Performance level criteria for semi-transparent photovoltaic windows based on dye-sensitized solar cells

Since the discovery of the photovoltaic (PV) effect in the 19th century, various PV windows have been developed to improve the energy performance of a building and expand the supply of renewable energy. Dye-sensitized solar cells (DSSCs) have attracted attention as promising alternatives to conventional silicon solar cells because of their transparency and aesthetic value. This study aims to analyze the effect of DSSC windows on the building environment and energy performance and build a database to help architects select appropriate DSSC windows for future zero-energy buildings (ZEBs). We use Design Builder, a building energy analysis program, to evaluate indoor illuminance, indoor temperature, cooling and heating energy, lighting energy, and power generation. Our prototype DSSC windows exhibit an improved heat transmission rate (i.e., U-value) but lower visible-light transmission (VLT) than low-emissivity glazing windows; thus, they decrease the heating energy and increase the cooling and lighting energy. We predict that DSSC windows meeting the criteria of 13% power conversion efficiency (PCE) and 30% VLT will achieve energy savings of 4861.44 kWh/yr. PV windows with over 50% VLT with any PCE can be beneficial to net zero-energy and net energy-plus buildings.