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.