Tag Archive for: Solar

Commodity or Specialty: Tracking Pollinator-Friendly SRECS

“The M-RETS platform—the leading renewable environmental attribute tracking system used by Fortune 25 companies, utilities, and regulators—this year will begin tracking an additional environmental attribute associated with grid-scale solar projects: a pollinator-friendly designation. M-RETS already tracks solar renewable energy credits (called S-RECs) and Minnesota is one of a number of states that have created an official standard and system recognizing solar projects that utilize ground cover that provides meaningful benefits to pollinators, song birds, and game birds.

This additional data gives solar energy buyers the opportunity to encourage the development of pollinator-friendly solar and stack additional environmental benefits on their energy purchase.” – M-RETS

This can be thought of as if your company is buying a commodity product or a specialty product. If these options are the same price, would your company prefer to buy a commodity SREC or a boutique SREC?

Spade Develops Agrivoltaic Software  

“Solar developer and federal grant recipient Sandbox Solar has released a beta version of its agrivoltaic power plant software modeling tool that aids in the design and optimization of solar panels and the crops underneath. 

Sandbox Solar, a solar contractor, has been developing a (software) tool, called Spade. Spade aims to help solar developers determine the best crop types and solar panel layouts for their projects. The tool made it into the fifth and final round of the Department of Energy’s “American Made” solar innovation program.” – PV Magazine 

Spade is a stakeholder in the AgriSolar Clearinghouse. 

Global Agrivoltaics Market Valued at $9.3 Billion 

“Agrivoltaics, the combination of farming practices with energy produced by solar photovoltaics (PV), is forecast to become a $9.3 billion marketplace by 2031, growing at a compound annual growth rate (CAGR) of 10.1% in that timeframe from $3.6 billion a year ago, according to a research note by India-based market research company Allied Analytics.” – PV Magazine 

Solar Could Play Important Role in Cannabis Industry 

“Solar energy and cannabis cultivation are old bedfellows. PV pioneer John Schaeffer has even credited solar with facilitating the northern California cannabis industry, which in turn supported the nascent PV sector. Now, as the legalization of medical and recreational cannabis gathers pace, solar continues to perform a key role.  

Canndescent Senior Director of Compliance Andrew Mochulsky told PV Magazine the Colorado Desert’s unrelenting sunshine and limited cloud cover make solar a no-brainer. ‘We’re in the heart of solar and wind country so it made sense to bring solar online,’ he says. ‘We also think it’s just the right thing to do.’”– PV Magazine 

Sheep grazing at the Mechanicsville site.

By Anna Adair, NCAT Energy Program Assistant

Located near Richmond, Virginia, the Mechanicsville solar park is one of the state’s first utility-scale solar sites. Covering over 220 acres, the 28-megawatt, single-axis tracking site provides a source of clean power to thousands of homes in the state. More than just a solar site, though, the location is also the home base for hundreds of sheep under the care of Eric Bronson and Sam Perkins at James River Grazing. 

James River Grazing started in 2016 when founder Eric Bronson noticed the solar industry beginning to take off in Virginia. A Virginia native, Bronson attended college at Montana State University and worked for several years on large, range-based livestock operations before returning to his home state. He knew he wanted to stay involved in agriculture, but without already owning land, he realized the upfront costs were prohibitive. Compared to raising cattle or growing crops, the lower initial investment needed to successfully farm sheep gave Bronson the chance to farm in a traditional production environment before the company received its first solar grazing contract in 2019.  

For solar sites without grazing plans, mowing must be brought in for vegetation management, a difficult task for many solar developers in recent years due to labor shortages. “The grazing came along at the perfect time,” Bronson says. He explains that the Mechanicsville site was being mowed about once a month, but with the integration of livestock, it was reduced to a “clean up” mow in the fall and smaller mows in early spring. Even then, “they’re not mowing one hundred percent of the site,” Bronson explains. Only about a quarter of the site is mowed at these times, significantly lowering the time and labor cost required to control the vegetation. 

