Interactions between solar photovoltaic arrays and the underlying soil-vegetation system

Solar power is one of the fastest growing renewable energy sectors globally, driven by decreasing costs and favorable policies. However, solar energy production is land intensive and the large-scale deployment may negatively impact land and water resources. Considering the recent global concerns on transformation of agricultural lands for renewable energy development, the extent and type of land transformation must be quantified. In scenarios where agricultural or natural land is leased out for the lifetime of a solar project the soil quality may be negatively impacted and may provide challenges for reintroducing native vegetation or crops. Hence the impact of solar arrays on underlying soil and vegetation needs to be investigated for site preservation and for evaluating the potential to colocate crops or native vegetation with large solar infrastructures. We conducted an in-depth analysis of land use efficiency and land conversion resulting from solar energy development. Further, our field investigation examined the seasonal microclimatic modifications and the soil properties under solar arrays in a large photovoltaic power plant with different land management practices (bare, vegetated) and compared those to an adjacent undisturbed area. Our analysis of solar facilities shows that there is significant conversion of agricultural land for development of solar facilities and the land use efficiency varies among different prior land use types. Results from the field experiment indicate heterogeneity in soil moisture distribution based on solar panel orientation, and significantly lower total carbon and total nitrogen in the soils from the bare sites compared to those of the vegetated sites. Lastly, the solar panels in the vegetated sites exhibited lower daily maximum temperatures than those in the bare sites. The cooling effect, attributed to the transpiration from the underlying vegetation, may result in higher performance ratio of the solar panels.