Written by Larry Gosselin, Julie Lowe, and Richard Rollins
Agrivoltaics, which pairs solar panels (photovoltaics) with agriculture, is a double-duty climate solution that yields benefits to farmers while minimizing the Nation’s need to use undeveloped natural lands for solar energy development. By putting aside the historical practice of devoting land to a single purpose, this approach could make it easier to achieve the goal of decarbonizing the economy by 2050.
Agricultural land in the contiguous 48 states accounts for about 55 percent of the total land area (or about 1.65 million square miles) used for growing crops, animal grazing and farmsteads/farm roads.1 Historically, nearly all agricultural land has been dedicated to converting energy from the sun into stored energy in the form of food or other useful products. However, in the past few years, the idea of adding a new product — electricity— to the mix has taken root.
In fact, the topic has garnered the attention of the U.S. Senate, thanks to two new bills to support agrivoltaics, by spearheading its growth and by creating habitats for pollinators underneath the panels.
The United States Department of Agriculture (USDA), National Renewable Energy Laboratory (NREL) and the Department of Energy (DOE) have all recognized the potential of producing electricity on agricultural lands.2 3 4 In its 2021 Solar Futures Study, the DOE estimated that about 0.5 percent of the contiguous U.S. surface area would be required by 2050 for a carbon-free electricity grid and a high level of decarbonization. For a completely decarbonized economy, the area required is roughly twice that at one percent.5 The report also noted that combining solar energy and agriculture can provide multiple benefits to rural communities.6
Achieving Decarbonization Goals
A recent report released by Princeton University estimates the new renewable energy projects needed for the United States to meet its future decarbonization goals.7 Agrivoltaics can help address the problem of where to place the new projects. This dual-use of agricultural lands reduces the demand for new land development, furthering the goal of leaving undeveloped natural lands undisturbed. In turn, it would help advance President Biden’s 2021 Executive Order to protect 30 percent of the nation's lands and waters by 2030.8
The American Farmland Trust describes agrivoltaics as co-location of “solar energy production and agricultural operations. Combining these practices into one space creates an efficient and sustainable land use system that benefits farmers, solar developers, rural communities and the earth itself.”9 The DOE’s InSPIRE project provides a more nuanced account, identifying three general configurations:10
- Solar centric – designed with minimal changes to the arrangement of the solar arrays, but with low-lying vegetation for ground cover and habitat.
- Vegetation centric – minimal changes to crop layout with solar arrays widely spaced or located at field margins.
- Co-location and co-optimization – Solar and vegetation configurations designed jointly for maximum dual output.
Preserving Undeveloped Land
Agrivoltaics is a more palatable solution compared with large-scale commercial solar energy projects that require mass grading or removal of fertile topsoil to achieve a standardized slope, installation of a gravel cover, and application of herbicides for the full life of the project to control weeds. These projects can eradicate existing vegetation and essentially prohibit any future agricultural use on the land.
Ensuring the Success of Agrivoltaics
Varied results from recent and ongoing research make it clear that agrivoltaics is not a one-size-fits-all approach. Its utilization depends on many variables, including the proximity of high voltage power lines and electrical substations, as well as the landowner’s priorities. In August 2022, the NREL released a report summarizing lessons learned from the DOE’s InSPIRE project since its inception in 2015.11 The report categorized important factors that contribute to the overall success of agrivoltaics, and identified the variables that project proponents or landowners should consider as The 5Cs:
- Climate, Soil and Environment
- Configurations, Solar Technologies, and Designs
- Crop Selection, Cultivation Methods, Seed Selection, and Management Approaches
- Compatibility and Flexibility
- Collaboration and Partnerships
To better understand the potential of agrivoltaics, it's important to look carefully at stated or potential impacts and benefits, along with practices that can amplify benefits while minimizing negative impacts. For example, concerns about whether agrivoltaics will reduce cropland available for food production often diminish if the land itself is marginal, needed irrigation water is unavailable, or soil fertility has been compromised by salt or mineral accumulation. Concerns about loss of cropland for food production can also be tempered by recognizing that about 40.5 million acres, or more than 63,000 square miles, of the nation’s farmland are used to grow corn for ethanol production.12 Without any loss of cropland for food production, it is conceivable that this same land could be repurposed for dual-use agrivoltaics, growing crops in a less resource-intensive and more environmentally friendly way while simultaneously harvesting energy from the sun and converting it to electricity.