Sheep grazing under the solar panels.

Operating on the Mechanicsville site didn’t come without its challenges, however. The site hosts between 100 and 300 ewes at a time, depending on the time of year and vegetation growth. While smaller operations will move flocks on and off location seasonally, James River Grazing operates on the site year-round. Not having facilities on-site and the expansive costs to move the sheep off-site is an added layer of difficulty that comes with grazing sheep on utility-scale sites. “Everything has to be portable,” Bronson points out. Nonetheless, James River Grazing’s efforts have been so successful that SunEnergy1, the solar developer for the site, hired Bronson as Director of Livestock for the entire company and has implemented solar grazing on a number of other sites, as well. 

With a total of six grazing sites and around 1,500 sheep, Bronson says James River Grazing is looking to continue its success by creating additional partnerships with developers across the region. While being one of the first to embrace solar grazing comes with some advantages, it also means that learning involved a significant amount of trial and error. “That was one of the biggest roadblocks,” Bronson says, referring to the lack of available resources to help guide them in the early days. Their knowledge and experience also put them in an ideal place to help solar developers create construction plans with solar grazing in mind, making it much easier for grazers to care for the sheep on site. James River Grazing is still working out the details for exactly how they plan on moving into the consulting space, but their track record of success will undoubtedly make them a valuable resource for solar developers and new grazers alike.  

All photos courtesy of James River Grazing.

NYPA Study Provides Best Practices for Agrivoltaic Systems

“The New York Power Authority (NYPA) announced the release of a new report, Agrivoltaic Leading Practices, that recommends proven and innovative approaches on integrating dual-land use for agriculture and solar energy production. The study determined that a best practice agrivoltaic site ideally involves stakeholder collaboration, community education, policy incentives, site safety practices, and site-individualized crop selection and solar-array design.

Researchers who authored the new report examined how native vegetation, pollinators, low maintenance plants, agricultural crops as well as grazing livestock can coexist on the same parcel of land as a solar energy project.” – The Mountain Eagle

Research Shows Crops and Solar Panels Benefit from Co-Existence

In the threatening trouble of climate change, growing commercial crops on solar farms is a potentially efficient use of agricultural land that can both increase commercial food production and improve solar panel performance and longevity, according to new Cornell research.

“’We now have, for the first time, a physics-based tool to estimate the costs and benefits of co-locating solar panels and commercial agriculture from the perspective of increased power conversion efficiency and solar-panel longevity,’ said lead author Henry Williams, a doctoral student in Cornell Engineering.” – Cornell Chronicle

New Solar Panels Harness Full Light Spectrum and Increase Crop Yields

“According to a new study from the University of California, the blue part of the light spectrum is the most efficient for solar energy production, while the red part is better for plant growth and crop yield. Now, scientists are investigating how harnessing the sun’s complete light spectrum can improve agrivoltaic system’s effectiveness in arid agricultural areas.” – Horti Daily

This article details Louisiana’s current solar decommissioning regulations and makes suggestions for how to improve the state’s approach to decommissioning solar installations.

Sheep grazing under solar panels.

By Jessica Guarino and Tyler Swanson  

The U.S. agrivoltaics industry continues to grow as the desire to pair solar energy production land uses with pollinator habitats, livestock grazing, and crop production increases. However, while the excitement around agrivoltaics in all its forms blazes a new trail for what solar energy land use can look like, eager landowners and developers face a daunting challenge: state laws and local zoning ordinances that have not considered the possibility that agricultural and solar energy production could feasibly be located on the same tract of land. 

