By Savannah Crichton, University of Alaska Fairbanks 

Southcentral Alaska is home to the state’s first agrivoltaics project, a study that aims to uncover the best practices for harvesting from both land and sun. The research team will monitor both farmed crops and native berry plants that grow between the rows of panels at an operational solar PV array.  The solar array is situated in the Matanuska-Susitna Valley, where the majority of Alaska’s farmland is located.  

The project, Agrivoltaics: Unlocking Mid-Market Solar in Rural Northern Climates, is a three-year project funded by the U.S. Department of Energy (DOE) Solar Energy Technologies Office (SETO).  

In 2023, solar developer and project partner Renewable IPP (RIPP) built an 8.5-megawatt solar array in Houston, Alaska, which was financed by diversified clean energy company, CleanCapital. This array is classified as mid-market solar–the middle ground between commercial solar projects and large-scale (>100MW+) utility solar. RIPP sells the electricity produced at this site to Matanuska Electric Association, the regional utility.  

Ribbon cutting at the solar array in Houston, Alaska. 

At northern latitudes, the sun hits the earth at a lower angle, causing solar panels to shade each other during sunrises and sunsets. To maximize energy production and avoid shading, solar developers may increase row spacing. With intentional design and wider rows, there’s ample land open between these rows for foraging or farming. 

The new Houston array is situated on a berry stand well known to local berry pickers. Drawing from their previous solar farm development experience, RIPP intentionally found a way to minimize the environmental impact of solar construction and increase community acceptance by maintaining as much of the native vegetation as possible. Some of the boreal species growing onsite include willow, alder, birch, moss, fireweed, labrador tea, bog blueberry, and lingonberry. The latter two are edible berry species that carry meaningful value to Alaska Native cultures and are prized by many in Alaska’s summer months.  

Instead of aggressive clearing methods that level land and remove certain ecological services, a low-mulching protocol was used to preserve topsoil and low-growing woody shrubs. Native low-growing species, like berries, can continue to grow and sequester carbon. If nutrient-rich soil is left intact, solar developers leave options open for the development of agrivoltaic applications to co-locate their array with food production.  

Blueberry bushes growing on the solar site. 

That’s exactly what a team of researchers at UAF from the Alaska Center for Energy and Power (ACEP) and the Institute of Agriculture, Natural Resources and Extension (IANRE) intend to study. UAF is one of six projects funded under the Foundational Agrivoltaic Research for Megawatt Scale (FARMS) program to conduct research on agrivoltaic opportunity for their communities.  

Principal Investigator Christopher Pike from ACEP and co-investigators Glenna Gannon and Jessie Young-Robertson pulled together an interdisciplinary team of engineers, farmers, and solar experts. The research team is joined by Alaska Pacific University (APU) Spring Creek Farm Manager and project co-investigator Benjamin Swimm,and RIPP founders Jenn Miller and Chris Colbert.  

Under the mission to bolster food and energy security, the team will measure both solar PV production and physiological health of crops over two growing seasons, develop a techno-economic analysis to guide future mid-market solar PV and agriculture projects, and connect with the community through educational programming.  

CEO and Manager of Renewable IPP Jenn Miller speaks to crowd at the solar farm. 

In the first few months of the project, the team compiled a diverse stakeholder pool of northern and Alaska-based landowners, farmers, utilities, solar developers, tribal organizations, academic researchers, and environmental agencies. Through individual outreach, team networks, and local events, over 200 people signed up to participate in a stakeholder needs assessment survey.  

The survey was distributed to evaluate stakeholder perspectives towards agrivoltaics in rural northern contexts. In addition to this data, the team will conduct a techno-economic analysis to understand the economic conditions in Alaska that may create hurdles or opportunities for those interested in developing agrivoltaic systems.  

The contributions from the stakeholder survey and follow-up interviews will inform the project’s agricultural research plans and economic analysis. Broadly, this input helps the team understand community acceptance and potential adoption of multi-use solar farms while also adding color to the picture of food and energy security in rural, northern regions.  

Preparation of the agricultural research plots at the Houston array will begin in summer 2024. The acidic silt loam soil will be amended with lime and compost in plot locations to make them more amenable to agricultural growth.  

With the soils tilled, planting will begin in summer 2025. A combination of popular commercial vegetables and animal forage crops will be planted and monitored throughout the growing season for their productivity both inside and outside the solar array.  

Crops at northern latitudes undergo unique challenges, like cool growing seasons and high solar radiation loads. Because of these unique conditions, some crops grown under solar PV arrays may experience improved productivity, while other crops that are usually productive in the rural north may not perform as well.  

Gannon, Young-Robertson, and ACEP research professional Savannah Crichton will coordinate the collection of plant physiology data of the agricultural crops, as well as the existing blueberry and lingonberry plants. Leaf-level physiological measurements of photosynthesis, transpiration, water use, and stress help define the dimensions of health in plants. These measurements will allow the team to understand the impact that fixed solar modules and increased shade have on the plants’ overall health, crop yield, and produce quality.

Close-up of the blueberries growing on-site.

Likewise, Pike and ACEP research engineer Henry Toal will monitor the solar power production and gauge the impact of farming activities on the array’s operation and maintenance costs. Weaving together qualitative, economic, physiological, and electrical data will allow the team to evaluate the feasibility of agrivoltaic systems in the north.  

