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Co-locating solar photovoltaics (PV) with agriculture or natural vegetation could provide a sustainable solution to meeting growing food and energy demands, particularly considering the recent concerns of solar PV encroaching on agricultural and natural areas. However, the identification and quantification of the mutual interactions between the solar panels and the underlying soil-vegetation system are scarce. This is a critical research gap, as understanding these feedbacks are important for minimizing environmental impacts and for designing resource conserving and climate-resilient food-energy production systems. We monitored the microclimate, soil moisture distribution, and soil properties at three utility-scale solar facilities (MN, USA) with different site management practices, with an emphasis on verifying previously hypothesized vegetation-driven cooling of solar panels. The microclimatic variables (air and soil temperature, relative humidity, wind speed and direction) and soil moisture were significantly different between the PV site with bare soil (bare-PV) and vegetated PV (veg.-PV) site. Compared to the bare-PV site, the veg.-PV site also had significantly higher levels of total soil carbon and total soil nitrogen, as well as higher humidity and lower air and soil temperatures. Further, soil moisture heterogeneity created by the solar panels was homogenized by vegetation at the veg.-PV sites. However, we found no significant panel cooling or increase in electricity output that could be linked to co-location of the panels with vegetation in these facilities. We link these outcomes to the background climatic conditions (not water limited system) and soil moisture conditions. In regions with persistent high soil moisture (more frequent rainfall events) soil evaporation from wet bare soil may be comparable or even higher than from a vegetated surface. Thus, the cooling effects of vegetation on solar panels are not universal but rather site-specific depending on the background climate and soil properties. Regardless, the other co-benefits of maintaining vegetation at solar PV sites including the impacts on microclimate, soil moisture distribution, and soil quality support the case for solar PV–vegetation co-located systems.
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Managed sheep grazing can improve soil quality and carbon sequestration at solar photovoltaic sites
Solar energy development is land intensive and recent studies have demonstrated the negative impacts of large-scale solar deployment on vegetation and soil. Co-locating vegetation with managed grazing on utility scale solar PV sites could provide a sustainable solution to meeting the growing food and energy demands, along with providing several co-benefits. However, the impacts of introducing grazing on soil properties at vegetated solar PV sites are not well understood. To address this knowledge gap, we investigated the impacts of episodic sheep grazing on soil properties (micro and macro nutrients, carbon storage, soil grain size distribution) at six commercial solar PV sites (MN, USA) and compared that to undisturbed control sites. Results indicate that implementing managed sheep grazing significantly increased total carbon storage (10-80%) and available nutrients, and the magnitude of change correlated with the grazing frequency (1-5 years) at the study sites. Furthermore, it was found that sites that experienced consecutive annual grazing treatments benefitted more than intermittently grazed sites. The findings will help in designing resource conserving integrated solar energy and food/fodder systems, along with increasing soil quality and carbon sequestration.
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- Award ID(s):
- 1943969
- PAR ID:
- 10341233
- Date Published:
- Journal Name:
- AGU 2021 Fall Meeting
- Format(s):
- Medium: X
- Sponsoring Org:
- National Science Foundation
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- Free Publicly Accessible Full Text
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Accepted Manuscript1.0
- Conference Paper:
- https://doi.org/10.1002/essoar.10510141.1