Through Agrivoltaics in Illinois: A Regulatory and Policy Guide, researchers at the University of Illinois Urbana-Champaign’s Bock Agricultural Law & Policy Program analyze both the state and local laws that will impact agrivoltaic development in Illinois. The guide pays particular attention to county zoning ordinances, each of which define solar energy, and set the requirements necessary to develop it, in their own unique way. Agrivoltaics in Illinois allows landowners and potential solar developers to easily understand the requirements to build solar in their county and may also point developers towards counties where solar energy development faces a lower burden from the zoning board. Further, developers can read through the specific definitions that a county has for solar energy, which may have an impact on the development of agrivoltaics. For example, in many counties, a solar farm is the principal use for the land on which it is located, which could have negative implications for a landowner wishing to practice agrivoltaics and retain the tax benefits associated with land being classified as an agricultural use. Meanwhile, other counties state in their zoning ordinances that a solar installation under a specified acreage is considered a “solar garden” and thus is classified as either an accessory or special use of the land. 

Crops growing under solar panels.

Agrivoltaics in Illinois: A Regulatory and Policy Guide, while focused on analyzing the state laws and local zoning ordinances of Illinois, aims to inform all landowners, farmers, and solar energy developers of the types of laws and ordinances that should be taken under consideration when exploring the deployment of an agrivoltaic system. This guide is also a resource for state and local policymakers seeking to understand what impacts existing policies may have on the development of agrivoltaics. For example, the Renewable Energy Facilities Agricultural Impact Mitigation Act is a state law requiring a deconstruction plan for wind and solar energy facilities when they reach their end of life that also provides assurances to the landowners that the land will be restored for agricultural use, which will impact agrivoltaic installations. Additionally, a local official could review the numerous figures and tables in the guide to understand what solar energy requirements are most common, as definitions and requirements for solar energy facilities vary by location.  

As the agrivoltaics industry grows, it will become increasingly important to understand the regulatory framework in which it will exist. Many current zoning ordinances consider solar energy a threat to agriculture and regulate the industry accordingly, which may inhibit the ability of eager farmers and solar developers to deploy the practice. Likewise, state governments have the power to influence the development of agrivoltaics through laws such as the Renewable Energy Facilities Agricultural Impact Mitigation Act. With the legal analysis presented in this policy guide, the authors hope that it will be used by stakeholders to foster informed agrivoltaic regulations and deployment of the practice. 

Photos: AgriSolar Clearinghouse 

Solar panels powering the Solar Oyster Production System (SOPS) platform.

By Anna Adair, NCAT Energy Program Assistant

From filtering water to creating habitats for other marine species, oysters are a vital component of the Chesapeake Bay’s ecosystem. On land, they are the center of a rich cultural heritage as one of the region’s most valuable fisheries. Generations of families have made a living harvesting the bivalves, whose reefs were once so large that they posed navigational hazards for ships traversing the Bay. However, decades of pollution, disease, and overharvesting have devastated the oyster population. Modern restoration efforts and harvesting regulations offer a glimmer of hope for the bivalve, and Solar Oysters is making a big impact with its revolutionary oyster-production platform powered by solar.

Prior to the establishment of Solar Oysters, the idea to create a floating solar array came to Mark Rice, President of the Baltimore-based engineering firm Maritime Applied Physics Corporation (MAPC), while he was working on a project on the Chesapeake Bay. A local power plant utilized Chesapeake Bay water to cool the plant, and there was a growing interest in mitigating thermal discharge into the Bay. Rice and his team decided the best course of action was to remove incident solar energy from the water to offset the thermal effluent. They knew solar panels would generate valuable electrical energy while also helping to keep water temperatures down and began designing floating solar platforms to tackle the problem. As they were planning the floating arrays, they realized a source of ballast was needed to weigh down the systems and found an opportunity to help improve oyster aquaculture in the Bay simultaneously. Led by Steve Pattison, the environmental strategy firm EcoLogix Group collaborated with MAPC to provide valuable insight about stakeholder engagement, local aquaculture, siting, and environmental permitting. The two companies formalized their relationship in 2019 with the launch of Solar Oysters LLC. By October 2021, Solar Oysters had raised enough money through private funding to construct the first Solar Oyster Production System (SOPS) prototype—a floating high-density oyster-production system automated through solar energy—in Baltimore Harbor.

Graphic design of the SOPS prototype.