Rural households in Alaska spend nearly 27% of their annual income on energy expenses, and around 95% of Alaska’s non-subsistence food supply is imported. If an agrivoltaic model works in Alaska, it could be a major breakthrough for increasing food and energy security in the state. The impacts of this research have significant potential value, not just for solar developers and farmers, but for entire communities.  

If you’d like to learn more about the project, visit our website or email Savannah at sgcrichton@alaska.edu.  

The research 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 (SETO) Award # DE-EE0010442. 

Cantaloupe melons growing between rows of solar panels. 

By Anna Adair, NCAT Energy Program Assistant   

Just south of Portland, Oregon, researchers with Oregon State University (OSU) are putting agrisolar principles to the test at the Oregon Agrivoltaic Research Facility. The site is located at the Noth Willamette Research and Extension Center (NWREC) and serves as host to OSU’s ongoing agrivoltaic research under the leadership of Dr. Chad Higgins. The numerous studies conducted on the site will contribute to advancements in multiple fields, including plant physiology, water usage, and soil health, all while producing power for Oregon citizens through a community solar program.  

While agrivoltaics research has picked up in recent years, a large number of the sites being studied were not originally built with agrisolar pursuits in mind. Although it’s entirely possible to successfully integrate agricultural practices into an existing solar array, using only these sites for research lessens the opportunity to discover agrivoltaic’s full potential. With the Oregon Agrivoltaic Research Facility, Dr. Higgins and OSU flipped the narrative by instead asking: what if a solar site was designed to maximize agricultural production?  

The OSU team felt it was important to approach the project from the perspective of a farmer looking to add panels into their current operations. With that goal in mind, the decision was made to design an array that wouldn’t necessitate the purchase of specialized farming equipment capable of working amongst the panels. Instead, they used NWREC’s current tractor to determine how far apart the bifacial panels needed to be spaced and chose a racking system that can tilt to a vertical position on command.  

A row of dry farmed crops between solar panels. 

Once again approaching the project as a farmer might, Dr. Higgins and his team chose to fund the project through loans, investors, and grants rather than having the university entirely foot the bill. The team partnered with Oregon Clean Power Cooperative (OCPC), who financed the project and maintain ownership over the site. OSU contributed about 5% of the necessary funds, and OCPC’s community investment model provided the framework for local investors to contribute as well. The project also received grants from both Portland General Electric and the Roundhouse Foundation, which provided funding for on-site NWREC staff, research, materials, and construction costs. OSU anticipates the project will pay for itself in about 10 years.  

In addition to providing space for agrisolar research, the site also serves as a community solar operation with Oregon Clean Power Cooperative. OCPC was heavily involved in the project from the beginning, working with Dr. Higgins to design the system and purchase the equipment in the midst of a supply chain crisis during the pandemic. Thanks to the dedication of both parties, construction on the 5-acre, 320-kW site wrapped up in the fall of 2022, and it began producing power the following April. The site is OCPC’s first community solar project for Portland General Electric customers. Currently, OSU buys some of the power from the array, and the remaining is purchased by a local church, synagogue, and area residents, including low-income households who receive the power at a 50% discount. The partnership between OCPC and OSU has been so successful that OCPC is in the process of developing two more sites for OSU’s agrivoltaic research in the state.

Melon crop area being monitored for detailed data collection. 

Although the Oregon Agrivoltaic Research Facility is only in its first year of operation, extensive studies are already underway onsite. By the end of fall 2023, a study on soil compaction from installation will be complete, as well as an investigation into soil health in bare ground versus agrivoltaic spaces. OSU is also investing in long-term research, with a 20-year study on pollinators beginning in fall 2023. More extensive soil-quality projects will also start in the fall, looking to determine how an agrisolar system impacts soil health markers over 20 or more years. Sheep will graze on the site for part of the year, allowing for research on seasonal forage and sheep nutrition.  

Dr. Chad Higgins and Follow the Sun tour attendees behind Argonne National Lab’s wildlife monitoring camera. 

Nestled in the center of the array is a grassy row with a camera set at one end, seemingly at odds with the rows of plants surrounding it. This unassuming row is actually the location of two important studies, one focused on wildlife and the other on grass growth as a proxy for crop productivity. Argonne National Laboratory monitors the camera for wildlife that wander into the array, concentrating specifically on observing how the bird population interacts with the solar array. The grass is just one of several plots around the world included in an ongoing study by the United Nations, which is dedicated to predicting how certain crops will grow in a given environment. NWREC is home to another one of these plots, located outside of the array, and OSU team will analyze how the two onsite plots compare. This will give them insight into how a number of crops are likely to grow within the array without having to actually cultivate each plant.  

In September 2023, the AgriSolar Clearinghouse’s Follow the Sun tour had the opportunity to join Dr. Higgins in Oregon and see the OSU team’s crop research in action. The researchers chose to grow their crops using a technique called “dry farming,” which relies on soil moisture and rainfall to water the plants rather than irrigation. Agrivoltaics pairs particularly well with dry farming because the shade from the solar panels significantly reduces soil moisture loss. Several varieties of squash, tomatoes, melons, hemp, and hydrangeas were successfully growing between the panels, and plans to add blueberries in the coming months were on the docket, as well. More than 75 people signed up to attend the tour and had the opportunity to listen to Dr. Higgins discuss the research facility, scalability of the project, financial considerations, and initial observations of the plants growing within the array.  

