Agrivoltaic (AV) systems are dual-use land systems that consist of elevated solar panels with crops grown underneath. They offer a solution to the increasing demand for food production and clean renewable energy. The main concern regarding AV systems is the reduced availability of light to crops below the panels. Research to date shows that AV systems are quite productive with total energy and crop production exceeding the outputs of either solar farms or crop production alone. Research also shows that solar panels affect the microenvironment below the panels. The research on AV systems so far considers altering panel density to increase radiation to the crops by varying the distance between rows of panels in an AV solar array. This study examines the crop outputs for Swiss chard, kale, pepper, and broccoli in an AV system with different gap spacings of 2, 3, 4, or 5 feet (AV plots) between panel clusters within rows to determine how much spacing between solar panels is optimal for crop production by comparing these system yields to full sun crop production. This study also examines the effect of the AV system on crop nutrient levels, on soil water content, and crop leaf temperature below the panels. Ultimately, the biomass crop yields of AV plots are restricted significantly for Swiss chard, kale, or pepper compared against the full sun control plot yields but not for broccoli stem + leaf yields. The 4-ft or 5-ft gap distances between panels yield the highest crop biomass of the AV shaded plots. Nutrient levels tend to increase with more shade but the trend is only significant for Swiss chard nitrogen and phosphorus concentrations, pepper potassium concentrations, and broccoli phosphorus concentrations. For soil water content it is found that panels have some effect on evapotranspiration and rainfall redistribution at the soil level. Leaf temperatures in the AV plots are lower than leaf temperatures in the control plots on sunny days but not on cloudy days.

Large-scale carbon-free energy generation projects such as utility-scale solar energy (USSE) arrays help mitigate the energy sector’s contribution to climate change and are rapidly expanding throughout the U.S. However, the expansion of USSE sites is associated with immediate and longer-term ecological impacts, many of which have yet to be assessed. Quantifying the ecological impacts of USSE arrays will help to identify synergies and trade-offs between energy generation and terrestrial conservation goals. The overall goal of this research is to characterize the ecological impacts of USSE sites located on fallowed farmlands in San Luis Obispo County, California in a seasonally explicit manner. Fallowed agricultural landscapes and rangelands represent a particularly promising area for the deployment of solar arrays because these systems typically are significantly altered from their native conditions; therefore, array placement may not have significant further deleterious ecological impacts and may also provide the potential to recover ecologically with shifts in management practices. We studied how arrays impact a suite of ecological properties, focusing on two USSE arrays in California’s Coast Range Valley: Topaz Solar Farm (developed 2014)and Goldtree Solar Farm (developed 2018). Topaz, which is situated on previously disturbed agricultural land in Carrizo Plain, was seeded with a native seed mix prior to installation and uses rotational grazing to control vegetation growth. The climate is more arid at Topaz than at Goldtree, which is located approximately 14 miles from Morro Bay. Goldtree is situated on sheep pastureland and is also managed with a rotational grazing regime, though with a higher intensity than at Topaz. Solar farms created distinct patterns of heterogeneity, which then affected plant community changes and soil nutrient cycling. Partial shading in areas adjacent to panels increased species richness with more native species and higher functional diversity, especially in drought conditions. Full shading in areas directly under plots increased plant moisture content and plant nitrogen content during drought conditions. This may be beneficial in supplying plants with greater water availability and nutrients, especially during drought years. In solar array footprints, ecosystem respiration (plant and soil CO2 flux) was reduced, suggesting that shading on solar farms can improve carbon sequestration on disturbed agricultural land if organic matter inputs outpace carbon loss in this novel ecosystem. Thus, our study demonstrated that solar farms offer the potential for improvement of ecosystem services, if placed on previously disturbed landscapes such as fallowed farmland and combined with other conservation management practices.