From pv magazine Global

A group of researchers from the University of Cantabria in Spain has conducted a pilot project for a self-sufficient home that runs exclusively on photovoltaics, batteries, and hydrogen storage.

“This plant combines PV panels and hydrogen (PVHyP) as a method of seasonal energy storage, achieving the ambitious target of accomplishing an electrically self-sufficient social housing unit throughout the year,” the group said. “To achieve this goal, a tailor-made energy management strategy (EMS) has been developed based on the state of charge of the battery pack and the energy flow within the PVHyP, ensuring that the electrical consumption of the home is always covered either through PV panels, fuel cell or battery pack.”

For their simulation, the scientists collected data from January 2022 to December 2023 for an 80 m2 social home that is located in Novales, a small village in northern Spain. Electricity bills from the years before the renewable electrification of the house showed that it consumed 2,513 kWh/year with an average daily consumption of 6.88 kWh. The average consumption in the winter and fall was over 7.3 kWh, and in summer, 5.88 kWh/day.

With these data, the scientists moved to size the energy system using software optimization and market analysis. Finally, they settled on 20 solar panels with a power of 40 W each placed on the roof, as well as four 2.4 kWh batteries. The rest of the plant was installed in a shed in the neighboring plot. That included a 35 L water tank that used tap water after purification for electrolysis and a 600 L hydrogen storage tank at 300 bar.

With the proposed system configuration, the PV panels first must supply the house load. The excess generation will then charge the battery, and once that is full, it is stored in a high-pressure storage tank in the form of hydrogen generated by an electrolyzer.

“When the solar irradiation is insufficient to cover the demand of the house, the batteries supply the necessary energy to the dwelling,” explained the academics. “If the batteries are discharged, the fuel cell generates electricity to charge the batteries from the stored hydrogen. As far as possible, the hydrogen stored in the buffer is used first to avoid the compression stage, thus increasing energy efficiency. The system and the house are connected to the grid on a self-consumption basis to sell back to the grid all the excess energy.”

According to the research group, the house demonstrated self-sufficiency, and its LCOE decreased from €0.86($0.92)/kWh to €0.34 /kWh, and the tenants saved €1,170 annually. “Almost 15,200 kWh have been saved from fossil fuels, which corresponds to approximately 2,260 kg of CO2,” emphasized the researchers.

They presented their findings in the study “Sustainable and self-sufficient social home through a combined PV‑hydrogen pilot,” published in Applied Energy.

From pv magazine global

Energy management company Schneider Electric announced a new Battery Energy Storage System (BESS) for microgrids. It is available in two enclosure sizes and has different storage and discharge configurations.

“Comprised of a battery system, battery management system, power conversion system, and controller, BESS has been tested and validated to work as an integral component of Schneider Electric’s standardized microgrid system, EcoStruxure Microgrid Flex,” the company said in a statement. “It is fully integrated into the software suite, which includes EcoStruxure Microgrid Operation and EcoStruxure Microgrid Advisor.”

The BESS 7 foot long enclosure has a power of 60 kW or 90 kW and maximum storage of 246 kWh, with a discharge configuration of two or four hours. It weighs 3.6 metric tons, and it is AC and DC coupled. On the other hand, the BESS 20 foot long enclosure has a power of 250 kW, 375 kW, or 500 kW, and maximum storage of 1,720 kWh, with a discharge configuration of two or four hours. It weighs 25 metric tons, and it is AC coupled only.

“The BESS is a fully self-contained solution built upon a flexible, scalable, and highly-efficient architecture delivering flexibility, helping to minimize energy costs and maximize renewable energy,” the company added. “As part of a microgrid system, the BESS leverages onsite generation sources to optimize the entire system, delivering energy and cost savings while maximizing usage of renewables.”

Both enclosures use lithium-ion iron phosphate (LFP) batteries, which have a rated calendar life of 15 to 20 years and more than 6,000 cycles. The BESS’s operating temperature ranges from -4 F to 122 F, and Schneider Electric offers a three-year warranty.

From pv magazine Global

A group of researchers from the University of Cantabria in Spain has conducted a pilot project for a self-sufficient home that runs exclusively on photovoltaics, batteries, and hydrogen storage.

“This plant combines PV panels and hydrogen (PVHyP) as a method of seasonal energy storage, achieving the ambitious target of accomplishing an electrically self-sufficient social housing unit throughout the year,” the group said. “To achieve this goal, a tailor-made energy management strategy (EMS) has been developed based on the state of charge of the battery pack and the energy flow within the PVHyP, ensuring that the electrical consumption of the home is always covered either through PV panels, fuel cell or battery pack.”

For their simulation, the scientists collected data from January 2022 to December 2023 for an 80 m2 social home that is located in Novales, a small village in northern Spain. Electricity bills from the years before the renewable electrification of the house showed that it consumed 2,513 kWh/year with an average daily consumption of 6.88 kWh. The average consumption in the winter and fall was over 7.3 kWh, and in summer, 5.88 kWh/day.

With these data, the scientists moved to size the energy system using software optimization and market analysis. Finally, they settled on 20 solar panels with a power of 40 W each placed on the roof, as well as four 2.4 kWh batteries. The rest of the plant was installed in a shed in the neighboring plot. That included a 35 L water tank that used tap water after purification for electrolysis and a 600 L hydrogen storage tank at 300 bar.

With the proposed system configuration, the PV panels first must supply the house load. The excess generation will then charge the battery, and once that is full, it is stored in a high-pressure storage tank in the form of hydrogen generated by an electrolyzer.

“When the solar irradiation is insufficient to cover the demand of the house, the batteries supply the necessary energy to the dwelling,” explained the academics. “If the batteries are discharged, the fuel cell generates electricity to charge the batteries from the stored hydrogen. As far as possible, the hydrogen stored in the buffer is used first to avoid the compression stage, thus increasing energy efficiency. The system and the house are connected to the grid on a self-consumption basis to sell back to the grid all the excess energy.”

According to the research group, the house demonstrated self-sufficiency, and its LCOE was cut by about one-third and the tenants saved $1,251 annually. “Almost 15,200 kWh have been saved from fossil fuels, which corresponds to approximately 2,260 kg of CO2,” emphasized the researchers.

They presented their findings in the study “Sustainable and self-sufficient social home through a combined PV‑hydrogen pilot,” published in Applied Energy.

From pv magazine Global

A global group of scientists led by the Massachusetts Institute of Technology (MIT) developed a novel low-cost solar-powered brackish water desalination system that can reportedly reduce the levelized costs of water (LCOW) compared to conventional PV-driven desalination systems.

