The agrivoltaics approach to pairing crop and solar production draws on topics from many different disciplines, including agriculture, solar energy, engineering, economics, and environmental science. As a result, discussions often include terms that may be unfamiliar.

Here, we introduce five terms that appear frequently in agrivoltaics conversations related to light, climate, water, and land.

Photosynthetically Active Radiation (PAR)

Photosynthetically active radiation refers to the portion of sunlight that plants use for photosynthesis. It includes light wavelengths between 400 and 700 nanometers.

In agrivoltaics, PAR matters because solar panels reduce and redistribute incoming sunlight. How much PAR reaches crops beneath or between panels helps explain differences in growth, stress, and productivity.

Daily Light Integral (DLI)

Daily light integral describes the total amount of PAR a plant receives over the course of a day.

While PAR refers to the amount of light at a specific moment, DLI is cumulative light exposure over an entire day. Changes in shading patterns in agrivoltaics systems can increase or decrease DLI depending on system design, time of year, and location.

Partial Shading

Partial shading occurs when solar panels block a portion of incoming sunlight rather than fully shading the ground.

In agrivoltaics systems, partial shading varies depending on panel height, spacing, orientation, and tracking behavior. It influences how much light reaches crops, how heat builds up near the ground, and how water moves through the system, making it a central concept in understanding agrivoltaics outcomes.

Microclimate

A microclimate refers to localized environmental conditions near the ground, including temperature, humidity, wind, and radiation.

Solar panels can modify microclimates by providing shade, reducing surface heating, and altering airflow. These localized changes are often used to explain observed differences in crop performance and soil conditions under agrivoltaics systems.

Evapotranspiration (ET)

Evapotranspiration is the combined loss of water through evaporation from soil and transpiration from plants.

In agrivoltaics systems, shading and microclimate modification can influence ET by lowering temperatures and wind exposure. Reported changes in ET and water use vary widely across studies and sites.

Land Equivalent Ratio (LER)

Land equivalent ratio (LER) is a simple concept: it compares how much land is needed to produce the same combined outputs when agriculture and solar are co-located versus when they are developed separately. An LER value greater than 1 indicates that a system co-locating two or more land uses is operating more efficiently than each land use individually. 

Early modeling studies of agrivoltaic systems have reported LER values as high as 1.7, meaning it would require 70% more land to produce the same amount of food and solar if done separately (versus the co-located approach).

These terms frequently appear in agrivoltaics research and project descriptions. Understanding this shared vocabulary makes it easier to interpret study findings, evaluate demonstration projects, and engage in informed discussions about agrivoltaics outcomes.

Future posts will introduce additional terms, including those related to system design and economic feasibility. As always, if you have a specific question or topic you’d like us to address, let us know.

“Agri(culture)” plus “(photo)voltaics”

Agrivoltaics is an approach to integrating agriculture and solar energy production. Unlike conventional solar, where agricultural use is displaced, agrivoltaic systems are designed to maintain productive farmland below or between solar panels. Systems are designed to act symbiotically with the environment in order to harness multiple benefits that ultimately take care of the land while growing revenues. This dual-use approach is gaining attention as interest grows in using resources more efficiently to meet food, water, and energy security goals. 

How are agrivoltaics used?

You may run across many different terms when researching Agrivoltaics: agri-pv, ag-solar, solar grazing, eco-solar, conservation solar, farmer friendly solar, etc. We’ll do a deep-dive on those terms and the differences in a later post. 

To keep things simple, there are three main ways to combine agriculture and solar:

• Animals - Some agrivoltaic systems pair with livestock, such as sheep grazing beneath and between panels.
• Pollinator - In other cases, solar arrays are paired with pollinator habitat that provides ecological services while maintaining land productivity.
• Crops - At HARVEST California, we are especially interested in agrivoltaic systems that are designed to support crop production by spacing or elevating panels so that plants receive sufficient sunlight and farm equipment can operate normally.

Why do agrivoltaics outcomes differ?

