Can Agrivoltaics Eliminate Land-Use Conflicts? More Research Could Tell Us Whether They Are Ready to Scale

Agrivoltaic (AV) systems have been touted as a solution to rising fears around solar energy expansion contributing to the loss of U.S. agricultural land. Most broadly, agrivoltaics can be defined as the co-location of solar panels and agriculture on the same land. Using farmland to not only grow food, but also produce clean energy sounds like a win-win given that land used for agriculture often has many characteristics that make it ideal for solar power generation.

And yet, solar’s historic and projected contribution to agricultural land decline is relatively small. Furthermore, AV systems have a long way to go before they will be able to effectively mitigate any conflicts around land use. The vast majority of AV sites today do not involve actual food production. A dig into the state of the science evaluating AV systems reveals that more research is needed across types of agricultural operations and regions to determine under what circumstances widespread AV systems would actually generate net climate benefits.

Federal funding through the Departments of Energy and Agriculture for this emerging industry more than tripled from 2021 and 2022. USDA provided several million dollars to AV projects through its climate-smart commodities effort in 2022 and environmental advocates continue to ask Congress to dedicate additional research dollars to this area, calling AV systems a promising climate solution.

Sweeping plains of food crops interspersed with solar panels generating clean energy – a vision of a rural America that is both maximally productive and contributing to the green transition. It’s an idyllic picture of a future where agriculture and clean energy coexist. But serious questions persist around technological feasibility, cost, financial incentives, and the yet-to-be-quantified tradeoffs with agricultural productivity.

What is Agrivoltaics?

The Department of Energy defines AV systems (or dual-use solar) as “agricultural production, such as crop or livestock production or pollinator habitats, underneath solar panels or adjacent to solar panels.” But the term “agrivoltaics” has also been used loosely to describe utility-scale solar where vegetative cover, such as native grasses, are planted beneath fenced solar panel installations.

Co-locating solar panels with vegetative cover requires minimal changes to traditional PV panel architecture and primarily serves to prevent soil erosion that can cause decreased electricity output, infrastructure damage, flooding, and other negative environmental impacts. This is a best practice for solar developers, not an attempt to co-locate solar energy with food production.

To manage vegetative cover, many sites incorporate livestock grazing. Sheep are the most common choice today. Their agility, smaller size, and grazing habits allow them to navigate easily around solar panels with less risk of damaging the infrastructure than larger livestock. In most cases, sheep are introduced primarily for grazing purposes, not food production.

Existing AV sites, by any definition, remain limited both in number and scale in the U.S. According to the National Renewable Energy Laboratory’s Agrivoltaics Map, there were 588 AV sites across the U.S. this year. The vast majority of these sites (85%) have a capacity of less than 10 megawatts. All of these AV sites combined produce about 10,000 megawatts—less than 1% of the administration's 2050 target of 1,570 gigawatts of solar deployment. This raises considerable doubts for the potential for these sites to meaningfully contribute to the Biden Administration’s goals.

The majority of these sites are utility-scale solar operations where pollinator habitat or native grasses have been planted underneath. Very few, including those in research settings, involve crop production or livestock raised for food. Of the nearly 600 AV sites spanning the U.S., 233 sites incorporate livestock grazing, almost all of which use sheep for vegetative management. Only 35—less than 6%—include crops grown beneath solar panels. Of those, a mere 8 sites with panels co-located with crop production have a capacity greater than 1 megawatt.

Producing Food with Agrivoltaics is Expensive and Tech Intensive

Co-locating solar production with actual agricultural production, rather than just vegetative cover, is far more difficult for solar developers to pursue, both technically and financially.

In order to co-locate solar panels with commodity crops, specialty crops, or livestock grazing, panels can be elevated to allow animals, taller crops, or farming equipment to exist beneath. Alternatively, increased spacing between rows of solar panels can allow crops to grow and farming equipment to pass in between (commonly called inter-row systems).

Both of these options introduce fixed infrastructure on agricultural fields and often come with added costs. Installing agrivoltaic panels are often more expensive than traditional solar panels used in utility-scale installations, requiring additional specializations and settings.

AV systems also add complexity when it comes to planning, design, and permitting, adding costs to a project. Configuration and solar infrastructure design, for instance, impact solar energy generation efficiency. This is primarily due to panel spacing. In solar-only systems, profits typically increase with the density of the solar panels. Solar developers and their insurers are also often averse to locating farming machinery and animals in close proximity to expensive solar infrastructure.

Today, about half of existing AV sites utilize single-axis tracking arrays, which are systems that follow the sun as it moves across the sky. These are more expensive than fixed-tilt systems, but the increased cost is often offset by their higher energy production. These energy gains are even more important in agrivoltaic systems, where solar panels are arranged with less density, compared to solar-only systems, leading to lower energy production per acre. Currently, no AV sites use dual-axis tracking, which tilt on two axes allowing for better tracking of the sun across seasons. In addition to being more expensive and having added mechanical complexity compared to single-axis tracking or fixed-tilt systems, dual-axis tracking systems involve a greater range of motion, which can make it more challenging to avoid interference with densely planted crops or areas where agricultural machinery needs to pass. Promising research out of Purdue University has adapted traditional solar structures to improve compatibility with large-scale agriculture and reduce costs associated with panels that are mounted high off the ground. The patent-pending structures use a dual-axis tracking to capture more sunlight and to tilt vertically when farm equipment needs to pass by.

