 1000 lx. “The corresponding electrical power densities are in the range of 20 – 25 μW cm-2 at 200 lx and the range of 120 – 150 μW cm2 at 1000 lx illuminance,” it said.

There is work to do in indoor PV stability and more investigation under continuous indoor illumination, noted the team, pointing out that improvements can be achieved “through the right choice of materials, device design and scalable manufacturing” processes.

“The goal is to improve performance while increasing stability and reducing the cost of not only the indoor devices but their integration capabilities with the electronic products they aim to power,” it said.

“As mentioned earlier there is a question of different reporting, illumination, and measurement conditions for indoor PV,” Brown said, referring to the future direction of the research. “We are trying to present some best practices for this. We are also working on some national projects related to developing perovskite PV indoors via more sustainable materials and fabrication processes.”

The review appears in “Photovoltaics for Indoor Energy Harvesting,” published by Nano Energy. The researchers were from Italy’s Tor Vergata University, the Netherlands Organization for Applied Scientific Research (TNO), the Fundación Escuela Tecnologica in Colombia, and Jain University in India.

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Solar tariffs could “unintentionally cede U.S. leadership in the solar industry”  A report from Clean Energy Associates (CEA) and the American Council on Renewable Energy shows how antidumping and countervailing duty (AD/CVD) tariffs create cost issues not just for imported solar panels, but for U.S.-made solar panels as well. 

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Residential PV power forecasting method based uniquely on direct radiation Researchers in Spain have created a novel PV forecasting method that uses only direct radiation as a parameter. They found it to be “comparable, if not superior” to four established forecasting techniques. The method could help homeowners with PV systems decide when to use electricity-intensive appliances and cleaning systems.

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Amazon hits 100% renewable energy goal seven years ahead of schedule The retail giant matched 100% of the electricity used in its operations with investments in renewable energy in 2023.

All-perovskite tandem solar cell based on tin-lead perovskite achieves 27.8% efficiency Scientists in the United States have fabricated an all-perovskite tandem solar cell that reportedly shows reduced interfacial energy loss in the cell’s top device. It was built with a hole transport layer based on a compound known as P3CT that was doped with lead iodide.

From pv magazine Global

A group of researchers led by the University of Toledo in the United States have fabricated an all-perovskite tandem solar cell with a wide-band-gap top cell based on tin-lead (Pb-Sn) perovskite and a low-band-gap bottom cell relying on a conventional perovskite substrate.

“The technology readiness level (TRL) of the tandem device investigated in this study is still low at TRLs 2-3,” the research’s corresponding author, Zhaoning Song, told pv magazine. “Our work, however, proves the feasibility of enhancing the stability of all-perovskite tandem solar cells, but more work needs to be done to apply this technique to industrial production.”

The key feature of the tandem cell is the top device’s hole transport layer (HTL), which was fabricated with a Pb-doped compound known as poly[3-(4-carbox- ybutyl)thiophene-2,5-diyl] (P3CT), a material that reportedly offers excellent stability and relatively high hole mobility.

“We introduce Pb doping to increase its work function and minimize the energy level offset with the Sn-Pb perovskite,” the academics explained, noting that P3CT represents a valid alternative to commonly used PEDOT-PSS. “The Pb dopants also provide nucleation sites to enable high-quality Sn-Pb perovskite film growth.”

The group built the top cell with a substrate made of indium tin oxide (ITO), the novel HTL, the Sn-Pb perovskite absorber, an electron transport layer (ETL) based on buckminsterfullerene (C60), a bathocuproine (BCP) buffer layer, and a silver (Ag) metal contact.

The champion cell built with this architecture achieved a power conversion efficiency of 22.7%, an open-circuit voltage of 0.884 V, a short-circuit current density of 32.0 mA cm2, and a fill factor of 80.3%. It was then combined in a tandem device with an 18.7%-efficient bottom cell based on a perovskite absorber with a bandgap of 1.7 eV, an HTL made of a phosphonic acid called methyl-substituted carbazole (Me-4PACz) and an ETL relying on C60.

The champion P3CT-based tandem achieved an efficiency of 27.8, an open-circuit voltage of 2.147 (2.146) V, a short-circuit current density of 15.7 mA/cm2, and a fill factor of 82.6%.