The Oregon Agrivoltaic Research Facility’s commitment to embracing dual-use agriculture is truly inspiring. In addition to the research already in progress, there is an entire row of panels dedicated to experiential learning, the development of lesson plans, and opportunities for students. OSU’s clear investment in both current and future leaders in the agrisolar world leaves little doubt that the site will become a major contributor to the ever-growing body of agrivoltaic knowledge. 

Hemp plants (left) and delicata squash (right) growing within the array. 

Photo credit: NCAT

A

Vines growing among solar arrays. Photo: NCAT

By Brian Naughton, Co-Founder Circle Two, LLC. This article was first published in the NM Healthy Soil blog.

The sun provides abundant energy here in New Mexico, something I’ve appreciated professionally and personally since moving here ten years ago to work on renewable energy. The sun can also be a bit much at times as seen in my rather disappointing tomato patch this year. I’ve always enjoyed gardening as a hobby, but a few years ago I decided to step things up a bit by volunteering at the Rio Grande Community Farm located on the Los Poblanos Open Space in the North Valley of Albuquerque. I’ve learned so much from the community that gathers and works there about every aspect of growing food from soil health, irrigation methods, tools from small to big, and climate-controlled greenhouses to the changing climate of the open field.

One of my first days volunteering at the farm I noticed a stack of solar panels in the barn and began to brainstorm ways my renewable energy background and interest in growing food might work together. In the course of my research I came across the term agrisolar. Agrisolar, or agrivoltaics as it is sometimes called, is simply the co-location of solar power production with appropriate agricultural land use. This definition comes from the National Center for Appropriate Technology (NCAT), hosts of the AgriSolar Clearinghouse, a website for all stakeholders who are interested in finding trusted agrisolar information, funding sources, events, and more. 

As I’ve learned, there are multiple potential benefits of pairing solar and agriculture. As interest in both renewable energy and sustainable agriculture grows, agrisolar has the potential to meet both needs. The benefits include producing food, conserving ecosystems, creating renewable energy, increasing pollinator habitat, and maximizing farm revenue. In our arid Southwest landscape, researchers at the University of Arizona have found the microenvironment among the solar panels can increase humidity, decrease daytime temperatures, and increase nighttime temperatures, all of which can increase the efficiency of crop production and solar electricity generation in a symbiotic relationship.

Tomatoes growing in an agrivoltaic setting. Photo: NCAT

I find the broader connections between energy and food quite interesting and important. Sunlight is the primary energy source that keeps our living ecosystem, and our human gizmos, moving. Plants absorb the daily flows of sunlight to convert carbon dioxide in the air into biomass above and below ground. Our human systems largely do the opposite, combusting stocks of solar energy in the form of fossil fuels in the ground and turning them into carbon dioxide in the air, with all the resulting impacts we’ve come to know too well. Our domesticated crops turn out, perhaps unsurprisingly, to be a bit of a mix of energy sources.

Researchers at the University of Michigan have compiled data from multiple sources to produce some eye-opening infographics on energy use in the US food system. The biggest takeaway for me is that on average it requires 14 times the energy inputs for each calorie we consume, and the majority of that input is still fossil fuels. Perhaps agrisolar projects can help shift that statistic towards something more sustainable, but there are some knowledge gaps about how best to deploy this technology.

Agrisolar in New Mexico

One of the six soil health principles promoted by New Mexico Healthy Soil and others is to know your context. This applies equally well to agrisolar projects and the need for location-specific knowledge. While some agrisolar knowledge and practice is universal, much of it is location-specific. Fortunately, there are a few nascent efforts in New Mexico beginning to explore agrisolar applications and develop best practices for our state. I’ve chosen a few to highlight that I’m aware of, but I’m sure there are many more people and organizations that are experimenting with this approach that I have not yet learned of. 

New Mexico State University

Researchers at New Mexico State University just completed their first year investigating New Mexico green chile production under partial agrivoltaics shading at the Leyendecker Plant Science Research Center near Las Cruces. Drs. Marisa Thompson, Stephanie Walker, Olga Lavrova, and Israel Joukhadar lead the project that is supported by the New Mexico Department of Agriculture’s Specialty Crop Block Grant program. Mariela Estrada is a graduate student on the project helping to coordinate the field trial and gather data, which is currently being analyzed. The project is exploring the effects of integrating solar panels into vegetable production fields, with a particular focus on the impact on disease, plant growth, and overall yield. This innovative integration of technology into agricultural fields has the potential to offer dual benefit to New Mexico producers, protecting their crops from the region’s hot and arid climate while simultaneously generating additional income through renewable energy production. The researchers are considering additional crops they could study in the coming years.

Chiles growing on an agrisolar research site at New Mexico State University. Photo: Israel Joukhadar

USDA Agricultural Research Service

Another agrivoltaics research project in the Las Cruces area is being led by the USDA’s Agricultural Research Service. Brandon Bestelmeyer from the Range Management Research location and Derek Whitelock from the Southwest Cotton Ginning Research Laboratory are collaborating on a project titled “Sustainable Multi-functional Agricultural and Energy Systems for Arid Environments.” The project aims to develop optimized agrivoltaic designs for rangeland, crops, and processing facilities and to build accompanying decision support tools including economic and life-cycle assessments so farmers and ranchers can make informed decisions about their operations. The project will be a highly collaborative effort engaging with multiple stakeholders. University partners will support experiments in photovoltaic installations exploring crop and soil types common to Southwestern ecosystems at agricultural research centers and postharvest processors. Government agencies and agricultural stakeholders managing land on which renewable energy is being developed are also envisioned as project partners. The project just kicked off in 2023 and will begin by defining knowledge gaps about potential agrivoltaic co-benefits and challenges to determine priorities for subsequent research in the region.

