Plant growth under photovoltaic arrays of varying transparencies – a study of plant response to light and shadow in agrivoltaic systems
Date
2023
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Abstract
Amidst the rising global pressures put on the interdependent systems in the food, energy, and water nexus, this document highlights the potential for systems-based solutions at the intersection of food cultivation, ecosystem services, and energy production in urban and rural environments. Agrivoltaics (APV) is a land-use model that enables simultaneous cultivation of food crops and electricity generation on the same plot of land. Agrivoltaic systems integrate solar photovoltaic (PV) energy generation with agricultural operations, maximizing the utilization of solar energy. This approach has gained significant research interest in the United States with scalable implementation is on the horizon. Research efforts at Colorado State University (CSU) aim to advance the understanding of plant responses to various shade conditions under PV arrays, benefiting stakeholders in agriculture, solar energy industries, policymakers, and governmental agencies. In particular, agrivoltaic research conducted at CSU's Horticulture and Landscape Architecture (HLA) department has focused on open field specialty crops and native pollinator plant species while documenting the overarching light and temperature growing environment. A replicated 2-year crop trial was conducted at the open field test site, comparing crop yield and growing conditions under three different PV module types with varying transparencies to traditional full sun production. Statistical analysis revealed a reduction in squash yield directly under the PV panels while no significant differences in yield for bell peppers, jalapeno peppers, lettuce and tomatoes growing north and south of the arrays. In a separate study, a simulated green roof structure was constructed around an existing PV array at CSU's Foothills Campus to explore the feasibility of rooftop agrivoltaics. A one-year study of six native pollinator plant species was conducted to assess differences in establishment, survivability, growth index, and growing conditions between full sun and PV shade environments. Overall, there were no statistically significant differences in mean Plant Growth Index (PGI) throughout the establishment season, however, notable variations in overwinter survivability were observed. In both studies the PV modules moderated the environment, resulting in lower maximum daytime ambient temperatures and even greater reduction in soil temperature throughout the growing season. Light levels are reduced under all PV module types with the least reduction under semi-transparent modules. Variations in growing conditions in these APV systems indicate the need for further research to optimize PV systems in order to maximize energy production and plant vitality.
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Subject
photovoltaics
agrivoltaics