“The P3CT-based tandems also show a higher average efficiency of 27.0% than PEDOT: PSS-based devices, proving excellent reproducibility of the high-efficiency tandems with the P3CT-Pb HTL,” the group emphasized. “Doping P3CT with Pb cations reduced the valence band offset with Sn-Pb perovskite and provided nucleation seeds for enhancing perovskite crystallization, resulting in improved film quality.”

The P3CT-based tandem was also found to retain around 97% of its initial efficiency after 1,000 h.

According to Song, the cost of the doping technique is almost negligible, as the lead iodide material used for doping is the same source material used for producing the perovskite absorber layer, and only a trivial amount is needed for doping. “Yet, it is worth noting that the polymer hole-transport material used in this study is still expensive due to its complexity of synthesis and limited production scale,” he further explained.

The new cell technology was introduced in the study “Suppressed deprotonation enables a durable buried interface in tin-lead perovskite for all-perovskite tandem solar cells,” published in Joule. “Our molecular design strategy for stabilizing the perovskite/HTL interface provides a direction for achieving efficient and stable all-perovskite tandem solar cells,” the team concluded.

From pv magazine Global

A research group led by Spain’s Valencia Polytechnic University has developed a novel single-parameter power forecasting method for residential PV installations.

The proposed approach defines interval prediction data rather than absolute figures, the scientists said, noting that it acknowledges and transparently communicates the natural variability in solar PV power generation.

“Opting for a single-parameter-focused model was a strategic decision aimed at simplifying the forecasting process,” highlighted the research group. “While multi-parameter models might offer more nuanced insights, they often entail increased computational complexity and resource demands. Our streamlined model promises ease of integration and user-friendliness, crucial for residential users and small-scale PV installations.”

The core aspect of the novel method is the selection of similar days in the past regarding direct radiation to forecast the power generation of a given day. A confidence level of 80% and a total of 10 similar days are selected for each prediction. After identifying similar days, the method uses a quantile-based approach to establish the prediction intervals, setting an upper and lower limit. In statistics, quantiles are used to divide the range of a probability distribution into continuous intervals with equal probabilities.

The system was trained and tested using a case study of a residential installation in Spain, which consists of 12,450 W panels and a 5 kW inverter for self-consumption, all of which installed in 2018. Hourly PV generation was recorded during the years 2019, 2020, 2021, and 2022. Hourly meteorological data for the area was obtained from the database Open Meteo.

The forecasting technique was used to predict PV power generation in 2020, based on the algorithm to search for similar days always within a range of two years before the target day. In the same period, it was compared to four classical forecasting methods: linear regression model (Alt1); gradient boosting regressor (Alt2); gradient boosting with lags (Alt3); and long short-term memory (LSTM) network (Alt4).

“The models’ performance was evaluated using Key Performance Indicators (KPIs) like prediction accuracy, prediction interval width, actual confidence level, and mean error. This thorough approach ensured a balanced assessment, emphasizing the strengths and limitations of each method,” said the researchers.

The proposed method achieved a mean absolute error (MAE) of 0.1490 kW, a mean squared error (MSE) of 0.0917 kW2, a root mean squared error (RMSE) of 0.3029 kW, an average width of intervals (AWI) of 0.3365 kW, a coverage probability (CP) of 91.55%, and an overall interval error (OIE) of 0.3789 kW. Alt1 showed an MAE of 0.3374 kW, an MSE of 0.2428 kW2, an RMSE of 0.4928 kW, an AWI of 0.9312 kW, a CP of 78.69%, and an OIE of 0.4117 kW.

Alt2 had an MAE of 0.2558 kW, an MSE of 0.2044 kW2, an RMSE of 0.4521 kW, an AWI of 0.7464 kW, a CP of 80.12%, and an OIE of 0.4031 kW. Alt3 recorded an MAE of 0.1379 kW, an MSE of 0.0768 kW2, an RMSE of 0.2771 kW, an AWI of 0.4890 kW, a CP of 91.72%, and an OIE of 0.2355 kW. Alt4 showed an MAE of 0.1282 kW, an MSE of 0.0684 kW2, an RMSE of 0.2616 kW, an AWI of 0.3522 kW, a CP of 80.72%, and an OIE of 0.2642 kW.

After analyzing the numerical results, the researchers verified how the proposed approach could help PV system owners achieve energy savings. According to their results, the average monthly energy bill decreased from $47.96 to $40,67, as energy imported from the grid decreased by 45.79 kWh, from 278 kWh to 232.21 kWh.

