Solar Energy (Photovolatics)
Aim/Objective: This 3-year project aims to increase the performance and resilience of PV systems deployed in regions of the US that regularly experience below-freezing precipitation in order to increase the efficiency of performance and thus expand solar capacity in those areas. Specifically, we aim to: 1. Quantify snow losses across multiple sites and technologies, 2. Identify snow- and ice-provoked reliability issues, 3. Identify topological and component features that enhance or inhibit snow shedding, and 4.Develop advanced snow-loss models.
Methods: Our multi-institutional team has begun to identify and quantify the multiple factors that contribute to improved system performance at northern latitudes, where snow accumulation on the ground and on solar panels can be significant. Our methods include: 1. Camera imaging of installed systems (also synched with power, irradiance and meteorological data) to measure snow-shedding rates under different variables (framed vs frameless; coated and uncoated glass and frames; orientation and tilt angle) and quantify associated energy yields, 2. Performance analysis of bifacial modules at different tilt angles and on a dual-axis tracker based on high-resolution DC voltage and current measurements; also tracker-error monitors, 3. EL-imaging of multiple modules types to identify patterns of damage likely attributable to ice buildup, snow loading, tracker stress under extreme cold conditions and shunt formation induced by partial shading (monolithic CIGS modules), and 4. Laboratory characterization in a temperature-controlled room of module glass and coatings for their ice-phobic properties.
Results: Our results to-date show: 1. Certain module architectures significantly outperform others, most notably frameless modules, suggesting the frame is a significant impediment to snow shedding and therefore needs to be redesigned, 2. Bifacial modules, especially those mounted on a dual-axis tracker, deliver significantly more DC energy than adjacent mono-facial modules, with bifacial gain during the winter months as high as 91 percent and as high as 13 percent in non-snowy months. Our data also suggests that vertically mounted bifacial modules may provide a performance advantage over latitude-tilt modules, and 3. Characterization of coatings for icephobicity and optical transmissivity are helping define an optimal set of properties for ice-phobic PV coatings, with expectation that field validation next winter will show a significant reduction in snow losses for the top-performing coatings, which in turn will create new market opportunities for anti-ice PV coatings.
Conclusions: Our pioneering multi-faceted investigation into system performance in wintry climates is generating data that will inform new system designs, lowering LCOE, increasing resource availability in the aftermath of extreme weather events, and resulting in greater system efficiency.