What are agrivoltaics and why are they important?

The term “agrivoltaics” refers to the simultaneous use of areas of land for both solar photovoltaic (PV) power generation and agriculture. The declining cost of PV technology and rising market and policy incentives for solar energy are making it increasingly profitable to convert cropland to solar farms, leading to a potential conflict with food crops. Agrivoltaics (AV), the co-located production of solar energy and crops, has the potential to reduce this competition for land and provide climate-smart solutions to improve land productivity (combined crop and electricity yield), crop water-use efficiency, profitability, and the economic resilience of agriculture. Deployment of AV systems in Asia and Europe is growing and there is increasing interest among farmers in the U.S. and globally.

What are the main roles of the partner institutions and researchers involved in this project? Why is it important to include different geographic sites?

The University of Illinois Urbana-Champaign is the lead institution. The Illinois team will partner with Dennis Bowman at the U of I Extension for agrivoltaics outreach activities. Additionally, the project features a combination of research, education, and extension activities at the University of Arizona, Colorado State University, Auburn University, the University of Illinois Chicago, and the National Renewable Energy Laboratory.

Research on AVs has been limited to isolated experimental studies on a few crops in a few regions. While encouraging, these isolated experimental trials with specialty crops do not provide generalizable evidence of the sustainability of AVs at scale. This is a key knowledge gap; increasing solar energy at the scale necessary to significantly reduce fossil fuel use cannot be accomplished solely on land currently devoted to specialty crops. Farmers are calling for a determination of crops and locations best suited for AVs, PV panel configurations that maintain or even increase crop yields, and contracts and policy incentives under which AVs are beneficial. Our proposed project for Sustainably Co-locating Agricultural and Photovoltaic Electricity Systems (SCAPES) will provide a comprehensive analysis of the transformative potential of AVs. Our goal is to maintain or even increase crop yield, increase the combined (food and electricity) productivity of land, and diversify and increase farm profitability with diverse crops (row crops, forage, and specialty crops) across three biophysically diverse regions in the U.S.: rainfed Illinois, dryland Colorado, and irrigated Arizona.

By encompassing such a variety of crop types and climatic conditions, we can make inferences beyond our specific measurements.  For example, the work being done in Arizona represents some pretty extreme conditions that are not typically representative of conditions in Illinois. Combining observations for Illinois and Arizona on wheat, for example, allows us to better understand the interactions of this crop over a range of conditions. Add on top of this the multi-year approach to this research, and we can better understand the opportunities presented by agrivoltaics in the context of normal climate variability and climate extremes. A strong focus on crop physiological measurements gives us the added benefit of identifying how our results might impact other crops that employ similar physiological strategies.

What climate factors are being compared between the locations?

We will leverage existing solar farms to assess microclimatic and plant responses to the presence of solar panels. Three research and demonstration sites will be established at the Energy Farm at Illinois, the Agricultural Research Development and Education Center at Colorado and the Campus Agricultural Center at Arizona. These sites will be designed to provide the full range of environmental and crop growth conditions in each of the three geographic regions with a specific focus on crop species with the attributes that our modeling identifies as most favorable for AV. Climate factors being measured/compared across the locations include soil, crop, and solar panel temperatures as well as air temperatures and humidity above, beneath and between PV rows and soil moisture. Additionally, we will monitor solar radiation above, beneath and around the PV canopy.

Will you use different arrangements of solar panels and crops at each site? How will they differ?

Yes. We anticipate that AV systems can be optimized to maintain, or increase crop yields while also producing solar energy. Optimization will be based on several performance metrics: (1) light transmission (2) water management (3) thermal energy and (4) mechanical optimization. These optimized AV systems are expected to differ across locations. To overcome the challenge of optimizing AV designs with the diversity of agricultural practices in the US, we will develop a coupled PV model and crop modeling framework that will be parameterized and validated with data from existing solar farms. This framework will represent light transmission and water- and thermal-dynamics in PV systems across regions and integrate it with crop growth models to co-optimize PV-crop design and placement.

What are the various arrangements of panels and crops intended to demonstrate (i.e., sunlight angles, sunlight exposure duration for crops, effects on irrigation, fertilization, and harvesting techniques)?

The experimental sites will be designed to provide the full range of environmental and crop growth conditions in each of the three geographic regions with a specific focus on crop species with the attributes that are most favorable for AV. Spacing between rows within an operational AV system must also consider farm machinery, irrigation systems, practical needs, optimized density of PV panels for yield, and landowner and PV-owner preferences.

We will design the experiments to capture the dynamics of sun and shade zones over space and time irrespective of row width. Almost all existing PV infrastructure is installed with electricity generation as the primary goal, so the space between the rows of panels is relatively narrow. Successful AV systems will likely require reduced panel density, or larger spaces between rows. Thus, these AV research facilities will allow us to parameterize our AV system models and validate their performance under a wider range of environments optimized for both crop and electricity production.