Los Alamos National Laboratory

One of the first agrivoltaics projects I learned about was in the El Rito area led by Los Alamos National Laboratory researcher Sanna Sevanto to support Trollworks, a biochar production equipment manufacturer located in Santa Clara, NM. Funded through the New Mexico Small Business Assistance Program, the researchers tested the effects of biochar on plant growth in an agrivoltaics setting at the solar installation located at Northern New Mexico College’s El Rito campus. Growth and productivity of tomato and Swiss chard was compared on plots where originally non-arable soil was amended to crop growth by incorporating compost and a compost-biochar mixture to the original soil under and next to the solar panels (see photo). The 1.5-megawatt solar installation itself was constructed in 2019 under a partnership between Northern New Mexico College, Kit Carson Electric Cooperative (KCEC), and Guzman Energy. The array helps to transition not only the college, but also the entire KCEC membership and communities west of the Rio Grande served by KCEC toward achieving 100% daytime solar power.

SunShare

Community solar offers a particularly exciting opportunity for agrivoltaics in New Mexico. Signed into law in 2021, the program administrator awarded the first 200 megawatts of capacity to multiple solar developers to construct projects up to 5 megawatts each that will offer subscriptions to customers of the three investor-owned utilities in the state. One of those developers is SunShare, a developer of community solar installations founded in 2011. In addition to providing workforce development opportunities, lease payments to local landowners, and electric bill discounts to low-income subscribers, SunShare will be working with New Mexico Healthy Soil Working Group to incorporate agrivoltaic design concepts into their New Mexico projects. SunShare already has some demonstrated experience with agrisolar on a project in Minnesota working with local farmers on vegetable production and an apiary located within the solar panel rows (see Minnesota Farm Guide: Agrivoltaics—Solar plus farm production is gaining ground).

Sandia National Laboratories

The final agrivoltaics project I’d like to highlight is from a diverse team led by Dr. Ken Armijo at Sandia National Laboratories with partners at SkySun, University of New Mexico, Jemez Mountain Electric Cooperative, Rio Grande Community Farm, and my own company, Circle Two. The project started this fall and will explore a novel solar technology developed by Skysun and Sandia over the next two years including laboratory testing at Sandia, field testing at Rio Grande Community Farm and assessing the commercial potential within the Jemez Mountain Electric Cooperative service area. The unique design of the photovoltaic system (see image) will allow improved crop cultivation access with tractors and personnel along with more efficient operations and maintenance over commercially available fixed-framed agrivoltaics installations. The agrivoltaics system will be connected to a battery storage and control system forming a microgrid to power on-site loads including an electric tractor and irrigation pumps. This project brings my agrivoltaics journey full circle starting with that stack of solar panels in the barn and now exploring the potential benefits of combining solar energy and crops in the field at the nearby fields at Rio Grande Community Farm.

Click here to view the original post and photos on the New Mexico Healthy Soil blog.

P

Chile plants within shade of photovoltaic panels (right) and chile plants cultivated in full sun (left). 

Written for the AgriSolar Clearinghouse by Israel Joukhadar and Stephanie Walker, New Mexico State University  

New Mexico has tremendous potential in solar energy production thanks to its consistently sunny weather and high levels of solar irradiance. Presently, the state’s solar market holds a value of $3.2 billion with significant room for expansion. As stakeholders express increasing interest, they are discovering a trend observed in several other states: some of the most favorable locations for extensive solar developments are within agricultural production fields. The concept of integrating photovoltaic (PV) panels into these fields, known as agrivoltaics, has gathered attention and investment. 

Chile (Capsicum annuum L.) holds significant importance as a vegetable crop in New Mexico. Chile was initially brought to New Mexico more than 400 years ago and it has been continuously cultivated throughout the state since that time. Its cultivation and trade hold immense cultural importance to New Mexico, while simultaneously contributing to the state’s economy by providing income and employment to farmers and through supporting industries. Producers in the state harvest both red and green crops. Green fruit are full size, but physiologically immature, while red fruit are physiologically mature. The question of “Red or Green?” is the official state question, symbolizing the preference for either red or green chile and showcasing cultural attachment to this beloved crop.    

New Mexico State University is home to the longest running chile pepper breeding and genetics program in the world. This initiative traces its roots back to 1888, when it was initiated at the New Mexico College of Agricultural and Mechanic Arts, the precursor to NMSU, under the guidance of Fabián García, the first director of the Agriculture Experiment Station. Dr. García embarked on a journey of breeding and selection that eventually led to the development of New Mexico pod-type chile, which is now globally recognized as New Mexico type (NM) or Hatch chile. Over the course of its existence, the NMSU chile breeding program has introduced more than 50 distinct chile varieties.   