The proposed desalination system utilizes time-variant electrodialysis reversal (EDR) technology, which the researchers developed as a flexible variation of traditional EDR desalination. “Our research aims to address water scarcity in rural India where the majority of underground water is too saline to drink. The grid electricity access and stability are not good, suffering from frequent power cuts,” corresponding author, Wei He, told pv magazine.

“An EDR module is made up of a stack of ion exchange membranes and uses an electric field to move ions from the dilute flow channels to the brine flow channels between each membrane,” said the research group. “This electric field can be intermittently reversed to prevent the build-up of scale on the membrane.”

However, due to solar energy’s intermittent nature, the classic EDR is not a perfect fit. It requires constant power for its operation, and therefore, PV-EDR plants need the support of batteries or oversized solar systems, particularly at the start and end of the day when solar power is low.

“To overcome these problems, we have developed a flexible batch EDR technology that incorporates a time-variant voltage and flow rate adjustment,” the academics explained. “A model-based control method enables the EDR system to align its power consumption with available solar power at each time step while optimizing water production under varying solar conditions.”

To control the operation, the team created a feed-forward, model-based main controller running in Python to compute the optimal pump flow rate and the EDR stack voltage based on real-time sensor readings. A prototype was built at a research facility, closely reflecting the typical design parameters and operational conditions for a community-scale PV-EDR system sized to produce 6 m3 freshwater per day. It was powered by a solar panel with an area of 37 m2 and a tilt of 30 degrees.

This pilot system was tested for single-day and six-day analysis and compared to the traditional constant-operation EDR system. Both systems were fed with water with an average starting salinity of 970 mg l−1. The system was set at a conservatively low water recovery ratio of 60%.

“The flexible system is able to directly use 77% of the available solar energy on average compared with only about 40% in the conventional system (a 91% increase),” the scientists emphasized. “This suggests that a conventional system would require much more solar panel area to operate directly (that is, without any energy storage), increasing capital costs.”

In addition, the analysis showed that the average minimum battery capacity required for the flexible system was 0.27 kWh, a 92% reduction compared to 3.3 kWh in the constant system. “Finally, the results show that the flexible system can reach its production volume up to 54% faster than the conventional system,” they added.

Following the experimental results, the researchers conducted a cost analysis case study for the usage of such a system in Chelluru, a rural village in India located near Hyderabad. Using computer simulation and optimization, it was compared to a conventional PV-EDR system, a state-of-the-art constant PV-EDR, and a commercial on-grid reverse osmosis (RO) desalination system. “RO uses pressure to force water through a polymer membrane, while its constitutive ions are blocked by the membrane,” the group said.

“The optimized levelized cost of water (LCOW) achieved by the proposed flexible PV-EDR system is US $1.66 m−3, which improves the cost by 22% compared with the current state-of-the-art PV-EDR system and by 46% compared with the conventional PV-EDR system,” the scientists found. “The LCOW for on-grid RO is US $1.71 m−3, 3% above the LCOW of flexible PV-EDR.”

Their findings were presented in “Flexible batch electrodialysis for low-cost solar-powered brackish water desalination,” published in Nature Water. The team included researchers from King’s College London in the UK, and Helmholtz Institute Erlangen-Nürnberg for Renewable Energy (HI ERN) in Germany.

“For the next step, exploring the long-term performance and broadening the application scope of our PV-EDR technology beyond brackish water desalination presents a significant opportunity to address a wider array of global challenges related to water and liquid waste treatment,” concluded He.

From pv magazine global

Scientists from South Korea’s Korea Aerospace Research Institute (KARI) and the Korea Electrotechnology Research Institute presented in a new paper the advancements of their Korean Space Solar Power Satellite (K-SSPS) project. Namely, they presented a conceptual design of the satellite, its end-of-life disposal method, and a first pilot system and experiment.

“The objective of Japan is to develop gigawatt-level space solar power satellites (SSPS) by 2050, and China aims at megawatt-level SSPS by 2035 and gigawatt-level satellites by 2050,” corresponding author, Joon-Min Choi, told pv magazine. “Although Korea entered the field of SBSP relatively late, it has made notable progress. These advancements exemplify Korea’s commitment to achieving Space-Based Solar Power (SBSP) and contribute to the ongoing collective efforts in this field.”

As for the proposed design of the power-transmitting satellite, the group emphasized that it is “not derived from rigorous analyses but rather serves as system requirements for commercial viability.” Per this design, the system will have a mass of 10,000 tons and transmit microwave at a frequency of 5.8 GHz to Earth via a 1.0 km2 antenna. The microwaves can be converted on the ground to usable electricity via rectennas, which are special receiving antennas that are used for converting electromagnetic energy into direct current (DC).

The system is planned to have two solar array wings of 2.2 km × 2.7 km each. It will use 4,000 sub-solar arrays of 10 m × 270 m, made out of thin film roll-out, with a system power efficiency of 13.5%. On the ground, the researchers propose to place 60 rectennas with a diameter of 4 km along the Korean Demilitarized Zone (DMZ). In that case, 60 satellites will have to correspond to the 60 rectennas.

“If each rectenna could generate 2 GW, the total power collected would be 120 GW, providing approximately 1 TWh of electricity per year,” they said. “This amount exceeds South Korea’s electricity consumption in 2021 (0.5334 TWh) and surpasses the combined electricity consumption of South and North Korea for a certain period of time.”

Based on previous literature, with a lifetime of 30 years, such a structure could provide electricity at a price of  $0.03/kWh. Per the proposal, the satellite bus will first get into the low Earth orbit (LEO), where the main structure and the solar arrays will be installed. After conducting some tests, harvested energy will power the K-SSPS journey from the LEO to the geostationary orbit (GEO).

The disposal method proposed is to intentionally collide the structure at the end of its lifetime into the lunar surface, preferably on the rear side of the Moon. This will ensure the complete removal of its debris from space while also potentially recycling valuable materials for future lunar colony residents.

“As we stand on the verge of commercialization, it becomes imperative to scrutinize and illuminate the inherent weaknesses of SBSP and devise effective solutions or mitigation strategies,” the group said. “Of paramount importance is the necessity to articulate a comprehensive disposal methodology for the mega-size structures associated with SBSP. This substantiation is crucial for justifying the development of SBSP.”

According to the researchers, a pilot system aimed at validating power transmission capabilities and verifying the functionality of deployable/expandable devices can be realized in Korea already in the 2020s. The proposed pilot consists of two small 60 × 60 × 80 cm satellites, each with a mass of 120 kg. One of those will act as an electric power transmitter, while the other satellite serves as a receiver.

