Parametric Cold-Frame Agrivoltaic Systems
OSHWA UIDCA000008 Project Website
November 12, 2021
This invention is a parametric open-source smart cold-frame agrivoltaic system (POSCAS). POSCAS is an adapted cold-frame that is normally used for gardening in cold climates as it acts as a small greenhouse for agricultural production. POSCAS is designed to test partially transparent solar photovoltaic (PV) modules targeting the agrivoltaic market. The systems are parametric so they can be adapted for any size of PV module and designed to take advantage of distributed manufacturing. In addition, the thickness of the walls, type of wall insulation, possessing a floor or being directly located on the ground, the tilt angle of the module can all eb controlled by a parametric OpenSCAD script. The script outputs a 3-D printable file (STL) so the frame body can be manufactured from any waste plastic using distributed recycling and additive manufacturing (DRAM). POSCAS can both function as a traditional cold frame but it can also be automated with a temperature sensor, open source Arduino, fan and/or a motor to control air inflow into the greenhouse box. It can also be coupled to any number of other sensors to automate the care of the plants by controlling irrigation and fertilization. The PV module can be used to power the controls or it can be attached to a microinverter to produce power. POSCAS can be placed in an experimental array for testing, agricultural and power production. POSCAS can be easily adapted for any type of partially transparent PV with thin film or crystalline silicon-based modules. The percent transparency of the modules can be tested in a bank of POSCASs by varying the thickness of a thin film PV material, the various forms of optical enhancement and anti-reflection coatings or the density of silicon-based cells in the module. For example, they can be used to optimize Heliene greenhouse solar panels for specific crops. Such Heliene red modules can have different transparencies by adjusting the density of the crystalline-silicon based cells. They are bifacial modules, which contain an energy-producing photovoltaic cells that generates electricity both from the top where the sunlight strikes it and from any reflection coming from underneath, and a red back-sheet. The back sheet transforms the green light spectrum into red before reaching the plants in the POSCAS below, while at the same time reflecting it back to the photovoltaic cell, which turns it into electricity that can be used in the greenhouse. The active materials that are in the back sheet can also be tested by the POSCAS (e.g. testing the density, size and chemical makeup of nanoparticles responsible for the solar light spectral shifting). All of these variables can be used to identify ideal PV designs for a given agricultural crop. This includes experimentally verifying the albedo from the crops and their impact on the different types of partially-transparent bifacial PV modules.
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