New Mexico is the largest chile producer in the US; however, since peak production in the early 1990s, there has been a reduction in acreage. The decline was the result of various factors including labor shortages, increased international competition, and heightened disease pressure. Increasingly, heat stress and irrigation availability are adversely impacting the crop. To protect and sustain NM chile production, it is imperative to implement a multifaceted approach to address various challenges encountered by producers throughout the production and post-harvest processes. More than a decade ago, research scientists at NMSU initiated efforts to develop mechanized harvesting solutions, aiming to alleviate the challenges posed by labor shortages. Now, those very research scientists are joining the agrivoltaics research movement. Their goal is to address additional challenges faced by NM chile producers. They are exploring co-location of PV panels within agricultural fields as a potential strategy to address certain challenges. Thanks to a grant from the New Mexico Department of Agriculture awarded to Drs. Thompson, Walker, and Lavrova, research has begun in evaluating how solar panel shading affects the movement of beet leafhoppers. These leafhoppers are vectors for the Beet Curly Top Virus (BCTV), a significant disease impacting the state’s signature chile pepper crops.  

Infection with BCTV results in various symptoms including stunted growth, curling and twisting of leaves, and the production of small unmarketable fruit. The specific symptoms may vary based on the plant’s growth stage when it becomes infected. Previous research has shown that beet leafhoppers tend to avoid shaded areas and exhibit peak activity between 10 am and 2 pm. The concept was to leverage the shade provided by solar panels as a means of deterring beet leafhoppers with the goal of reducing the incidence rate of the BCTV while not adversely impacting yields of chile peppers grown under the PV panels. This research was conducted at NMSU’s Leyendecker Plant Science Research Center, located near Las Cruces, NM. Before the first season, four fixed PV panels were installed, adhering to low-impact installation guidelines to minimize land disturbance. The panels were facing east. Although this is not the most efficient orientation for energy generation, it was ideal to shade the chile between 10 am to 2 pm. Then ‘NuMex Odyssey,’ a green chile variety developed for mechanical harvest, was transplanted into the field in the beginning of May and harvested in mid-August 2023. After completing the initial field season, many valuable insights were gained that will be useful for interested NM stakeholders. Preliminary results indicate potential yield and BCTV prevention benefits to chile plants cultivated under the shade of PV panels, but a second year of data is necessary to draw more specific conclusions. 

Romaine lettuce harvested from partially shaded area under photovoltaic panels

Danise Coon, Mariela Estrada, Isaac Medrano, and Jannatul Afroze (left to right), measuring harvested lettuce. 

Traditionally, chile is cultivated within a crop rotation strategy to mitigate soil-borne diseases. To mimic this rotation cycle, romaine lettuce (Lactuca sativa) was planted immediately after the chile crop in the beginning of September and harvested by the end of October 2023. During this transition, the orientation of the solar panels was modified from an east-facing direction to a south-facing one. The shift in panel orientation served two primary purposes: 1) During the chile growing season, shading between 10 am and 2 pm was essential to deter beetleaf hoppers. As the crop changed to romaine lettuce, this shade was no longer necessary and 2) With the advent of cooler mornings in September and October, increasing the morning sunlight became imperative to warm the plants effectively. This transition prompted a crucial consideration in the fundamental objective of each agrivoltaics site. Should it aim to maximize energy generation or crop production?  

Our present objectives include conducting a repeat of both these studies next year and sharing research outcomes with the public. Alongside our ongoing research, we are actively pursuing funding to broaden our investigations. This expansion will encompass flavor and nutrient analysis of the crops, various vegetable types and varieties, optimal irrigation designs, as well as further explorations into pest and diseases with agrivoltaic systems in New Mexico.  

Photos courtesy of Israel Joukhadar. 

As we strive for climate change solutions, competition over land for food production or clean energy production is an emerging challenge to address this challenge, demonstrations of systems that produce energy and food on the same land are needed to usher in solution-scale adoption of these practices. A new research project at the University of Delaware (UD) will study the results of growing food crops underneath uniquely designed PV solar arrays. SolAgra Corporation will oversee the installation of two solar arrays at the UD Newark and Georgetown campuses. Once built, these sites will have the potential to demonstrate just how symbiotic solar energy and agricultural production can be. 

Professors Steven Hegedus, UD Department of Electrical and Computer Engineering, Gordon Johnson of the Plant and Soil Sciences Department, and Emmalea Ernest, Agriculture Program Leader, will work with their students to investigate the potential benefits to food crops grown beneath the PV arrays. All the preliminary engineering studies for the project are completed and approved, and construction is on track to be completed by the start of the growing season in April 2024. UD will fund the installation of the solar arrays and the initial crop plantings underneath. Further funding from the US Department of Agriculture and the US Department of Energy is being pursued to sustain a multiyear study of the sites. 

Barry Sgarrella, founder and CEO of SolAgra, said he developed the raised solar platform that will be used in the UD project to “help farm families be more profitable and to slow the trend of farmland being consumed by commercial development.” The SolAgra Farming Array™ will consist of elevated array segments with 15.5 feet of clearance to accommodate the tallest agricultural equipment. The racking will be assembled and the solar panels installed at ground level and then hinged into an upright position. 

 The panels will track the sun to increase energy production by as much as 15% and, when needed, they can be rotated so the panel edge is perpendicular to the sun to allow the maximum amount of sunlight to hit the crops below, a function Sgarrella calls CounterTracking™. This, coupled with the unique ability to shift the entire array east or west, called DynamicShifting™, will deliver varying degrees of sunlight or shade to crops planted below as needed. The rows of solar modules will be installed on 11.25-foot centers, a relatively dense panel row spacing for agrisolar cropping applications.  