“The total solar panel area of the power transmission satellite is not sufficient to continuously transfer the power generated by the Sun, despite the solar panels providing a minimum of 0.39 kW of power,” they said. “To overcome this limitation, the power transmission satellite is equipped with two additional batteries, each weighing 4 kg, allowing for the storage of as much solar energy as possible before transmitting the power to the power reception satellite.”

They also explained the input power of the transmitter will be 8.6 kW, while the output power of the transmitter will be 3.44 kW. They calculated the average output power for different distances, ranging from 100 m to 1,000 m. Per their calculation, for 100 meters, the output load is 162 watts, while for 1,000 meters, it can be as low as 0.12 watts.

In 2019, the KARI set a goal of developing a LEO Space Solar Power Test Satellite by 2040 and a GEO SSPS by 2050. Those goals were also adopted in 2022 by the “KARI Technology Strategy.” The current developments were presented in “Case studies on space solar power in Korea,” published on Space Solar Power and Wireless Transmission.

From pv magazine Global

Soltec, a vertically integrated Spanish PV company, has launched a new 125-meter-long, dual-row horizontal, single-axis solar tracker system. The SFOneX system has a tracking range of 55 degrees, and there is an option to upgrade it to 60 degrees.

“With its self-powered system, equipped with a dedicated panel and a long-lasting battery, the SFOneX guarantees up to four days of autonomous operation without sunlight,” the company said. “Its design with double rows connected by a flexible transmission axis not only reduces the number of tracking motors and controllers by half but also provides a cost-effective solution for solar projects.”

The company said it can be used with 72-cell, 78-cell, or 60-cell modules – both crystalline and thin-film panels. It can adapt to both north-south and east-west orientations of up to 15%. It can use a driven pile, ground screws, or concrete and can handle temperatures of up to 55 C.

“Like all Soltec solar trackers, it features the adapted TeamTrack system that allows maximizing energy capture by avoiding shading between rows,” the company said. “In the case of bifacial tracking, this algorithm also balances production between diffuse and direct radiation to achieve maximum performance. Additionally, the Diffuse Booster algorithm, equipped with advanced sensor systems and weather forecasting, allows for maximizing production even on cloudy days.”

In addition, the tracking system can defend itself from strong wind by adapting to the optimal position. It also has a hail-protection algorithm that uses early detection to protect the PV modules from damage.

“The launch of the SFOneX solar tracker marks a milestone in efficiency and innovation in the solar industry, highlighting its suitability for the US market due to its terrain adaptability, length, self-powered system, as well as its economic efficiency in installation,” said CEO Raúl Morales.

From pv magazine Global

AtmosZero said it has raised $21 million in a Series A funding round. The company said it will use the funds to accelerate the commercialization of its Boiler 2.0 technology.

“Boiler 2.0 can easily be combined with PV power generation and storage,” a company spokesperson told pv magazine. “The tech runs off electricity and it doesn’t matter how that electricity is created, just that it’s there.”

Most industrial steam is generated by burning fossil fuels on-site in boiler systems. It is used in a range of industries, from food and beverage to chemical manufacturing, accounting for about 8% of global energy use.

“AtmosZero’s proprietary Boiler 2.0 technology extracts heat from the air and delivers high-temperature steam with maximum efficiency and zero carbon emissions, allowing companies to replace their existing natural gas and oil boilers quickly and cost-effectively,” the spokesperson said.

The heat pump draws 480 V of voltage in a three-phase configuration and can produce 650 kW of thermal energy, with an output flow of 997.9 kg/hr of saturated steam. Its output temperature-pressure ranges between 120 C/199.8 kPa and 165 C/701.7 kPa.

“The coefficient of performance (COP) of the system is dependent on the ambient temperatures as well as the desired steam temperature,” the spokesperson said. “We work together with customers and perform specific analysis to give them a better insight on expected performance. That being said, our target is a COP of 2 going from 15 C ambient to 150 C saturated steam.”

The system uses an unspecified refrigerant with “low global warming potential (GWP), flammability, and toxicity.” Its footprint is approximately 2.4 meters x 6.1 meters.

AtmosZero is currently testing the system under a full-scale pilot deployed at a facility operated by US-based New Belgium Brewing Company. It also recently launched a European subsidiary.

“Our first systems deploying in 2025 will produce 165 C and in 2026 we will achieve 200 C,” the spokesperson said.

From pv magazine Global

A group of researchers led by the University of North Carolina at Chapel Hill has developed new mini solar modules based on perovskite cells treated with zinc trifluoromethane sulfonate [Zn(OOSCF3)2].

“This low-cost material is used as an additive at a very small percentage into perovskite ink,” the research’s lead author, Jinsong Huang, told pv magazine. “Its use makes perovskite modules cheaper because it makes the fabrication much more reproducible.

Huang also explained that nonuniformity in perovskite films arises from oxidized perovskite inks, especially oxidation of iodide to molecular iodine when inks are exposed to an ambient environment during the fabrication process. In addition, the introduction of 2D-iodide salts in the perovskite inks introduces more iodide interstitials. “Both molecular iodine generation in inks and many iodide interstitials in the perovskite films present nonuniformity in perovskite films and thus lead to larger cell-to-module efficiency,” he added.

The researchers added five different zinc salts into five samples of perovskite ink, and fabricated small solar cells via a blade coating process. The different zinc formations were zinc formate [Zn(OOCH)2], zinc acetate [Zn(OOCCH3)2], zinc trifluoroacetate [Zn(OOCCF3)2], zinc trifluoromethane sulfinate [Zn(OOSCF3)2], and zinc trifluoromethane sulfonate [Zn(OO2SCF3)2]. They also fabricated a reference cell without the addition of zink.

In addition, each cell was tested with different additive concentrations of 0.14%, 0.28%, 0.42%, and 0.55%. On the cell level, the scientists found the Zn(OOSCF3)2 with a concentration of 0.28% to deliver the best results, with an average open circuit voltage of 1.18 V and a fill factor of 82%. This compares with an open-circuit voltage of 1.16 V and a fill factor of 80% in the control cell.

“The results indicate that Zn(OOSCF3)2 improves the device efficiency through defect passivation as both open-circuit voltage and fill factor are significantly enhanced,” said the researchers.

They then used the Zn(OOSCF3)2 at the optimized concentration to blade coat 78 cm2 of perovskite films, from which they fabricated mini modules with an area of 78 cm2, 84 cm2, and 108 cm2, respectively. They all had 20 sub-cells, each with a width of  6.5 mm.

“Fabricated minimodules show power conversion efficiencies of 19.60% and 19.21% with aperture areas of 84 cm2 and 108 cm2, respectively, as certified by National Renewable Energy Laboratory (NREL),” the results showed. “That is the highest efficiency certified for minimodules of these sizes.”