An important agrivoltaics consideration is that outcomes are highly context dependent. Crop type, climate, soil conditions, light availability, and solar array design all influence how agriculture and energy interact on a given site. Panel height, row spacing, tilt, and tracking behavior may also affect how much sunlight reaches the plants. Design choices directly shape agricultural outcomes.

Focusing on agrivoltaics systems that pair solar and crop production, multiple studies have documented positive effects, including long-running experiments at University of Arizona’s Biosphere 2 Agrivoltaic Learning Lab, where researchers found cooler temperatures and improved soil moisture under panels compared to full-sun plots. In some cases, crop yield even increases with partial shade.

Here in California, one of the most promising benefits of agrivoltaics is water savings, which can reach 30% under some conditions. In future blog posts, we’ll dive into this opportunity that is gaining urgency with the state’s Sustainable Groundwater Management Act (SGMA) compliance requirements rapidly approaching. 

New to agrivoltaics and have a specific question you’d like us to address? Reach out.

While California remains one of the most productive agricultural regions in the world, known as the “salad bowl” of the U.S., the amount of land actively used for agriculture has been decreasing since the 1980s. Without taking new conservation measures, California is projected to continue losing farmland at a rate of roughly 50,000 acres per year - equivalent to more than one and a half times the area of San Francisco annually - according to the California Climate and Agriculture Network.

Understanding the pressures shaping today’s land-use decisions is essential for evaluating how new land uses can play a role in maintaining California’s position as the leading agricultural producer in the nation.

Pressures shaping today’s land-use decisions

While urban development remains a primary driver of land conversion, other pressures – including decreases in groundwater, increased climate variability, and economic uncertainties – further drive loss of California’s working lands.

Water availability has become a central constraint on agricultural land use in California. Decades of drought and heavy reliance on groundwater have made reliable irrigation more uncertain, particularly in the Central Valley. Implementation of the Sustainable Groundwater Management Act (SGMA) is reshaping how groundwater can be used by requiring overdrafted basins to reduce pumping. In regions where agriculture relies heavily on groundwater, these limits can reduce available irrigation supplies, leading some land to be fallowed, shifted to lower-water-use crops, or removed from production altogether. Studies indicate that between 500,000 and 900,000 acres of agricultural land in the San Joaquin Valley may be taken out of production due to water scarcity in the coming years, as reported by American Farmland Trust.

Climate variability and rising temperatures compound existing water challenges. Heat waves and longer dry periods are becoming more frequent, increasing irrigation demand and stress on crops. Some climate projections indicate considerable impacts on major California crops. For example, as reported by National Public Radio, yields for several fruit and nut crops such as grapes and almonds could decrease by 20-40% by 2050 due to increased daytime temperatures and reduced overnight chill hours. These shifts add uncertainty to production decisions and long-term planning, especially for these types of specialty crops that dominate much of California’s agricultural economy.

Economic conditions also play a significant role in shaping agricultural land use. In California, average farm real estate values are among the highest in the nation, with the United States Department of Agriculture (USDA) reporting cropland values above $17,000 per acre in major agricultural regions. High land costs increase financial pressure on farmers and can make it difficult for smaller operations to remain viable. Additionally, expenses such as labor and agricultural inputs have sometimes grown faster than revenues, squeezing profit margins for many producers. These pressures are reflected in industry trends: between 2017 and 2022, the number of farms in California declined by more than 10%, with the greatest losses among smaller operations farming less than 180 acres2.

These pressures have increased interest in land-use approaches that seek to maintain agricultural activity while integrating additional activities that conserve water resources, mitigate climate change impacts, and diversify revenue streams.

The agrivoltaics opportunity

Within this context, agrivoltaics has emerged as an approach that integrates agricultural activity with solar energy production by maintaining productive farmland below and between solar panels. This dual-use strategy provides myriad benefits, including land-use efficiency, which we’ll explore in future posts. 

As interest grows in agrivoltaics as an important contributor to land and natural resource conservation efforts in California, we at HARVEST California are committed to helping stakeholders across the state understand and evaluate the opportunity to pair crops and solar. To stay up-to-date on the rapid evolution of agrivoltaics in California, subscribe to our monthly newsletter. 

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