Measuring 40’ by 25’, the platform has 12 375-watt solar panels attached to the roof capable of generating 36 kWh, alongside four on-board batteries with a 14.4 kWh storage capacity. The solar array powers a system of five vertically rotating ladders on timers, each consisting of 23 rungs capable of holding up to five oyster baskets per rung. This provides a maximum capacity of 575 baskets. As the ladders rotate, the oysters are exposed to different water quality parameters, including temperature, salinity, and dissolved oxygen, resulting in uniformity among all ladder basket positions. At the top of the rotation, the baskets are completely out of the water and exposed to sunlight before resubmerging as the next rung peaks. A manual spray wash system is mounted onboard and pulls water directly from the Bay, allowing those tending the platform to clean the baskets and oysters as needed.

SOPS ladder system
Platform manager Emily Caffrey with an oyster basket from the ladder system.

Compared to traditional oyster farming methods, the SOPS platform brings a technological advancement to an industry that has not changed considerably in decades. On farms where the oysters are grown at surface level in floating cages, workers must manually flip each cage over to prevent biofouling. Biofouling refers to the accumulation of organisms such as algae, barnacles, or mussels on the oyster shells and equipment, thus impeding the growth of the oyster population. SOPS greatly reduces the manual labor needed to keep the oysters healthy, thanks to the rotating ladders and spray system. Moreover, the system’s vertical design drastically increases the number of oysters produced per acre. While a traditional float farm may produce between 250,000 and 400,000 oysters per acre, SOPS can produce up to 250,000 oysters on one 0.02 acre-sized barge. This small footprint is an advantage in securing permits or leases compared to a traditional farm that often requires permitting several acres.

Solar Oysters’ first growing season was in partnership with the Chesapeake Bay Foundation as a participant in the Baltimore Harbor oyster gardening program. A grant from the Abell Foundation afforded Solar Oysters the opportunity to onboard spat-on-shell oysters in the fall of 2021. After the 2022 growing season, about 40,000 oysters were transplanted to the Chesapeake Bay Foundation’s sanctuary reef at Fort Carroll, where they significantly helped to advance the Foundation’s oyster-restoration efforts. That same day, Solar Oysters accepted an additional 490,000 spat-on-shell oysters for the upcoming 2023 growing season. Concurrently, seed oysters were being grown to evaluate the effectiveness of the SOPS technology for the oyster consumption market, onboarded at the same time as the first spat-on-shell cohort. After 12 months of growth, the seed oysters measured between 2.5 and 3 inches in length, a size that could take 18 to 24 months to reach using traditional growing methods.

Seed oysters.
Spat-on-shell oysters.

Solar Oysters’ goal is to develop, manufacture, and sell the SOPS technology to organizations focused on oyster restoration or growing oysters for market. In 2023, they plan to continue research on the SOPS platform as they narrow down the best practices for growing oysters on the prototype. Other improvements to the system will include installing a semi-automated spray wash system that replaces the current manual one onboard. The 2023 season will also see Solar Oysters continue to contribute to restoration efforts in the Chesapeake Bay. With such an encouraging first growing season of both spat-on-shell and seed oysters, the technology has the potential to address environmental concerns while also modernizing oyster aquaculture for growers in the Chesapeake Bay and beyond.

All photos courtesy of Solar Oysters LLC.

This work contributes to agrivoltaic design methodology through a digital replica and genomic optimization framework which simulates light rays in a procedurally generated agrivoltaic system at an hourly timestep for a defined crop, location and growing season to model light absorption by the photovoltaic panels and the crop.

By Asaf Maman and Avi Elkayam, Trigo Solar 

Declining precipitation levels and the associated reduction in arable land can negatively impact rural communities and pose a threat to food security. While utility-scale solar projects reduce greenhouse gas emissions, they can also encroach on arable lands and reduce the yield of rainfed crops. Wheat, barley, soy, corn, and other grains are cultivated in rainfed fields that are vital to food security. As precipitation levels decline and desertification spreads, arable land and farms that produce these crops are in peril.   