Conducting further investigation into the minimodules’ optoelectronic and morphologic properties, the academics emphasized that Zn(OOSCF3)2 passivated the defects of the perovskites despite its induction of negligible grain size changes. “The CF3SOO‒ anions can reduce the generated iodine during perovskite solution or device aging. At the same time, the zinc cations can precipitate the excess iodide so that the iodide interstitial concentration is diminished throughout the films, resulting in improved device efficiency and stability,” they explained.

The scientists displayed their results in “Iodide manipulation using zinc additives for efficient perovskite solar minimodules,” published in Nature Communications. “To be commercialized, it needs to be applied to equipment that can handle bigger size modules, such as slot-die coater, or roll-to-roll coaters,” Huang concluded.

From pv magazine Global

Researchers from Australia and Vietnam have analyzed the short and long-term dynamics of the so-called solar energy rebound effect.

The rebound effect consists of a reduction in expected gains from a more resource-efficient technology as a result of behavioral or systemic change. As for residential solar, this effect equals the change in a household’s electricity consumption resulting from PV power generation.

“The issue occurs in almost every country, no matter whether it is developed or developing. The issue we found in Vietnam, of which customers abandoned solar systems, is a new finding. However, we believe this could also happen in any country where the policy supporting solar power is not fully and scientifically explained, and where consumers are not comprehensively consulted,” the research’s corresponding author, Luan Nguyen, told pv magazine. 

The research group used a panel dataset encompassing approximately 3500 households in Hanoi, Vietnam, and obtained two datasets on the household and district level, respectively, covering the period 2015-2021. The panel dataset contains detailed monthly information on electricity demand and bills, solar system capacity, production, and installation time. About 48% of the households had PV, and the rest used electricity solely from the grid.

“If households that adopt solar panels also substantially change their energy consumption patterns, it is possible that the overall carbon emissions associated with energy use may be relatively unchanged. This phenomenon is known as a ‘rebound effect,’ where increased supply fails to induce substitution between solar and grid energy,” the scientists explained. “Notably, all homes in the dataset did not possess solar batteries, but none fed solar energy into the national grid. It means all solar owners either consumed all solar production or wasted it.”

To estimate the effects of PV installations on consumption, the researchers used the difference-in-differences identification strategy, which is a statistical method used to calculate the causal impact of an intervention by comparing it to a group that did not receive the same treatment.

“Leveraging a substantial, distinctive, and up-to-date panel dataset, we unveil a substantial rebound effect that challenges the presumed environmental advantages of residential solar energy,” the researchers highlighted. “We are also (to our knowledge), among the first authors to study the dynamics of this process and show that both the primary effect and the rebound effect tend to diminish over time.”

Based on their data, the academics extracted four estimation outputs: two for households’ total electricity consumption and two for demand from the grid. “The only differences between models in each pair are the inclusion or exclusion of exogenous variables, and those differences are to test the consistency of the estimations,” they explained. Exogenous variables included electricity demand, price, income, and other social parameters.

The academics found that, when including exogenous variables, solar installations immediately increased the total electricity demand by approximately 16.3% compared to non-solar households. However, it diminished to about 3.5% after 13 months. Also, the consumption from the grid fell by 3.6% after installation, fading out to about 1.5% at the end of the period.

“Since households that install solar panels may possess unobserved characteristics that distinguish them from households that did not, there is the potential for our results to be affected by unobserved confounding,” they stressed. “However, across a range of diagnostic methods, we find little evidence that endogeneity or misspecification issues may be biasing our results.”

The research group comprised scientists from Australia’s Griffith University, the University of Adelaide, and Vietnam’s Hanoi Power Corporation. Their findings were introduced in the paper “Solar rebound effects: Short and long term dynamics,” published on Renewable Energy.

From pv magazine global

An international research team has developed a novel radiative cooling method for vertical solar panels that uses V-shaped mirrors tailored for the thermal management on both sides of the PV panels.

Radiative cooling occurs when the surface of an object absorbs less radiation from the atmosphere and emits more. As a result, the surface loses heat and a cooling effect can be achieved without the need for power.

“Radiative cooling facilitates the dissipation of heat from a terrestrial body to outer space and the ambient environment through thermal radiation,” the academics explained. “This cooling strategy is particularly suitable for hot PV panels as they can fully utilize the atmospheric transparency window within the 8–13 mm range, and even beyond, due to their operating temperatures being significantly higher than the ambient temperature.”

The novel cooling approach is dubbed v-PV and employs two 45-degree inclined mirrors on the two sides of a PV module. In the front size, an aluminum mirror was used, letting incident sunlight reflect on the module, while the thermal radiation from the front side can be directed to the sky. On the back side of the panel, a spectral selective reflector was installed, enabling the thermal radiation to be directed to the sky while preventing the back of a module from heating up by the scattered sunlight.

To test the proposed method, the scientists conducted three experiments – one in laboratory conditions, another in Buffalo, New York and a third in Thuwal, Saudi Arabia.

In the lab experiment, they used the v-PV with an 18 V polycrystalline module under one sun illumination and in a 1,000 Ω resistor to simulate a realistic operational scenario.

“Double-sided radiative cooling can significantly reduce the operating temperature of a PV module by as much as 51.08 F (10.6 C), leading to an increase in the output voltage by 0.80 V,” they found.

Then, they conducted a field test in New York using the same system configuration. They compared the performance of a cooled module with that of a panel without the spectral selective mirror on the rear side (sv-PV) and that of a horizontal reference panel with no mirrors (h-PV).

“At 12:40, when solar irradiance peaked, v-PV recorded a temperature of 59.6 C, which was still 9 C lower than the h-PV system (68.6 C) and 4.7 C lower than the sv-PV module (64.3 C),” they explained. “These different operating temperatures affected the output. The v-PV achieved a Voc of 18.49 V, surpassing h-PV by 0.59 V (17.9 V) and sv-PV system by 0.20 V (18.29 V).”

The group emphasized that due to its vertical orientation and V-shaped beaming mirror, v-PV receives higher solar irradiance than h-PV at latitudes above 46 degrees. “The v-PV design can achieve significantly higher output in high latitude regions such as Europe and Canada,” they said.

In the Saudi testing field, the researchers tested a modified version of the system. They adjusted the installation angles of the solar panels to 22 degrees and the selective reflectors on the rear side to 0 degrees. The front mirror stayed unchanged at 45 degrees.

The test showed that the surface temperature of the v-PV was 54.5 C, compared to 54.7 C of the h-PV and 55.7 C of the sv-PV. That also translated to improved power, as the different setups reached maximum power of 5.77 W, 4.94 W, and 5.67 W, respectively. Conversion efficiency was 10.53% for v-PV, 10.31% for h-PV, and 10.41% for the s-PV.