“By simply adjusting the operation schedules of the pool’s filtration system, the washing machine, and the dishwasher to align with peak solar production times, homeowners have been able to harness more solar energy, reducing reliance on the grid and decreasing the overall energy costs,” they concluded. “With advancements in home automation technology, even greater results can be achieved.”

Their findings were presented in “Interval-based solar photovoltaic energy predictions: A single-parameter approach with direct radiation focus,” published on Renewable Energy. The group comprised scientists from Spain’s Valencia Polytechnic University, the University of Valencia, and Ecuador’s Politecnica Salesiana University.

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World’s first anode-free sodium solid-state battery Researchers at the Laboratory for Energy Storage and Conversion have created a new sodium battery architecture with stable cycling for several hundred cycles, which could serve as a future direction to enable low-cost, high-energy-density and fast-charging batteries.

Researchers build 16%-efficient mini perovskite solar module resistant to UV light-induced degradation A U.S. research team has built a 15 cm2 perovskite solar module with improved stability and efficiency thanks to a polymer hole transport layer that reportedly improves the panel stability and efficiency.

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Organic solar cell gains counterintuitive efficiency boost from entropy A research team at the University of Kansas found that organic semiconductors known as non-fullerene acceptors demonstrate a high solar cell efficiency due to a reversed heat flow.

A team of researchers at the University of Kansas have studied a counterintuitive effect in organic semiconductors that may lead to solar cell efficiencies competitive with traditional silicon solar panels. The research is published in Advanced Materials.

Researchers worldwide are actively testing alternative materials to silicon for manufacturing solar cells. While silicon offers strong efficiency and durability, there are other more abundant materials that could serve as lower-cost alternatives. Silicon is also rigid, where some photovoltaic materials have demonstrated an ability to be flexibly deposited on uneven surfaces in thin layers.

One type of material researchers are developing are called “organic” semiconductors. These carbon-based semiconductors are Earth-abundant, inexpensive, and potentially more environmentally friendly.

“They can potentially lower the production cost for solar panels because these materials can be coated on arbitrary surfaces using solution-based methods – just like how we paint a wall,” said Wai-Lun Chan, associate professor of physics and astronomy at the University of Kansas.

Chan said these organic materials can be tuned to absorb light at specific wavelengths. The materials can be used to create transparent solar panels or panels with specific colors, making them a useful fit for integrating with sustainable buildings.

Organic semiconductors are already used today in display panels of consumer electronics such as cell phones and TVs. They have not yet been commercialized in PV, as their light-to-electricity conversion efficiency sits around 12%, about half as powerful as traditional silicon solar panels.

However, the use of a new class of materials called non-fullerene acceptors (NFA) may help bridge the gap in efficiency. Organic solar cells made with NFAs have demonstrated efficiencies closer to 20%.

The significant boost in performance from NFAs occurred from a counterintuitive effect. The team found that some of the excited electrons in the material gained energy from the environment, rather than losing it via entropy.

“This observation is counterintuitive because excited electrons typically lose their energy to the environment like a cup of hot coffee losing its heat to the surrounding,” said Chan.

The researchers believe that the energy gain may be due to a quantum effect in electrons, where an electron can appear on multiple molecules at the same time. This quantum effect, combined with the Second Law of Thermodynamics, which states that every physical process will lead to an increase in the total entropy, leads to the unexpected energy gain.

“In most cases, a hot object transfers heat to its cold surroundings because the heat transfer leads to an increase in the total entropy,” said Rijal. “But we found for organic molecules arranged in a specific nanoscale structure, the typical direction of the heat flow is reversed for the total entropy to increase. This reversed heat flow allows neutral excitons to gain heat from the environment and dissociates into a pair of positive and negative charges. These free charges can in turn produce electrical current.”

The researchers said the mechanism can be utilized to make more efficient solar cells. They also believe it may be useful when applied to photocatalysts for solar-fuel production, a photochemical process that uses sunlight to convert carbon dioxide into organic fuels.

From pv magazine Global

A U.S. research team has fabricated a mini perovskite solar module based on a special polymer hole transport layer material that reportedly improves the panel stability and efficiency.

“The stability of perovskite modules has not been demonstrated to meet the required 25 years lifetime in many applications,” the research’s corresponding author, Jinsong Huang, told pv magazine, noting that the group was able to build the panel after identifying an ultraviolet (UV) light-induced perovskite degradation mechanism as one of the main causes affecting perovskite module stability.