As solar energy is employed in the conversion from fossil fuels to renewable energy, hundreds of thousands of square miles of land will include solar development. According to the National Renewable Energy Laboratory, there will be roughly 22,000 square miles of solar in the U.S. by 2035i. It is important to understand that the actual land for solar development must be adjacent to grid or to power demand centers. The growing competition between farming, suburban development, and solar development highlights the potential for agrivoltaics.  

Agri-PV is a solution to this issue. It can significantly improve the cultivation of staple foods that substantially affect global food security by cracking the code and untying the water-land knot. By increasing the amount of water available for rainfed crops, we can increase the amount of arable land and avail a portion of it for sustainable solar development. 

In a series of field-controlled winter wheat experiments, Trigo has discovered an almost linear correlation between the amount of water supplied to cultivated area and the quantity of stem biomass and nutritional value. Based on these findings, Trigo designed an east-west solar array formation and solar table structure to both collect and regulate rainwater for redistribution into a cultivated row below. By increasing the rain capture area from both structures, enclosing, and effectively directing the rain, we managed to control the amount of water and increase it, countering the effects of declining precipitation over years.  

North-south solar array over winter wheat. Photo: Trigo Solar 

Design schematic. Source: Trigo Solar 

This design is focused on economic and efficient deployment of solar arrays that improve rain collection and redistribute water to boost crops growth, counter drought effects, and revive agricultural operations.  

Rainwater catchment design schedmatic. Source: Trigo Solar 

Benefits to this design include:  

  1. Maintaining the same yields from smaller cultivated surface area requires more limited farming operations and lower expenses, which can increase farm profitability. 
  1. Capturing more water and channeling it smartly reduces the risk of drought and the associated annual volatility and provides the farm with a drought shield. 
  1. Increased ground wetness, root growth, and wind shield from the solar rows reduces the erosion and carry away of the upper soil layer, which create irreversible damage to farms. 
  1. Preserved land under the Trigo structure can be used for future land reserve and land rotation. 
  1. The steady income from solar power generation can support farm economics and mitigate farming financial risks. 
  1. The availability of cheap, local, green power can further support many of the farm operations expected to undergo electrification in the coming decade. 
  1. The existence of a water-distribution and cheap-power system changes the economics of farming, potentially allowing the cultivation of second seasonal crop during the dry season.  

These benefits have the potential to create more win-win opportunities for effective cooperation between the agricultural and sustainable energy sectors. 

Trigo will continue its experiments to validate the benefits for major U.S. staple crops at U.S. farms to share the knowledge and promote sustainable mass Agri-PV development.  

By Anna Adair, NCAT Energy Program Assistant

When it comes to conversations surrounding energy and water use in the modern world, the agricultural industry’s consumption of both is often at the forefront. As the world’s population continues to grow, humanity is tasked with the challenge of finding ways to meet both food and energy demands across the globe. “I really believe that greenhouse growing is the epitome of sustainable agriculture,” says Soliculture cofounder and CEO Dr. Glenn Alers. Whether it is the ability to greatly increase crop yields when compared to traditional open field growing, or the potential for increased water-use efficiency in combination with hydroponics, greenhouses could play a key role in addressing these concerns. Solar greenhouses also could also play a role in mitigating future energy crises. 

Soliculture began in 2012 as a startup in the Physics Department at the University of California Santa Cruz. Dr. Alers and his cofounder were conducting research on luminescent solar concentrator panels when he realized the technology’s agricultural potential. Luminescent solar panels utilize a luminescent dye that selectively absorbs a portion of the solar spectrum and readmits light at a different wavelength. The dye used in Soliculture panels absorbs the green portion of sunlight with low photosynthesis efficiency and converts it to red light with much higher photosynthesis efficiency. The panels enhance the light quality inside a greenhouse by optimizing the light spectrum for improved plant growth. Moreover, the panels contain bifacial cells that collect the light reflected from the crops planted below them. The red luminescent dye also enhances the power output of embedded cells by 15 to 32%, compared to a conventional panel. 