Inter-row systems require additional spacing between panels and crop rows, reducing density of the panels compared to a non-AV utility-scale solar site. In solar-only systems, the level of profits usually increases with the density of the panels, but this can be at odds with optimal conditions for crop yields. One optimization model for vertically mounted agrivoltaic systems found that row distance between solar panels significantly affects crop yield; oat and potato yields, for example, fell by about 50% as row distance decreased.

These technology-specific specifications and configurations increase the costs of AV systems relative to solar-only configurations. Benchmarking analysis in 2020 found AV grazing, pollinator habitat, and crop production systems to all be more expensive than conventional designs mounted over bare ground. Costs were highest for AV systems with crop production, costing up to $0.80 more per watt of capacity. To meaningfully cut emissions, the costs associated with tailoring AV systems for specific regions, climates, and operations will need to come down.

One study funded by NSF and USDA found that AV systems bear an extraordinarily hefty price tag. The study determined AV systems could meet 20% of the nation’s total electricity generation, but will require a $31 billion per year investment in rural infrastructure. That’s more than the entire annual budgets of USDA and FDA combined. The authors also contend that many of the benefits of AVs, including reduced emissions and job creation, are also applicable to solar-only systems and other forms of renewable energy, all at a lower price point and lower area per unit of energy. Investing this level of funding in the deployment of AV systems is a poor choice for taxpayer dollars, given the high cost today and many uncertainties that deserve additional R&D.

Further research efforts are needed not only on new AV technologies and system designs, but also to examine the effects of solar installations on revenue and production on agricultural land.

Evaluating the Potential of Agrivoltaic Systems

Even if solar developers prioritized deployment of AV systems, despite added costs, farmers and landowners need to be convinced of the benefits. As several studies show, the cost-benefit calculation made by landowners is a primary predictor of AV adoption.

Proponents of AV systems highlight potential producer benefits, including diversified revenue streams and increased farm income. However, landowners could reap similar benefits from utility-scale solar leases that take land out of agricultural production entirely. A growing number of farmers report having discussions with solar developers. Of those that already have, almost 70% report being offered a long-term lease rate of $1,000 per acre or more. Recent survey data shows that nearly 70% of U.S. farmers are open to large-scale solar, with a significant number of respondents indicating their support is conditioned on dual-use system designs that allow for continued agricultural production. (It’s important to note that the benefits of leasing land to a solar developer will only be reaped by farmers that own their property. About 60% of U.S. farmland is owner-operated.)

Landowners will need to assess whether AV systems are more lucrative than leaving their land in agricultural production or leasing their land for solar-only systems. On rangeland and pastureland, this means assessing the value of integrating livestock grazing with solar energy generation. On cropland, this means evaluating whether AV systems will reduce their agricultural yields and if any losses are worth it.

Livestock, particularly sheep, are being used as tools for vegetative management in solar energy systems. While cattle are sometimes used for this purpose, sheep are far more common in solar projects. Of the nearly 600 AV sites across the United States, 40% incorporate livestock grazing, with sheep being the primary choice in all but three sites using cattle. While most agrivoltaic research to date has focused on systems that incorporate livestock focus on sheep grazing, the body of research on systems that include beef or dairy cattle is growing.

Researchers in Minnesota have studied whether shade provided by solar panels could reduce heat stress and improve overall health of cattle in pasture-based dairy systems. However, more research is needed to go beyond evaluating any potential benefits or harms to animal wellbeing and productivity to assess the profitability of integrating cattle grazing and solar, compared to solar-only systems. DOE recently launched an $8.2 million prize for pilot sites that incorporate solar with cattle grazing operations. This is a promising effort to gather data that will help inform best practices, project costs, and evaluate energy and agricultural outcomes in these AV systems.

Much more research has been done on how solar panel configurations, system design, and plant selections affect both crop and energy production across climates, soil types, and management practices. Yet, there is still disagreement across the literature on the advantages of AV systems when it comes to yield. For shade-intolerant crops, like corn, optimizing panel density for solar generation often tends to decrease plant productivity. Low-density AV systems have been shown to increase sweet corn yield, but a high-density system decreased yield.

Shade-tolerant crops like lettuce have been theorized to be good candidates for AV systems as they would be less likely to suffer crop yield losses. Lettuce is one of the most studied vegetables in academic papers analyzing agronomic data in AV systems. Despite this focus, yield impacts remain far from definitive. Average lettuce weight has been found to either significantly decrease or slightly increase under solar panels, depending on the study. Efforts to synthesize across the literature have found yield changes to be similarly inconsistent across studies of tomatoes under AV systems. Potatoes have been found to grow well under AV systems with above average yields and minimal impacts to quality, while significant decreases in yield or biomass production were observed for garlic, onion, and spinach. Generalizable findings across regions and crop types are still lacking.