“When solar irradiance collection efficiency of the solar panel was enhanced by 15% compared to an aligned, horizontal PV module, the proposed v-PV system maintained a slightly lowered operating temperature of 0.2 C, corresponding to an increase in the maximum power output by 16.8%,” the scientists asserted.

The novel cooling tech was presented in the study “Radiative cooling for vertical solar panels,” published in iScience by academics from Saudi Arabia’s King Abdullah University of Science and Technology (KAUST), as well as the State University of New York at Buffalo and the University of Texas at Dallas in the United States.

Radiative cooling was recently applied to solar panel cooling by researchers from Shanghai Jiao Tong University in China, Purdue University in the United States, the Catalan Institute of Nanoscience and Nanotechnology and the Instituto de Ciencia de Materiales in Spain, and the Jordan University of Science and Technology and the Australian College of Kuwait.

Using remote sensing, researchers from China and the United States have quantified the effects of solar farms (SFs) on albedo, vegetation, and land surface temperature (LST). Namely, they have used data from the MODIS instrument onboard NASA’s Terra and Aqua satellites to analyze data regarding 116 solar farms worldwide.

“Satellite data with high spatial resolution and global coverage enables the detection of changes in surface properties at fine scales,” they explained. “We use long-term remote sensing observations from MODIS, which have good temporal coverage and moderate spatial resolutions.”

While some SFs analyzed in the study were photovoltaic (PV) and some were concentrating solar power (CSP) sites, all had a minimum occupying area of 400 ha. The scientific group also analyzed non-SF buffer areas. They were generated as ring-shaped areas with a width of 1 km surrounding the SF and 1 km away from the boundary.

The research has examined three MODIS measurements – LST, albedo, vegetation, and enhanced vegetation index (EVI). These values were quantified during a 5-year window, as the first measurements were from two years before the year of construction and the last from after two years as well. To rule out any natural climate variability, the change in the buffer area was deducted from the change measured in the SF site.

“Globally, there was a significant decrease in albedo of -0.016 for most SF samples,” the research found. “Regionally, SF in North America (NA) experienced a larger albedo decline (-0.014 to -0.021) than those in East and South Asia (ESA) (-0.010 to -0.017).”

As for the vegetation, the overall EVI index decreased by -0.015, an 8.2% drop. That also exhibited regional variations – as all sites in North America showed a decrease of 0.023 in the EVI, while in East and South Asia, approximately a third of the SF showed an increase.

As for the LST, the researchers found an average cooling effect of -0.49 K during the daytime and -0.21 K during the nighttime. Additionally, 94 of the 116 states experienced land cooling in the daytime, while only 82 experienced it in the nighttime.

“Since there are different types of solar energy technologies, PV and CSP, we searched for pairs of PV and CSP SFs with the same land cover and in the same latitudinal band to compare their impacts,” the researchers added. “On barren land, PV had overall stronger impacts than CSP, except for a larger daytime cooling with CSP. In contrast, on cropland, PV had weaker impacts on albedo and daytime LST than CSP but greater impacts on EVI and night LST.”

The results of their analysis were presented in “A global assessment of the effects of solar farms on albedo, vegetation, and land surface temperature using remote sensing,” published on Solar Energy. It was written by academics from China’s Beijing Normal University, the Southern University of Science and Technology, and the US’s California Institute of Technology.

From pv magazine global

A group of researchers in Europe conducted a study on the impact of solar parks on birds in a Central European agricultural landscape. They surveyed 32 solar park plots and 32 adjacent control plots in Slovakia during a single breeding season.

“We selected ground-mounted photovoltaic power plants with an area of at least 2 hectares,” the researchers explained. “All of the studied solar parks had fixed-tilt solar racks, one of which also had panels mounted on biaxial trackers, and were developed at least eight years earlier. Seventeen solar parks were developed on arable land, and 15 parks were developed on grassland.”

The scientists visited each plot twice, each time surveying it with binoculars for 20 minutes, and recorded all the birds that could be seen or heard. They were then classified according to species, population trends, nesting places, diet, and foraging strata. The plots were also classified for elevation, previous land use, land type, and vegetation management.

Overall, the academic group spotted 353 individuals of 41 species in the solar parks and 271 individuals of 40 species in the control plots. Black redstart, European stonechat, white wagtail, and Eurasian tree sparrow were identified as species most strongly associated with solar parks.

According to the research group, bird species richness, diversity, and invertebrate-eater species richness and abundance were higher in the solar parks than in the control plots. Among the reasons provided by the research group is the food availability for insectivorous birds, as the PV panels attract various species of water-seeking aquatic insects.

“As food availability and accessibility is low in winter, it can be assumed that solar parks can have a positive impact on farmland birds outside the breeding season, as they can serve as stopover, foraging and roosting sites during migration and wintering as the ground under the solar panels can remain snow-free in winter,” the academics explained.

Another possible reason suggested was the higher structural diversity of solar parks.

“We observed that the support structures of the solar panels were used as nesting sites by the black redstart and the white wagtail, the Eurasian tree sparrow nested in the support structures of the panels made of pipes, while the stonechat nested in the uncultivated or extensive vegetation under the solar panels or next to the fence,” the researchers added.

They also stressed that the solar parks considered for the study were designed and managed for renewable electricity production only. “Therefore, it can be assumed that the biodiversity benefits would be even greater if they were managed synergistically with a stronger focus on wildlife,” they concluded.

They presented their analysis in the study “Solar parks can enhance bird diversity in the agricultural landscape,” published in the Journal of Environmental Management. The research was a collaborative work of scientists from Slovakia’s Slovak Academy of Sciences, Gemer-Malohont Museum, Comenius University in Bratislava, Catholic University in Ružomberok, Slovak Ornithological Society/BirdLife Slovakia, and Belgium’s University of Antwerp.

Researchers from the Massachusetts Institute of Technology (MIT) and the University of Virginia are planning to use acenes to develop the so-called singlet fission solar cells.

Acenes are benzene molecules with unique optoelectronic properties. They are polycyclic aromatic hydrocarbons made up of benzene (C6H6) rings which have been linearly fused.

Singlet exciton fission is an effect seen in certain materials whereby a single photon can generate two electron-hole pairs as it is absorbed into a solar cell rather than the usual one. The effect has been observed by scientists as far back as the 1970s and though it has become an important area of research for some of the world’s leading institutes over the past decade; translating the effect into a viable solar cell has proved complex.

