Impact of Air Mass on Energy Yield Calculation for Bifacial Silicon Heterojunction Photovoltaic Modules in High-Latitude Conditions

Abstract

At high latitudes, bifacial photovoltaics are expected to achieve significant bifacial gain due to the albedo of snow, but irradiance will include a wide range of incident angles and high air mass spectra. We studied the performance of bifacial silicon heterojunction solar modules with increasing angle of incidence and air mass to derive an incidence angle modifier and air mass modifier for short circuit current. We found that the incidence angle modifier remained constant with varied air mass, allowing the incidence angle modifier and air mass modifier to be applied independently. Module correction factors were applied to the SUNLAB's energy yield model, DUET. We demonstrate that the impact of air mass on energy yield increases with latitude and can reach >2.5% on an annual basis for single-axis tracked modules and >2% for fixed latitude-tilt modules in high-latitude locations. This is highly dependent on season, with greater impact in off-summer months, reaching >6.5% monthly air mass impact for a high-latitude location in winter. These results demonstrate that air mass effects are more significant for high-latitude locations, and should be considered in energy yield calculations.