“We report degradation mechanisms of p-i-n–structured perovskite solar cells under unfiltered sunlight and with LEDs,” the scientists explained, adding that they initially detected the cause of UV light-induced degradation in outdoor testing in the weak chemical bonding between the perovskite layer, the hole-transporting materials (HTM) and the transparent conducting oxide (TCO) layer at the cell level. “This causes perovskite solar cell degradation under sunlight with strong UV components.”

To mitigate the effects of this degradation, the scientists upgraded the perovskite solar cells used for the mini modules with a hybrid HTM based on a combination of EtCz3EPA, a new molecule, and poly[bis(4-phenyl)-(2,4,6-trimethylphenyl)-amine bathocuproine (PTAA:BCP).

This combination purportedly resulted in a stronger interconnection layer at the interface of the perovskite and the substrate in outdoor testing. “We enhanced the bonding at the perovskite/HTM/TCO region via a phosphonic acid group that bonded to the TCO and via a nitrogen group that interacted with lead in perovskites,” the academics explained.

The cells were based on a substrate made of indium tin oxide (ITO), the novel HTM, the perovskite absorber, a buckminsterfullerene (C60) electron transport layer, bathocuproine (BCP), and a copper (Cu) metal contact.

The 15 cm2 perovskite solar module fabricated with this cell configuration was able to achieve a power conversion efficiency of over 16% and retain these efficiency levels for around 29 weeks of outdoor testing. The results were confirmed independently at the U.S. Department of Energy’s Perovskite PV Accelerator for Commercializing Technologies (PACT) accelerator.

“Real-world demonstration is a critical step towards commercialization, and we hope by PACT offering these capabilities researchers and companies can leverage this data toward improved reliability,” the researchers said.

Their work is described in the paper “Strong-bonding hole-transport layers reduce ultraviolet degradation of perovskite solar cells,” published in Science. The research team had members from the University of North Carolina, the Colorado School of Mines, the National Renewable Energy Laboratory (NREL), the University of Toledo, and the University of California San Diego.

“This research is a true collaboration between organic synthetic chemists and solar cell device engineers working together to solve big problems. Furthermore, the chemistry to prepare the molecule of interest in this study is relatively simple and just the tip of the iceberg,” stated Alan Sellinger, a professor at Colorado School of Mines in a press release. Looking at upcoming research projects, Huang said that the group will continue to “understand the degradation mechanisms and find methods to overcome them.”

From pv magazine ESS News site

In what is described as the world’s first, researchers at the Laboratory for Energy Storage and Conversion (LESC) have managed to devise design principles for enabling an anode-free all-solid-state battery.

LESC is a collaboration between the University of Chicago Pritzker School of Molecular Engineering and the University of California San Diego’s Aiiso Yufeng Li Family Department of Chemical and Nano Engineering.

“Although there have been previous sodium, solid-state, and anode-free batteries, no one has been able to successfully combine these three ideas until now,” said UC San Diego PhD candidate Grayson Deysher, the first author of a new paper outlining the team’s work.

To create a sodium battery, which is said to boast an energy density on par with lithium-ion batteries, the research team needed to invent a new sodium battery architecture.

It opted for an anode-free battery design, which removes the anode and stores the ions on electrochemical deposition of alkali metal directly on the current collector. Eliminating the anode enables reduced weight and volume, higher cell voltage, lower cell cost, and increased energy density, but brings its own challenges.

“In any anode-free battery there needs to be good contact between the electrolyte and the current collector,” Deysher said. “This is typically very easy when using a liquid electrolyte, as the liquid can flow everywhere and wet every surface. A solid electrolyte cannot do this.”

However, the liquid electrolytes create a buildup called solid electrolyte interphase while steadily consuming the active materials, reducing the battery’s lifetime.

To continue reading, please visit our new ESS News website.

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Public input sought for large-scale solar project in Arizona  According to the application submitted by developer EDF Renewables, the proposed Socorro project will sit on 3,066 acres on nearly 6,000-acres of public land and it would produce up to 350 MW of solar energy along with battery energy storage.

Yotta Energy launches ‘panel-level storage’ package for C&I solar U.S. storage and inverter specialist Yotta Energy says its new package has several advantages compared to conventional C&I solar storage solutions.

Lithium-ion battery fire safety starts with the manufacturer Fluence America’s president says stakeholder and first responder engagement is necessary to keep failures from becoming newsworthy events.