Dynamic Shifting allows the entire array to move side to side for the least amount of shading possible.

Each array segment will be 35 by 45 feet and is designed to hold enough solar panels to produce 17 kW of electricity. The array segments will be modular and can be scaled up to much larger size arrays. Each research site at the UD project will contain two array segments totaling 68 kW of installed solar panels. The two systems will be identical except that the array installed on the Newark campus will house bifacial solar panels to study how much electric production can be gained from light reflecting off the crops and ground back to the underside of the panels. Sgarrella stated that the cost to install a segment is comparable to other raised-platform solar arrays of the same size, and costs would decrease for larger installations as economy of scale is achieved.  

According to Professor Hegedus, part of the research will involve looking at crop production at different shading levels. Photo saturation is the point at which plants cannot efficiently utilize more sunlight in the photosynthesis process and once the crops are at that point, it makes sense to utilize the light for energy production. The crops that will be included in this study are strawberries, tomatoes, peppers, and lettuce and were chosen because of their high market value. The flexibility of the SolAgra Farming Array™ design will allow the researchers, through controls on their smart phone or tablet, to provide full sun, full shade, or anything in between based on individual crop needs. The results can then be used to help develop shading schedule algorithms that can control the system for different crops. 

Sensors will be used to measure direct and diffuse illumination under the panels, soil and air temperatures, humidity, and crop temperatures to start quantifying crop benefits. It’s expected that the soil in the shade of the panels will retain moisture and that the crops will require less irrigation, which has been shown as a benefit of agrivoltaic cropping systems in other research.  

The researchers will also orient the panels horizontally to test the system’s ability to protect crops from severe weather like rain or hale. Even in this horizontal “umbrella” position, the panels will be able to produce 80% of their rated power. The benefits of protecting crops from damaging hail and heavy rain are evident, but many crops could benefit from the protection and shade control this system could offer. For example, this system could protect against sunscald, which can affect most crops in the right conditions and render them unmarketable. And, if grape growers could control sun levels, they could affect the acidity and sugar levels of the grape, which is very important in wine production. Many crops could benefit if growers could protect them with a solar panel covering, especially as weather conditions become more extreme. 

An umbrella effect is created when the solar panels are placed in a horizontal position and shifted over the top of each crop row.

Professor Hegedus believes that one of the biggest indirect benefits of proving this type of agrisolar system is that opposition to large solar installations on farmland might dissipate once neighbors realize that farming is not being replaced by solar panels but rather augmenting with an additional layer of income. He said, “farming is just carbon-based solar energy so now we’re combining two different ways of harvesting that energy.”  

The project’s researchers will be challenged by the quantity of data gathered from multiple sensors over a nine-month growing season at two locations. Advanced data analytic techniques will be necessary to organize and effectively interpret all the information. Future work will utilize the results from the study to form shading schedules that are tuned to each geographic and climate region to accommodate sun angle changes and local weather conditions so that the technology can be effectively utilized by farmers. 

In the face of climate change, well-designed agrisolar systems may give farmers a better chance to stay in business. Having the ability to protect crops and to control the shade levels could optimize production while at the same time producing revenue from solar power production, keeping farmland in production and profitable. Applications of this technology will be studied at UD in the coming years over the course of this project.  

Photos courtesy of Solagra.

Crops growing under solar panels at the Hawai’i Agriculture Research Center. 

By Anna Adair, NCAT Energy Program Assistant  

In Mililani, Hawai’i, a one-acre agrivoltaic research and development site run by the Hawai’i Agriculture Research Center (HARC) is working to grow fruits and vegetables for their community, while also discovering which crops grow best locally in an agrivoltaic setting. This agrisolar project is just one of many ways HARC has been working to foster and improve agribusiness in Hawai’i for over 125 years. The overarching goal of the project is to determine how to develop novel agricultural production systems for replication at commercial scale, while simultaneously increasing the productivity and profitability of agrivoltaic sites in Hawai’i.  

Nestled within a larger 230-acre solar system consisting of bifacial auto-tracking panels, the site is a collaboration between HARC, Longroad Energy, AES Corporation, and Clearway Energy Group, which owns the array. HARC researchers believe that agrivoltaic projects require research and development in the local environment to determine optimal infrastructure design, crop selection, and agronomic practices. With this in mind, agricultural construction and environmental monitoring began on-site in 2021. 

By June 2022, preparation for the first planting of crops underneath the panels began. Researchers treated the area for weeds, disked compost into the soil, and installed four lines of dripline irrigation in each raised bed. A total of eight 180-foot beds were constructed, containing 14 different crops for initial trialing: radish, daikon, melons, kabocha squash, broccoli, cauliflower, bush beans, eggplant, poha berries, bunching onion, lavender, strawberries, sweet potato, and dryland taro. While most of the plants were successfully cultivated, researchers considered the 2022 growing season to be a screening process that allowed them to choose which crops they will plant on a larger scale in the coming years.  

In addition to the in-ground plantings, hydroponic lettuce trials were also conducted in four commercial-scale troughs between the rows of solar panels. Five lettuce varieties were chosen based on what is most popular in commercial markets in Hawai’i . By December 2022, eight cycles had been harvested and yield data collected for detailed analysis as part of an ongoing graduate school thesis project at the University of Hawai’i .  

