Repository logo

Theses and Dissertations

Permanent URI for this collection

https://hdl.handle.net/10217/100454

Browse

Browsing Theses and Dissertations by Subject "agrivoltaics"

Now showing 1 - 2 of 2
  • Thumbnail Image
    ItemOpen Access
    Evaluating leafy green production in a Colorado rooftop agrivoltaic system
    (Colorado State University. Libraries, 2024) Villa-Ignacio, Armando, author; Bousselot, Jennifer, advisor; Uchanski, Mark, committee member; Sampath, Walajabad, committee member
    Combining green roofs with solar modules can protect plants and produce energy in cities. Growing crops in this system is called rooftop agrivoltaics (RAV) and can complement current urban agriculture efforts. We evaluated a group of five leafy green crops (arugula, kale, lettuce, spinach, and Swiss chard) under different solar modules over two years at two locations. Data measurements were taken for fresh and dry weight (FW, DW) stomatal conductance (SC), plant size at harvest (PSH), and microclimate data. At the Colorado State University Foothills Campus, the treatments included a polycrystalline opaque silicon module, a cadmium telluride (CdTe) frameless opaque module, and a 40% semi-transparent CdTe module. At CSU Spur, there was an opaque module and a bifacial module. Both sites included a full sun control plot. At the Foothills campus, for of the five leafy greens produced higher FW and DW under the 40% semi-transparent modules compared to other treatments and the full sun control, except spinach. Most species also produced larger PSH under the PV module treatments compared to the full sun control. Leafy greens under the module treatments resulted in lower SC, however, lettuce and Swiss chard grown under the semi-transparent module treatment produced higher SC compared to all other treatments. At CSU Spur, plant responses were also species specific with arugula, kale, and lettuce yielding higher FW and DW in full sun. Most leafy greens resulted in lower SC, except for lettuce, which had a higher SC under solar module treatments. Spinach had no difference in FW but lower DW in the opaque treatment compared to the full sun control, and lower SC under both treatments. There was a lower FW between the bifacial treatment and the full sun control in Swiss chard. This research shows that incorporating photovoltaics on rooftop gardens influences the yield and stomatal conductance of select leafy green crops. While FW and DW mostly decreased under the deep shade treatments (opaque module, frameless module, and bifacial module) SC decreased, possibly due to less solar radiation on the leafy greens, reducing water use. Understanding the growth characteristics and growing environment of high value crops like leafy greens will increase understanding of what food crops are suitable for RAV systems.
  • Thumbnail Image
    ItemOpen Access
    Plant growth under photovoltaic arrays of varying transparencies – a study of plant response to light and shadow in agrivoltaic systems
    (Colorado State University. Libraries, 2023) Hickey, Thomas, author; Bousselot, Jennifer, advisor; Uchanski, Mark, advisor; Harrow, Del, committee member
    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.