From pv magazine 6/24

Curtailment is becoming an increasingly important issue for the power sector, particularly as the share of solar and other intermittent-generation renewable energy sources continues to grow.

At small volumes, curtailment rarely poses a major issue for solar plant operators, or for the financial viability of projects. This is mainly because most jurisdictions continue to offer “take-or-pay” contracts that shelter PV project owners, either in part or in full, from revenue losses associated with curtailed electricity output.

In larger volumes, however, curtailment has the potential to undermine the economics of new solar projects, significantly increasing investment risk. Unlike in the past, when solar projects were financed via long-term contracts in the context of auctions or feed-in tariffs, many sites are now being financed either via bilateral power purchase agreements (PPAs) or on a merchant basis, which involves selling energy on the open market. Uncertainty about the volume of electricity that could be curtailed directly increases the cost of capital for PV projects and, in turn, puts upward pressure on the cost of solar. Furthermore, a perception that solar output is being “wasted” could gradually erode public support for further PV deployment, particularly if the curtailed volumes grow substantially.

Deep cuts

Data from a selection of markets show that curtailment is on the rise. In Chile, the curtailment of solar has increased significantly in recent years, affecting 1.4 TWh of output in 2022 – roughly 1.8% of annual electricity demand – and nearly 800 GWh in the first five months of 2023. In Cyprus, PV curtailment has grown from just over 3% of generation in 2022 to more than 13% in 2023. In parts of Australia, curtailment has grown from roughly 4%, in the first quarter of 2022, to more than 7% in the opening three months of 2023, with certain days posting curtailment levels nearing 20% of total available PV output. In parts of the United States, curtailment is also on the rise: in Texas, 9% of the output from utility scale solar was curtailed in 2022. In California, more than 3% was curtailed in the same year. In Germany, the curtailment of solar amounted to almost 2% of total PV output in 2022.

At its core, curtailment is a symptom of an insufficiently flexible power system. Fortunately, experience shows that curtailment can be avoided or significantly reduced through policy. Particularly during the early phases of PV penetration – when up to 10% of power generation comes from solar – there are often other, lower-cost flexibility options available.

At this early stage, the toolkit includes measures such as reducing the must-run hours of fossil-fuel-based power plants; increasing the flexibility of other power generation sources, such as hydropower or biomass; moving toward economic dispatch; introducing intra-day electricity markets; and improving both demand and solar output forecasting.

Broader toolkit

At higher shares of solar generation, a broader toolkit is starting to emerge. Measures include increasing the flexibility and responsiveness of power demand, introducing combined procurement of solar-plus-storage systems, encouraging new business models such as virtual power plants and aggregators, introducing more dynamic electricity pricing, including locational pricing, and making greater use of surplus electricity in the transport and heating and cooling sectors.

Basic economics are also helping as periods of electricity oversupply lead to lower prices, which in turn makes it more attractive to consume electricity. In South Australia, the power system experiences sub-zero electricity prices almost 60% of the time between roughly 11:30 a.m. and 2 p.m. With the continued growth of solar, and without a significant scale-up of demand-side flexibility, markets such as South Australia will start facing repeated periods where daytime electricity prices are permanently negative between 10 a.m. and 4 p.m.

In response, the government and power utilities have started implementing measures to encourage greater flexibility, including through demand-response-enabled pool heaters and air conditioning units, variable electricity pricing, and flexible electric vehicle charging.

Not all negative

From a power system standpoint, curtailment should not be thought of purely in negative terms. It can also contribute to power system flexibility in a manner that can be activated relatively easily to maintain system stability.

In fact, it may be less expensive for solar project operators – as well as for the system as a whole – to curtail PV output occasionally than it would be to build out large-scale energy storage or power grids to ensure that solar output is never curtailed.

With the share of solar rising in virtually every country around the world, it is time for a wider debate about curtailment, how to bind it contractually, and how curtailment itself stacks up both in technical and economic terms against other ways of balancing energy systems. As the world progresses toward its second terawatt of installed solar generation capacity, and beyond, this debate is only going to grow in urgency and importance.

About the authors: Toby Couture is the founder and director of E3 Analytics, an independent renewable energy consultancy in Berlin, Germany. He has 15 years’ experience in the sector and has advised dozens of national and state governments throughout the world on renewable energy policy, strategy, and finance.

David Jacobs is the managing director and founder of International Energy Transition GmbH (IET). He has 20 years’ experience in energy policy design, authoring more than 100 publications. He has advised policymakers in more than 40 countries.