Agrivoltaic projects like this have the potential to help meet both energy and food production needs for the state, while simultaneously optimizing land resources. HARC has successfully demonstrated that agricultural activities can be conducted on solar sites with minimal impact to existing operations and will hopefully expand their research beyond a single acre plot in the coming years.  

Photo courtesy of Hawai’i Agriculture Research Center. 

A variety of chile pepper plants grow under solar panels on the roof of Colorado State University Spur campus.

Written for the AgriSolar Clearinghouse by Allison Jackson, Colorado Agrivoltaic Learning Center

Sitting atop the brand-new Hydro Building at Colorado State University’s Spur campus is one of the world’s first agrivoltaic rooftops. The 46-kW array is a southeast-facing fixed array. Half of the array has monofacial monocrystalline panels, while the other half has bifacial panels. The roof’s infrastructure was completed in April of 2023 followed by crop planting later that month. Dr. Jennifer Bousselot is an assistant professor of Horticulture and Landscape Architecture at Colorado State University and the lead researcher for the rooftop agrivoltaics site. There are a variety of experimental plots planted under each panel type, along with a control plot in the open sun, which includes performance experiments on chile peppers, medicinal herbs, leafy greens, and sown meadow plots.  

Dr. Jennifer Bouselot showcasing the sown meadow garden on the CSU:Spur Terra building.

Being situated on a rooftop comes with even more challenges than a typical agrivoltaic site. The wind loads on a roof make it challenging to install a tracking system, and the solar array requires membrane penetrations at every post or a ballast system under the soil substrate to ensure that the panels are secure. Irrigation is also trickier as green roofs have a well-drained substrate. This makes drip irrigation ineffective as water moves too quickly through the substrate profile for roots to absorb the water. The costs to locate agrivoltaics systems on rooftops is substantially increased due to higher engineering costs and the difficulties of moving and installing all the materials high in the air. 

Medicinal herb and chile pepper experimental plots under the monofacial solar panels.  

It is obviously early days for this agrivoltaics site, but some differences were already evident. Based on measurements, available light was higher under the monofacial panels than under the bifacial panels. In the chile pepper experiment, the agrivoltaic plants had reduction in chlorophyll concentration (due to less light), but also a reduction in stomatal conductance (a proxy for water use). The chile pepper plant height was also affected; the plants were up to 5 cm shorter in the open sun as compared to under the panels. The same also held true for the leafy green experiment, —the leafy greens (like kale, chard, arugula, spinach, and lettuce) under the solar panels were larger as compared to the full sun. The plants in the shade reached higher and created larger leaves to collect the necessary amount of sunlight.  

Chamomile plants in agrivoltaics system (left) versus full sun application (right).

The flowering of the medicinal herb plants seemed to be delayed for the agrivoltaic plants as opposed to the full sun plants, as seen in the photo above. On the positive side, the pigment content (a measure of potency) of the herbs was slightly higher in the agrivoltaic plants. It is only partially through the first growing season, with still more data collection to be completed, but it is interesting to note some of the early results.  

Incorporating agrivoltaics on rooftops presents an innovative synergy of renewable energy and sustainable agriculture. These sites can make urban spaces not just consumers of resources, but also active contributors to both energy and agricultural production. By harnessing the power of the sun through solar panels while simultaneously cultivating edible and useful plants, this innovative approach can maximize land utilization, reduce urban heat island effects, and foster local food production.  

Photos courtesy of Allison Jackson, Colorado Agrivoltaic Learning Center.

By Allen Puckett, NCAT Technical Writer 

August 2023 

In Ballground, Georgia, Jeffrey Whitmire and Chris Ayers, owners and operators of Chiktopia, are making use of an innovative solar technology that allows them to automate pastured poultry production while also practicing regenerative agriculture. Whitmire and Ayers, both students at the University of Georgia, produce and use fully automated solar-powered chicken coops on their operation, which they also sell to other farmers. In addition, Chicktopia provides regenerative grazing services to farmers. 

These solar-powered chicken coops assist in building the topsoil (regenerative agriculture) using chickens. The self-moving, automated chicken coops makes spreading manure and flock rotations much easier for farmers and results in healthier soil with a higher level of organic matter. Chiktopia suggests that automated equipment such as these solar chicken coops are mandatory for regenerative agriculture in the future.  

“At Chiktopia we believe sustainable farming practices are not only what are best for the planet but are also what create the happiest animals and the healthiest food. We help farmers minimize labor and maximize management. 

Our automated chicken coops use renewable energy systems, which automate the majority of the labor in the pastured-poultry process. Whether it be for broilers or egg-layers our coop will help save you time and labor.”Chiktopia 

Chiktopia aims to help build a more resilient food system across the United States using pasture-raised poultry, says Whitmire. 

The Regenerative Process 

If a farmer wants a section of land to be converted into a regenerative crop farm, Chiktopia provides that service and process. The first step in the process is to put egg-laying hens on the land in the mobile, solar-powered coops. Once the hens are rotated through the whole pasture, dairy cows are then put on the land to spread more manure. This last step of the grazing process allows the soil to sustain more vegetation through increased microbe quality and carbon sequestration. This improvement in soil health is known as regenerative grazing.  

Traditional Chicken Coops 

A traditional chicken coop is made of steel and must be manually lifted or moved using a handle or trailer hitch on one end. This requires much more manual labor than having an automated coop. Moving these traditional coops causes the pasture to be damaged when chickens spend too much time in one spot. The mobility of the new solar-powered coop keeps the chickens from destroying the pasture and allows the organic matter in the soil to regenerate. 