Is agrivoltaics something that could be widely used in the agriculture and energy industries? How soon might that happen?

Yes. Several states have started implementing policies that encourage agrivoltaics. For example, the Solar Massachusetts Renewable Target (SMART) program provides an agricultural solar tariff generation unit to incentivize dual use of agriculture and solar. These programs provide additional benefits to PV system owners in dual use applications. Furthermore, the interest in agrivoltaics is not limited to the US. There is a growing list of agrivoltaic projects in the European Union. Japan has implemented programs for PV and crop applications called “solar sharing,” and China has support polices for controlled environmental agriculture and rural economic stimulation that encourage agrivoltaics approaches.

Are there benefits to agrivoltaics other than the efficient production of food and energy?

In addition to potentially producing equal or greater amounts of food and renewable energy with reduced water use, we anticipate agrivoltaics systems can help society in other key ways:

  • Drylands are often really hot environments, making our farm worker population vulnerable to heat stroke and heat-related death.  Preliminary studies suggest that skin temperatures can be up to 20°F cooler when working under the PV array! That makes for significantly more comfortable working conditions!
  • Co-locating PVs with pollinator-friendly groundcover can also expand habitat for the declining bee population with significant implications for ecosystems and food production.

How will you encourage farmers to adopt agrivoltaics practices? What input will farmers have during this project? 

We will engage stakeholders to gain a shared understanding of the benefits, costs, interest and concerns with installing AV systems on farms and the information needed to advance adoption in areas where it is beneficial. Our team has extensive contacts with farmers, the Farm Bureau, the Sustainable Agriculture Research and Education (SARE) program, solar energy developers, the Solar Energy Industries Association (SEIA), and school educators. We will conduct initial focus group meetings to gather information on their interest, perceptions, and informational needs about solar and AVs.

We will also form Stakeholder Working Groups (SWGs) in IL, AZ, and CO, and an External Advisory Board (EAB) to actively advise SCAPES research, technology development, educational programs and extension engagement. Each SWG will include 15 to 20 members from each of the three locations and meet twice a year in their region. Additionally, an annual meeting of all three SWGs and the project team will be organized for cross-regional information sharing. Working with the SWGs, we will broaden the network of stakeholders that engage with SCAPES through focus group meetings to promote wider shared understanding of the costs and benefits of AVs to farmers, the acceptable synergies and trade-offs between food and energy production with varying AV designs, and desired attributes of contracts and policy incentives for AVs. These meetings will also inform us about the data needs and types of decision tools that would be useful for decision making by stakeholders. We will form an EAB consisting of representatives of the key stakeholder groups, educators and academics, which will meet once a year. They will review strategic goals and priorities, progress towards milestones, and identify gaps and areas to maximize our impact on producers and industry practices. Learning from interactions with the SWGs and the EAB will feed into the research and education tasks.

How will the educational app be developed and used?

We will design and implement a tablet-based app that enables interactive exploration of AV concepts. The app will model plant/crop growth, PV configurations and location-specific factors. The design will (1) enable pursuit of targeted learning objectives, such as how solar panels can protect certain crops from overexposure to the sun, (2) model the passage of time, and (3) allow calculation of land equivalent ratio (LER), and dollar to land ratio (DLR) under different conditions. The learner will simulate optimizations in their designs to assess acceptable trade-offs and synergies between food and energy production. The app will also be used in schools, summer camps, museums and focus groups with farmers to illustrate the choices, trade-offs and returns with AV. We are partnering with Balance Studios in Green Bay, Wis., known for their innovative work in science education and development of interactive and engaging public-facing technologies. To ensure that the app is effective in communicating the concepts of AV, our educational research activities will seek to rigorously demonstrate that the app increases knowledge and interest in AV.

What do you expect is the full potential of agrivoltaic systems in the following areas?

  • Energy production 

Studies have shown that PV panels with crops grown below are on average cooler (by about 8.9C) during day light hours than panels without crops. Because PV panels run more efficiently at lower temperatures, this implies potential benefits for PV energy yield, particularly in hot climates. 

  • Crop yields 

Early studies indicate that yields of some crops can increase under PV panel shade depending on climate and AV system design. Although yields may decrease for some crops, climates and system designs, overall, the studies to date indicate that agrivoltaics can provide synergistic benefits, particularly with further understanding and optimization of dual use site designs. 

  • Water use 

Water usage for some crops and grasses appears to decrease when the crops are placed below the PV panels, with greater water savings achieved in arid regions.   

— Article by iSEE Communications Intern Quinn Wolski