Installed Soliculture luminescent solar panels.

In 2019, Soliculture began a research project on Whiskey Hill Farms in Watsonville, California, aimed at developing these solar panels for use on hybrid high-tunnel greenhouses. As an active organic farm already growing produce in both field and greenhouse settings, Whiskey Hill Farms served as an ideal host for the project. The Soliculture research greenhouse was constructed from the ground up with help from a local high tunnel installer, measuring 120’ long and 25’ wide upon completion. Additional bracing was added to the roof structure, forming a “queen style” truss to support the weight of the panels. One half of the high tunnel was covered by a semi-clear plastic film that served as the control for the upcoming crop growth study, and the other was covered by Soliculture solar panels. These panels were specially designed for high tunnel greenhouses and had a cell coverage of 42%.  

Interior of research greenhouse with panels installed.

The project hit a temporary snag when waterproofing the panel racking system proved to be more of a challenge than expected. At first, horizontal mounting bars were attached to the tubing of the greenhouse’s roof frame and foam weather stripping was installed between the panels to create a watertight seal. Water was still able to leak through at the corners and where the mounting bolts connected the panels to the roof. Knowing the potential for these leaks to cause erosion and negatively impact crop growth, the Soliculture team returned to their laboratory and created a modified racking system specifically for high tunnel application. This new system used mounting brackets that attached to the bottom of the frame and utilized a rubber “T” gasket inserted between the panels to create a seal. Finally, the plastic film portion of the roof was attached to the panels using an aluminum channel screwed into the panel frame and “wiggle wire” to hold the plastic film in position. With a waterproof roof in place, the crop trail was ready to commence.  

The following crops were selected for planting following the completion of the high tunnel in mid-November: strawberries, red romaine lettuce, red butter head lettuce, cilantro, mustard greens, and turmeric. To ensure the trial’s results would translate to commercial production, the research team used common commercial growing methods throughout the duration of the trial. These methods included drip irrigation with untreated well water, sand filtration, and liquid organic fertigation. By the end of the trial, the majority of the crops grown under Soliculture panels matured close to two weeks ahead of those grown under the clear film portion of the high tunnel. The fresh weight for the under-panel crops was superior as well, with red butter head lettuce seeing the greatest benefit at 145% higher weight. Mustard greens weighed in at 95% higher, cilantro at 35%, romaine lettuce at 32%, and turmeric at 25%. The strawberry fruit showed no statistically significant difference in fresh weight, but the single 5’ by 120’ planted bed yielded more than 350 pounds of fruit by the end of July.  

Crops grown under Soliculture panels.
Crops grown under plastic film.

On top of the very successful crop trial, the power generated by the greenhouse panels was used by Whiskey Hill Farms to power their day-to-day operations. A total of 58 Soliculture panels provided the farm with a 6kW system, which was connected to an inverter. The AC power was then fed back into the farm’s power system, a testament to how greenhouse solar can benefit the farm beyond improving plant growth.  

The field of agrivoltaics is constantly evolving, with numerous researchers and farmers searching for the ideal nexus between the agricultural industry and energy production. Soliculture’s contributions to agrivoltaics is important for farmers who have reservations about growing food underneath and around solar panels. “We haven’t seen any negative effect on plant growth,” Dr. Alers says, referring to the Whiskey Hill Farms project and several other successful Soliculture installations across the United States and Canada. Greenhouse production has always had the potential to help alleviate the water crisis and increase the amount of food grown per acre, but Soliculture’s technology is giving it a bright future in energy production, as well. 

All photos courtesy of Soliculture 

In this study, a donor:acceptor polymer blend is optimized for its use in laminated devices while matching the optical needs of crops. The study reveals degradation modes undetectable under laboratory conditions such as module delamination, which accounts for 10–20% loss in active area. Among the active layers tested, polymer:fullerene blends are the most stable and position as robust light harvesters in future building-integrated organic photovoltaic systems.