Tag Archive for: AgriSolar

This episode features a conversation between Stacie Peterson, NCAT’s Energy Program Director and Manager of the AgriSolar Clearinghouse, and Lexie Hain, the country’s leading solar grazing expert.  

It is the third in a series of AgriSolar Clearinghouse podcasts that are being featured on ATTRA’S Voices from the Field podcast. 

Lexie is a farmer, solar grazer, and the Director of Agrivoltaics at Lightsource BP.  She co-founded the American Solar Grazing Association and is a stakeholder in the AgriSolar Clearinghouse. She also coined the term solar grazing.  

Lexie and Stacie discuss the practicalities of solar grazing, how to prepare and manage agrivoltaic sites, opportunities for grazers and solar developers, and how sheep and solar are made for each other.


This material is based upon work supported by the U.S. Department of Energy’s Office of Energy Efficiency and Renewable Energy (EERE) under the Solar Energy Technologies Office Award Number DE-EE000937. Legal Disclaimer: The views expressed herein do not necessarily represent the views of the U.S. Department of Energy or the United States Government. 

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Contact Stacie Peterson at stacieb@ncat.org.  

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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. 

Squash 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 

Picture 1. Solar panels powering the Solar Oyster Production System (SOPS) platform.

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.

Picture 2. 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.

Picture 3. SOPS ladder system
Picture 4. 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.

Picture 5. Seed oysters.
Picture 6. 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.

In this study, researchers examined the impacts of animal agrivoltaics on the thermal comfort and wellbeing experienced by dairy heifers, and the potential benefit of offsetting enteric methane emissions. The shade provided by the solar panels efficiently relieved the heat load on the cattle, cooled off their body surface and skin temperatures, and decreased the costs of thermoregulation. Researchers concluded that 4.1 m2 of solar panels would be necessary to offset the methane emitted by the cows.

In this study, a Consequential Life‐Cycle Assessment (CLCA) was conducted to holistically assess the environmental consequences arising from a shift from single‐use agriculture to agrivoltaic systems (AVS) in Germany. The results of the study show that the environmental consequences of the installation of overhead AVS on agricultural land are positive and reduce the impacts in 15 of the 16 analyzed impact categories.

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.

The goal of this policy guide is to summarize both state and local regulations with implications for those wishing to establish agrivoltaic operations in the state of Illinois. The first part of this guide briefly gives a history of agricultural and renewable energy development in Illinois, as well as details agrivoltaic research efforts by the University of Illinois. The guide then covers local-level policies that will have bearing on agrivoltaic development. The final portion of the guide discusses state-level policy that may impact agrivoltaic development, especially in the instance of installing solar panels on agriculturally classified land.

Results of Agrisolar Soybean Pilot Project Revealed by PV Developer 

“French solar developer TSE, in association with Alliance BFC, has unveiled the initial results of a pilot study in France on how solar panels can affect soybean growth. The teams observed solid vegetative growth of the soybeans, with normal flowering, fertilization, and physiological maturation. The six varieties tested presented a diversity of yields: up to 25% difference in yield under the canopy and 19% on the control field.” – PV Magazine 

Oregon Research Studies Use of Vertical PV for Crop Production 

 “There are many different ways to install agrivoltaic arrays. One common method is to raise the array to leave space for farming equipment or livestock to move freely below. Another trending design is to orient the PV arrays vertically, leaving wide open spaces in between the array rows. 

The paper found that an area about the size of Maryland would be needed if agrivoltaics were to meet 20% of U.S. electricity generation. That’s about 13,000 square miles, or 1% of current U.S. farmland. At a global scale, it is estimated that 1% of all farmlands could produce the world’s energy needs if converted to solar PV.” – PV Magazine 

Research Shows Translucent Solar Panels Optimize Crop and Solar Harvest 

“Associate professor Majdi Abou Najm from the Univ. of California, Davis, tested organic solar panels made from translucent material that absorb the blue light to generate electricity, but allow the red light with its longer wavelengths to pass through to the crops below. 

At the UC Davis Agricultural Experiment Station, Abou Najm and his team planted three different plots of processing tomatoes, a common central valley California crop, under a canopy of selective red light, another of selective blue, and a third uncovered plot. 

GNN has reported before on the recent phenomenon of ‘agrivoltaics,’ a practice of growing shade tolerant crops under solar panel arrays. The shade protects the crops from heat stress, while the plants’ transpiration humidifies the air beneath the panels, cooling them down and increasing their electricity output.” – Good News Network 

How current and future research can help us understand the role of pollinator-friendly solar in biodiversity conservation.

In this first episode of the AgriSolar Clearinghouse webinar series, NREL’s Jordan Macknick, James McCall, and Haley Paterson join us to discuss the context and costs of agrivoltaics in the United States.