Singlet fission solar cells can produce two electrons from one photon, making the cell more efficient. This happens through a quantum mechanical process where one singlet exciton (an electron-hole pair) is split into two triplet excitons. According to the researchers, acenes have the potential to display improved quantum yields in this process.

The research team developed a new synthesis method to stabilize acenes. The new approach consists of adding carbodicarbenes ligands to acenes that are already doped with boron and nitrogen. The scientists explained that acenes doped with these compounds have improved electronic properties. However, they are unstable when exposed to air or light, just like traditional acenes.

“With the addition of the new ligand, the acenes became positively charged, which improved their stability and also gave them unique electronic properties,” they explained.

Until now, most of the boron, nitrogen-doped acenes could emit only blue light. However, with their stabilization, the scientists could produce different colors. Depending on their length and types of chemical groups attached to the carbodicarben, they managed to build molecules that emit red, orange, yellow, green, or blue light.

“We’re still in the very early stages of developing the specific applications, whether it’s organic semiconductors, light-emitting devices, or singlet-fission-based solar cells, but due to their stability, the device fabrication should be much smoother than typical for these kinds of compounds,” the research team stated, noting that red emission, for example, can be used for biological applications like imaging.

Another potential application is to use the compounds as organic light-emitting diodes for screens.

The academics presented their findings in the study “Air- and photo-stable luminescent carbodicarbene-azaboraacenium ions,” published in nature chemistry.

In 2019, an MIT research group demonstrated how singlet exciton fission could be applied to silicon solar cells and could lead to cell efficiencies as high as 35%. They claimed to be the first group to transfer the effect from one of the ‘excitonic’ materials known to exhibit it, in that case tetracene – a hydrocarbon organic semiconductor, into crystalline silicon. They achieved the feat by placing an additional layer just a few atoms thick of hafnium oxynitride between the silicon solar cell and the excitonic tetracene layer.

The MIT researchers described their work as “turbocharging” silicon solar cells and said it differs from the most common approaches to increasing solar cell efficiencies, which these days are focused more on tandem cell concepts. “We’re adding more current into the silicon as opposed to making two cells,” they stated at the time.

From pv magazine global

A group of scientists have tested the use of special solar cells to monitor the behavior of seals during spring migration. They said this is the first long-term deployment of submerged solar cells in a realistic oceanic environment.

“Our work presents the first longitudinal study of photovoltaic cell performance in the marine environment that spans location, time, and depth,” researcher Collin A. Krawczyk told pv magazine. “We highlight novel methods of data collection in the marine environment, using animal hosts as vehicles for water column profile measurements. Based on our power results and energy predictions, solar power could feasibly provide all, or a significant portion, of the daily energy required by many marine wildlife telemetry modules.”

The academics said the electricity requirements of microelectronics applied in marine data loggers and other devices have fallen sharply in recent years, which makes PV a feasible power supply option.

To test their approach, the team attached special monocrystalline mini solar modules to four adult female northern elephant seals. The mammals make an ideal sensor platform for subsurface water profiling, as they average 2.9 dives per hour to depths of more than 400 meters and have migration patterns ranging from southern California to the North Pacific Ocean.

The scientists connected the mini PV panel to a device that measured and recorded the current-voltage relationship, in addition to a SPLASH10 tag that recorded the seal’s location, orientation, temperature, and depth. Unique names were given to each device: Kilo, November, Oscar, and Lima.

“The deployment of these devices began in late February of 2018, and both November and Oscar returned to the initial deployment location in early May of 2018. Kilo performed a much longer deployment, returning in early June of 2018,” the researchers said. “During this extended deployment, Kilo filled its on-board memory. Lima’s results were corrupted by a device malfunction during deployment.”

After recovering the modules, the academics had to perform extensive post-processing on them. They had to calibrate a time lag between the tags and the current–voltage devices and perform a curve fitting process for the latter. They also had to use a method that estimates the short-circuit current of a flat panel based on their tilted observed results. That is the module that was mounted to the head of a diving animal, and their panel-tilt angles were typically non-zero.

They found that maximum power averages as a function of depth are presented at up to 22 meters deep.

“Past 22 meters, our data became reliant on our low irradiance curve estimations, and the data here had very little medium/high irradiance curves,” they said. “At 5 meters depth, results show a 70% to 85% reduction in surface relative power, depending on the tag. While Kilo saw a higher reduction in power than November and Oscar, the reduction in power for November and Oscar at 15 and 20 meters was of roughly 84% and 90% reduction, respectively. At 15 meters, we found that there was an 85% to 95% reduction in available power, which increases to a 90% to 98% reduction at 20 meters.”

The researchers described their experiment in “Trans-oceanic subsurface photovoltaic performance,” which was recently published in Progress in Photovoltaics. They come from Northern Arizona University and the University of California, Santa Cruz.

From pv magazine Global

Researchers at Egypt’s South Valley University have developed a novel control strategy to deal with partial shading in PV systems. The new approach uses a multi-string PV system with a converter control strategy that utilizes a direct duty cycle to track the maximum power point (MPP) under shade.

“This study proposes a reconfiguration of the PV system to suppress the negative impact of partial shading on the PV-system performance by dividing the PV system into multiple parallel strings,” the scientists explained. “In this work, the proposed system comprises four strings, with each string comprising three paralleled sub-strings.”

A global team of researchers has developed a system that harnesses the exhaust grill of an air conditioning (AC) system for the cooling of PV panels as well as drying dishes in a dishwasher.

The method involves the modification of a PV panel into a hybrid photovoltaic-thermal (PVT) module and can be used for both industrial and residential applications.

“This study introduces a novel approach by harnessing the exhaust air from air conditioning (AC) systems to act as a natural coolant, gently flowing over the rear surface of PV panels,” the researcher said. “It eliminates the need for supplementary fans or added power consumption. Its dual functionality not only contributes to a noteworthy reduction in both the carbon footprint, but also yields cost savings on electricity bills.”

The researchers used polycrystalline BP350 panels from UK-based manufacturer BP Solar and modified them so the rear metal contact (RMC) layer was omitted, creating an air channel between the RMC and an added layer of fiberglass. Consequently, the exhausted air from the AC system is directed below the RMC and confined between the RMC and a layer of fiberglass. The air flows from the front of the module to its back.

“The exhausted air from the AC system is utilized to cool the PV panels. This is achieved by directing the air leaving the exhaust grill into a nozzle, which is then connected to the PV panel,” the researchers said. “The air leaving the PV panel becomes hot, presenting an opportunity for its utilization in thermal applications. This hot air is directed to the dishwasher and blown over the wet dishes.”

Using a set of equations and algorithms, the group of scientists calculated the electric efficiency of the cooled PV panel, as well as the efficiency of the recovered thermal energy.

