Vegetable crop growth under photovoltaic (PV) modules of varying transparencies

The present study summarizes two growing seasons (2020-2021) of microclimate characterization and vegetable crop growth in an agrivoltaics system in northern Colorado, USA. The replicated experiment evaluated three module transparency types (opaque silicon [0 % transparent], bifacial silicon [∼5 % transparent], and semi-transparent cadmium telluride [40 % transparent]) plus a full sun control, and four vegetable crop species (summer squash, peppers, tomatoes, and lettuce). Air temperature under the modules in July was approximately 0.5 °C cooler than in the full sun. Soil temperature (2.5 cm depth) maximum differences were more pronounced and were 5.8 °C, 9 °C, and 14.4 °C cooler under bifacial, semi-transparent, and opaque silicon, respectively. For summer squash growing directly under the solar modules, yield was significantly reduced under each of the module transparency types. However, there was no statistically significant yield reduction for peppers, tomatoes, and lettuce indicating their suitability in an agrivoltaics system. The numerical yield of most crops increased as the transparency of the solar modules increased, which could be the focus on future work.