Solar-Powered Chicken Coops 

The solar-powered chicken coops are equipped with an automated temperature-control system, automated chicken feeder, sun-tracking solar array system, automated pressurized watering system, automated egg collector, and even heat lamps for young chicks. These coops have a traditional hitch for farmers who might prefer moving the coop with ATVs or trucks, but they can also be easily moved with a handheld remote control. 

When the coop moves, the birds don’t seem to mind at all. On the outside of the coup is an electrified perimeter fence that keeps the chickens in and predators out. When the hens are first put on a specific site, they spend a couple days in the coop getting comfortable with the new location, says Whitmire. They are then let out of the coop into the fencing area where they can roam. 

The floor of the mobile coop is lined with plastic netting that allows the bird manure to fall to the pasture below. Feeders are aligned on the two sides of the coop above the netting where the birds tend to spend most of their time. When they aren’t feeding, there is a ladder in the center of the coop that allows the birds to get up near the ceiling and roost on installments designed for chicken roosting.  

These automated, solar-powered chicken coops are available to order on  Chiktopia’s website. Depending on the needs of the farmer and the design of the coop, costs can vary, ranging from $8,000 to $20,000. One coop created by Chiktopia houses up to 400 birds. 

Predation Prevention and Shelter  

These coops provide effective predation prevention. The sturdy cover provided by the coop protects hens from hawks and other predatory birds when they are inside. The coop’s design also reliably provides protection from harsh weather and other conditions that may make the birds uncomfortable or unsafe. 

We keep our birds protected through using strong materials on the coop and an electrified fence. Solar panels also reflect light at raptors.” – Chiktopia  

Future Improvements 

Chiktopia plans to make improvements to their coops, including a rainwater diverter that puts water directly into the watering tank that will be available to the chickens.  

“Our birds have never been happier, and collecting eggs has never been easier! Daily movements are easy because the coop moves itself.” We were not able to move our birds on pasture before we had an automated Chiktopia coop.” Chiktopia customer 

By Chris Lent, NCAT Agriculture Specialist

The concept of agrisolar—the use of land for solar electric and agricultural production—is becoming a popular idea. It captivates the imagination to think of the many ways we can use a limited land base to produce…

By Allen Puckett, NCAT Technical Writer

In Harrodsburg, Kentucky, a flock of sheep is successfully grazing on a solar array at the E.W. Brown Farm, thanks to a collaboration between Shaker Village of Pleasant Hill and LG&E. This operation is Kentucky’s largest solar farm, consisting of 44,000 solar panels on 50 acres.  

Shaker Village’s flock grew from 125 Shetland sheep to more than 200 sheep—with 15 ram and ewe lambs born in Spring 2023, and more expected in the near future.  Of these 200 sheep, more than 50 moved to the Brown Solar facility in April of 2023. 

Photo credit: LG&E

Utilizing sheep on the solar array is not only more environmentally friendly, but it will also save the company and its customers money in the long-term by offsetting the cost of using traditional (gas-powered) lawn mowers. Managing vegetation with sheep is also safer than using traditional mowers and weed eaters beneath and around solar panels, according to the E.W. Brown farm. 

By using sheep to graze what is Kentucky’s largest solar farm, instead of lawn mowers, we’re being more environmentally friendly and holding down maintenance costs for our customers,” said Aron Patrick, director, Research and Development. “What started as a research project is laying the foundation for sustainably integrating more solar generation into our portfolio, and we hope the unique way we’re managing it can be a model for solar sites around the world.” – https://lge-ku.com/sheep  

Photo credit: The Harrodsburg Herald

Shaker Hill uses Shetland sheep, a heritage breed, on the E.W. Brown solar site. This breed originates from the highlands of Scotland and was common in the 19th century when the Shakers occupied the Pleasant Hill area. This allows Shaker Hill to connect their farm story directly to the Shaker’s agricultural history. Also, importantly, Shetlands are a smaller breed of sheep, and their size allows them to access the hard-to-reach areas of the solar arrays, whereas a larger breed might not be as efficient in maintaining vegetation growth. Shetlands are also known for their resilience in poor forage conditions, long life span and natural lambing ability.  

We’re happy to provide a green and sustainable way to help care for our neighbor’s land,” said Shaker Village farm manager Michael Moore. “Our farm gravitates toward heritage breeds, like Shetlands, that were raised by the Shakers of Pleasant Hill. This allows us to connect our farm story directly to the agricultural history of this region.” 

The 50 sheep moved to the site in April 2023 will graze throughout the spring, summer and fall, and then they will be transported back to the Shaker Village Farm for the winter months.  

Photo credit: LEX Today

There are also two Anatolian Pyrenees cross-bred dogs on-site that aid in protecting the sheep from predators. The guardian dogs live with and provide protection to the flock year-round. The team at Shaker Village manages the daily care of the dogs. 

The successful partnership between Shaker Village, LG&E has inspired the launch of the children’s book, Levi the Lamb’s Big Day. The book follows a sheep named Levi as he grazes a solar facility. The book was written by LG&E and KU manager of Technology Research and Analysis, Aaron Carter, and is available for purchase online or at the Shaker Village Gift Shop. 

Photo credit: WDRB

Shaker Village also has a “ewe tube” camera, where people can watch a live feed of the solar array. You can watch the sheep graze the facility here.