Very few studies have examined how these yield trade-offs impact the profitability of AV systems compared to a crops-only option, and even fewer compared to a solar-only option. Some have concluded that AV systems are better suited for organic specialty crops that have a price premium. A synthesis of those available suggests that in instances where combined income from agricultural output and electricity generation under AV systems exceeds that of a crop-only system, the primary driver of the increased combined income is often energy production. These economic analyses indicate that the combined crop and energy output from AV systems can, under certain conditions, lead to greater overall income compared to relying solely on agricultural production.

However, there remains large variability and uncertainty across existing profitability estimates due to limitations in applying localized studies to other regions or larger operations, variation in yield potential and market values for different crops, and a greater focus on short term payback periods rather than long-term profitability. While there are indications of profitability under certain conditions, widely varying results make it difficult for stakeholders to make informed decisions based on existing research.

Environmental advocates need to grapple with the implications of crop yield tradeoffs in AV systems, even if the overall profitability of such systems is net positive. One of the primary drivers of research on AV systems is the potential to mitigate land-use conflicts. If solar and crop production can occur on the same acreage without sacrificing efficiency or productivity, there is no need to worry about indirect land-use change emissions stemming from reduced agricultural production. To avoid these leakage tradeoffs, however, crop productivity under AV systems needs to remain the same or increase. Any reductions in crop productivity under an AV system (ie. requiring more land or shrinking margins per acre) need to be accounted for when assessing net climate benefits compared to crops-only or solar-only set up.

Several studies using land use models and lifecycle assessments predict AV systems in Germany can have net environmental benefits and result in net carbon emission reductions if primarily implemented on grasslands or when food crop yields are maintained under solar panels. Long-term research on the effects on yields for different crops under AV systems is needed to help inform robust land-use change assessments in other regions.

Beyond economic incentives, producers will also need to assess the impacts an AV system might have on factors such as soil carbon sequestration, soil health, and irrigation water use. Research is lacking to support the conclusion that AV systems enhance carbon sequestered in agricultural soils, with estimates showing variation depending on prior land use. Future research is needed to explore whether pairing AV systems with land management practices that reduce GHG emissions, such as soil amendments, would boost the overall climate benefit of AV systems compared with solar-only. These additions would likely generate added costs.

Improvements in soil moisture and decreased water use are commonly cited reasons farmers should consider the benefits AV systems would have on crops and vice versa. However, these benefits have been largely studied in systems where solar panels are co-located with pastureland or pollinator habitats, relative to solar-only systems. The benefits of these improved ecosystem services have not yet been considered in broader calculations for AV system costs compared to crop-only systems, nor for AV systems involving commodity crop production.

While AV systems offer the potential for diversified revenue streams, their profitability and subsequent adoption by landowners is contingent on a complex interplay of economic factors. More research is needed to address the knowledge gaps on the long-term impacts of AV systems on crop yields, expand research on how to combine solar energy installations with cattle grazing, develop robust economic models that include tradeoffs in agricultural production and energy generation under dual use scenarios, and provide farmers with comprehensive information to make informed decisions.

Future Agrivoltaics Research Questions to Inform Decision Making

AV system deployment will remain limited to smaller scale solar and niche crop types until significant design and cost breakthroughs for utility-scale projects emerge. To contribute to this effort, federal investments in AV systems should focus on funding and diversifying research projects in this space.

First, research should optimize AV system design for diverse applications. Research gaps remain for how to successfully implement AV systems across crop types, regions and production systems. With only 3% of U.S. farmland in 2022 growing specialty crops, acres growing commodity crops present the largest land potential to share space with solar panels. Research is needed to determine if and when commodity crop production will perform well in an AV system.

Second, future research should quantify land use efficiency tradeoffs between crop yields, livestock production, and energy generation in AV systems, relative to agriculture-only or solar-only systems. These tradeoffs should be assessed under varying conditions (ie. regions, agricultural production systems, crop varieties, local market conditions, and the efficiency of solar energy production) and be translated to impacts on profitability. Comprehensive studies are needed to estimate how any diminished agricultural productivity under AV systems impacts net emissions due to the effects of indirect land use change.

Furthermore, economic analyses are needed to translate agricultural production and solar energy generation tradeoffs to impacts on profitability. Direct comparisons between projected income from AV systems compared to agricultural production alone and to solar-only systems would help landowners to assess the value of diversified revenue streams.

Ultimately, the land-sharing benefits of AV systems must be weighed against their potential to meaningfully contribute to the clean energy transition. Addressing research gaps will help landowners and solar developers alike to right-size profitability and productivity tradeoffs when considering integrating solar and crop or livestock production on their land. Until these questions are addressed, federal investments in deployment efforts should be minimal and targeted to operations with established profitability and minimal productivity trade-offs when integrating agriculture and solar on the same acreage.

Long-term cost comparisons between AV systems and solar-only or other renewable energy options, along with cost estimates for needed rural infrastructure upgrades to support large-scale AV deployment, will help policymakers to assess what investments will maximize climate benefits within budgetary constraints. Until then, a major question for solar developers remains: when one can lease land to build utility-scale solar at a lower installation cost and with better energy generation efficiency, why invest in agrivoltaics at all?