For those calculations, they assumed a residential house with a floor area of 200 m2 in Beirut, Lebanon, and Doha, Qatar, using an AC unit with an air supply temperature of 13 C and maintaining an indoor air temperature of 23 C. The exhaust air entering the nozzle is assumed to have a temperature of 25 C, resulting from heat gain from the ambient air. Using annual average weather data from both cities, the academics have simulated the effect of the novel system on setups ranging from one to ten PV panels.

“Results show that the cooling process substantially enhances the cell efficiency, reaching approximately 10.1% (Doha) to 10.25% (Beirut) for one PV module,” the academics explained. “As the number of PV panels increases, this efficiency decreases but remains higher than the value obtained without cooling. The relative increase in cell electric efficiency ranges from 15% for one PV module to around 3% for ten PV modules.”

Calculating the recovery of the hot air discharged from the back of the PV panel, the researchers found the thermal efficiency reached 98% in Doha and around 80% in Beirut in the case of one PV module. In the case of ten PV panels, that dropped to 55% and 45%, respectively.

“Results show that the time to dry the dishes decreases with increasing numbers of PV from around 7 hours to around 1 hour,” they added. “When the number of PV increases, the air temperature leaving the PV/T system is higher, thus leading to better drying process.”

Concluding the article, the scientists added that future work should encompass real-world testing to validate system performance. Other research, they said, might be regarding “cost reduction efforts, user-friendly integration methods, efficient monitoring and maintenance systems, and collaborative efforts with policymakers to establish incentives and regulations.”

Their findings can be read in the paper “Dual Harnessing of Air Conditioning Exhaust: PV Cooling and Dishwasher Drying,” published in Energy and Built Environment. The team includes researchers from Los Angeles’ Multiphysics Interaction Lab, Lebanon’s American University of Beirut, the Lebanese International University, as well as Kuwait’s Gulf University for Science and Technology.

From pv magazine global

Monoprice has announced a new series of portable batteries. The PowerCache storage systems can be charged via solar panels, wall outlets, and standard 12 V accessory outlets in cars.

“PowerCache Power Stations are UL-certified to meet the industry’s strictest safety standards and feature multiple built-in safety features, including overload and short-circuit protection,” the company said in a statement. “With proper use, the PowerCache 300 Lithium, 600 Lithium, and 1000 Lithium are designed to provide years of safe, reliable operation.”

Colorado-based PV manufacturer Ascent Solar said its proprietary thin-film PV solutions, based on CIGS, have reached an efficiency of 17.55%, up from 15.5% in previous test results.

The company said that current measurements account for a milestone achievement, as 17% is the minimum efficiency required by many satellite companies.

“The latest efficiency increase can be attributed to the addition of rubidium fluoride to the chemistry, combined with improvements to Ascent’s manufacturing process,” the company said in a statement. “The improvements will result in an increase in specific power in the space environment from 1,900 W/kg to 2,100 W/kg at air mass zero.”

Ascent Solar added that it will soon release a new CIGS module with this efficiency. The Titan panel is said to be optimized for use in space environments. First orders are expected to be shipped in the first quarter of 2024.

MIT researchers have developed a new CSP system to produce green hydrogen. The system, which is currently in the conceptual stage, aims to use up to 40% of solar heat for green fuel generation – a significant improvement from previous systems, which only achieved a 7% utilization rate.

“The increase in efficiency could drive down the system’s overall cost, making solar thermochemical hydrogen (STCH) a potentially scalable, affordable option to help decarbonize the transportation industry,” the scientists said. “It is a big step toward realizing solar-made fuels.”

Similar to other STCH designs, the conceptual system can be built around an existing CSP plant, absorbing the receiver’s heat and directing it to split water and produce hydrogen. However, there is a novel two-step thermochemical reaction at the heart of the new system.

“In the first step, water in the form of steam is exposed to a metal. This causes the metal to grab oxygen from steam, leaving hydrogen behind,” the scientists said. “Once hydrogen is separated, the oxidized (or rusted) metal is reheated in a vacuum, which acts to reverse the rusting process and regenerate the metal. With the oxygen removed, the metal can be cooled and exposed to steam again to produce more hydrogen. This process can be repeated hundreds of times.”

The efficiency of this process is related to its train-like design, with box-shaped reactors running on a circular track. Each reactor in the train would house the metal repeatedly going through different thermochemical stations.

“Each reactor would first pass through a hot station, where it would be exposed to the sun’s heat at temperatures of up to 1,500 C. This extreme heat would effectively pull oxygen out of a reactor’s metal,” the group said. “That metal would then be in a ‘reduced’ state – ready to grab oxygen from steam. For this to happen, the reactor would move to a cooler station at temperatures around 1,000 C, where it would be exposed to steam to produce hydrogen.”

Another improvement in the system is its ability to recover most of the heat used in the process. It does so by allowing reactors on opposite sides of the circular train-like track to exchange heat through thermal radiation. In addition, a second set of reactors circle around the first train, moving in the opposite direction and operating in cooler temperatures. This allows the evacuation of oxygen from the hotter inner train, without the need for energy-consuming mechanical pumps.

“When fully implemented, this system would be housed in a little building in the middle of a solar field,” said researcher Aniket Patankar. “Inside the building, there could be one or more trains each having about 50 reactors. And we think this could be a modular system, where you can add reactors to a conveyor belt, to scale up hydrogen production.”

The research team said it will build a prototype of the system in the coming year.

“We’re thinking of hydrogen as the fuel of the future, and there’s a need to generate it cheaply and at scale,” said the study’s lead author, Ahmed Ghoniem.

From pv magazine global

Researchers from space technology company Maxar Technologies have created a new dataset for residential PV system detection by using high-resolution satellite imagery.

“This dataset may be used independently or in conjunction with larger, non-satellite imagery datasets to produce robust detection models capable of generalizing across image types,” the scientists explained. “It may better support the use of satellite imagery in rapidly detecting and monitoring residential-scale solar panel installations, allowing researchers and policy-makers to address the needs of various applications.”

The dataset contains 2,542 solar systems located in southern Germany. The researchers explained that they chose this region due to the high concentration of both residential and commercial solar systems. After acquiring imagery of the area, they randomly chose three areas within the selected region and used software to identify the solar arrays.

They annotated individual solar panel objects manually and, in order to verify their identification, they compared the findings to images from Google Earth, which offers higher resolution images. Objects with potentially only one or two solar modules, either adjoined or separated, were considered as non-panel objects such as skylights, ventilation caps, and chimneys.