Some concerns about agrivoltaics are justified, but others are not. The impact of an agrivoltaics installation depends on unique factors that differ from location to location, from community to community, and on the details of a particular project. Agrivoltaics is not implemented from the contents of a one-size-fits-all box. Rather, it is a novel dual-use strategy to be implemented on a case-by-case basis. Concerns can often be minimized by thoughtful engagement between solar developers and planning agencies to discuss construction details and mitigation options.
Detractors may see agrivoltaics as a slippery slope leading to industrialization of farmland. While this concern is important to keep in mind, construction methods that spare topsoil, minimize soil compaction, include pollinator habitat, and employ easy-to-remove mounting systems improve the feasibility of returning the land to agricultural use in the future. On the other hand, some farmers and rural residents simply don’t want to see solar arrays, preferring a more bucolic view of rural America, or believe politicians and developers to be insensitive outsiders working for profit without due concern for rural communities.
Wildlife can be impacted in both positive and negative ways, depending on location of the array, its size and construction details. Agrivoltaics with native pollinator vegetation and either no fencing or wildlife-friendly fencing can often provide a more compatible habitat than intensely cultivated farmland while still providing income for the farmer. Riparian areas and marginal farmlands may be preserved for wildlife corridors or habitat, and can mitigate some of the impacts on wildlife of larger agrivoltaic sites or more intensively cultivated farmlands.
Benefiting Farmers and Rural Communities
On the positive side, increased income to smaller family farmers is often viewed as a significant benefit. Carefully written lease arrangements can provide steady income to the farmer, while still allowing agricultural use under the solar array, whether it be for food production, grazing or planting of native vegetation that, over time, can increase soil fertility. Leasing guides prepared by the AgriSolar Clearinghouse and the Farmland Information Center provide valuable information to farmers who are considering a land lease to a solar energy developer.
Rural communities that embrace agrivoltaics can often benefit from increased tax revenue and a more diversified economy. Even a minimalist approach to agrivoltaics (only planting native pollinator habitat under the solar array) can reap multiple benefits, including better pollination of nearby crops or orchards, reduced or eliminated cost for pesticide application, and improved ground water recharge and soil health. In arid or semi-arid regions, shading created by solar arrays can help retain soil moisture, reduce need for irrigation, or enhance productivity of alternative crops.
Among other potential benefits associated with agrivoltaics, the increased overall efficiency of how society harvests energy from the sun is significant. A recent analysis looked at the energy investment on a given acre of farmland and the net energy produced, comparing agrivoltaics with growing corn for ethanol production. Using Energy Return on Investment (EROI), the study concluded that net energy production by photovoltaics was 100 to 125 times greater than net energy production from corn-based ethanol processes — a huge advantage.13
For More Information
Ongoing research and the growing number of active agrivoltaic projects are improving both the quantity and quality of the information available about agrivoltaics. The links in this article, especially those to USDA, DOE, or NREL resources, can be a good start for many people. Other sources include the AgriSolar Clearinghouse, a nationwide hub developed by the non-profit National Center for Appropriate Technology, and the Farmland Information Center, a project of the non-profit American Farmland Trust. The DOE InSPIRE website provides an interactive agrivoltaics map of more than 300 agrivoltaic projects including at university and other research sites.
Be sure to check out the Fall issue of The Climate Activist newsletter for our next article on agrivoltaics, which will focus on best practices, land use policies and more.
If you have a suggestion for a future blog topic or are interested in joining the team, please reach out to us at climateemergency[at]sfbaysc[dot]org.