“In total, 2,487 solar panel objects, or 97.8%, were identified with high confidence,” the academics stated. “Less than 3.0% of the solar panel objects were identified with moderate or low confidence.”

The scientists said the novel dataset can be either used to develop detection models uniquely applicable to satellite imagery or in conjunction with existing solar panel aerial imagery datasets to support generalized detection models.

The dataset was introduced in the study “A solar panel dataset of very high-resolution satellite imagery to support the Sustainable Development Goals,” published in scientific data.

Maxar Technologies made both the image chips and the object labels available online.

From pv magazine global

A group of scientists led by the University of Guanajuato in Mexico has developed a new methodology to reduce the area needed for the deployment of solar thermal systems installations (STIs) by linking them with heat pumps.

The proposed system consists of a solar collector network, a storage system, and two heat pumps assisted by the solar collectors themselves.

In the paper “Heat and electric power production using heat pumps assisted with solar thermal energy for industrial applications,” published in Energy, the research group, which also includes academics from Texas A & M University in the United States, said that they considered irradiance conditions, the target temperature, and the operation time to design the solar collector network.

“The target temperature of the network is the temperature of the heat pump evaporator, and the target temperature of the heat pump is the process temperature,” they explained, noting that the collector will provide the heat load required by the evaporator, at the evaporation temperature. “The heat pump refrigerant, through isentropic work, will raise the temperature and pressure to supply the heat load at the process target temperature.”

The proposed approach was simulated for a sugar mill that also produces bioethanol and electricity from sugarcane bagasse. The scientists considered two solar-assisted heat pumps to supply the heat and the power of the second generation (2G) bioethanol production process.

For electrical production, the scientists modeled a system that uses thermal energy to heat water, which is then heated by the heap pump evaporator. Then, using R600a as the working fluid of the heat pump, the heat is utilized for an organic Rankine cycle to create electricity.

As for heat production, the system uses thermal energy to heat the evaporator of the heat pump, and the heat produced by the pump is then used in the production process of second-generation bioethanol.

Through their analysis, the researchers found that the heat pumps helped reduce the area needed for the STIs by 85%. “A reduction of 2885 m² was achieved in the absorber area of the solar collector network to produce heat,” they specified. “The reduction in absorber area to produce power was of 586,918 m².”

The simulated system was also able to produce power at a levelized cost of energy (LCOE) of $0.3435/kWh compared with that of fossil fuels estimated at $0.761/kWh. As for heat, the system was able to achieve $0.1257/kWh compared to $0.124/kWh for fossil fuels.

“The process is feasible, because costs to produce process heat are significantly reduced by 20–30% considering the cost of the heat pump; the simple payback time is 6.5–12.3 years,” the US-Mexican group noted.

From pv magazine Global

IEA-PVPS has published a new guidebook to standardize Technological Innovation System (TIS) analysis across different countries for BIPV.

The TIS approach is used to investigate new technological fields and industries in and beyond the context of sustainability transitions. It seeks to understand the dynamics of an innovation ecosystem surrounding d a specific technology and is often used to identify shortcomings and define recommendations for the design of policies in support of a specific technology.

“This Guide for Technological Innovation System (TIS) Analysis BIPV offers hands-on support on theory and methods for those who want to analyze the innovation system for BIPV in their country,” the organization said. “This document can also be used as a template for a final TIS-analysis report – using the same (sub-)chapters, tables, and graphs.”

The handbook presents the rating of the performance of eight functions of the TIS related to BIPV, on a scale of one to five. The functions mentioned are knowledge development, knowledge dissemination, entrepreneurial experimentation, resource mobilization, development of social capital, legitimation, guidance of the search and market formation.

The authors of the report also provided indicators and assessment questions to better produce a well-argued paper. In addition, the report assists the users with setting country-wide targets for the development of BIPV, and also helps them formulate recommendations for overcoming issues, targeting both policymakers and industry actors.

“For those functions that are not fulfilling the target requirements, guidance is given on how to identify systemic problems that either relate to actors, institutions, interaction between actors, or infrastructural deficits,” the report notes.

The report also offers guidance on how to define BIPV correctly, how to analyze historical and technological information, and how to conduct a structural analysis of the specific target country. In addition, it looks at the available technical and knowledge solutions in the relevant market, from early concept development to a fully mature market.

From pv magazine global

An international research group has designed a new mooring system for offshore, coastal floating solar arrays that is claimed to reduce costs of such projects.

Compared to the prevalent method of mooring with elastic cables, the novel method is said to reduce mooring costs for a system of 195 kW by 24%, from $62,200 to $47,160 over its service life. “Elastic mooring cables need to be tightened periodically because the creepage of rubber can lead to the loss of tension resulting in the increase in maintenance cost over time,” the scientists said referring to one of the possible issues in using this technology.

In the paper “An Adaptive Barrier-Mooring System for Coastal Floating Solar Farms,” which was published in Applied Energy, the scientists explained that the cost reduction is due to the cheaper material cost and fewer requirements for maintenance in the new system. “The cost comparison is only indicative as there is significant uncertainty in the various costs,” they emphasized. “In addition, the cost estimations only include the mooring system. Other related costs, such as transportation, have not been considered.”

Dubbed adaptive barrier mooring system (ABMS), the new system consists of perimeter pontoons, barriers, clump weights, mooring lines and anchors.

“The barrier is hinged to the pontoon at the top and tied to the clump weight at the bottom, while the mooring lines connect the clump weight with the anchors fixed at the seabed,” the researchers explained, referring to the functions of the system’s different parts. “The pontoon provides the buoyancy, while the barrier tensioned by the clump weight mitigates the wave action with the mooring lines holding the platform in place.”

In their analysis, the scientists used models scaled at 1:30, with the parameters of the various configurations carefully considered to be realistic compared to field deployment. They compared the performance of a floating array based on a conventional elastic system with that of a floating farm where the sea-facing front is supported by ABMS and the coast-facing rear is supported by a variation of this ABMS-based system where the barrier is replaced by mooring lines.

The researchers found that the system using the new mooing tech is 40% more vertically stable in short wave periods. In addition, the ABMS-based system proved to handle changes in water depth of up to 36%, which is highly relevant under tidal fluctuations, without introducing slack in the mooring cables. “Slack may produce sudden jerks and damage the mooring points,” the researchers explained.

The research team included scientists from the Nanyang Technological University in Singapore and the Dalian University of Technology in China. “We hope that the development of ABMS can further aid the development of coastal floating solar farms in the future,” the team concluded. “At present, floating solar farms have already been installed in freshwater bodies such as lakes and reservoirs. However, very few coastal floating solar farms have been installed so far despite the wider availability in sea space, due to the challenges of more complex environmental conditions in the coastal environment.”