Net energy and cost benefit of transparent organic solar cells in building-integrated applications

Transparent photovoltaics is a new technology that can be used in buildings applications to simultaneously save energy and produce electricity. This study evaluates the potential of transparent photovoltaic (TPV) in window and skylight applications for four cities in the United States: Detroit, Los Angeles, Phoenix and Honolulu. Building energy demand simulation, photovoltaic generation, and life cycle assessment (LCA) are combined to evaluate the net energy benefit (NEB). The use of TPV on windows is evaluated for both new windows, for which the solar cell is deposited in the interior surface of the glass pane, and for the refurbishment of existing windows, for which plastic encapsulated solar cells are placed on the interior surface of existing windows. The NEB was found to be positive for all scenarios considered, and the cradle to gate energy to manufacture a transparent organic photovoltaic module was found to be negligible. The NEB was used to calculate the energy return on investment (EROI) and the energy payback time (EPBT). Both were found to be either better or comparable to other photovoltaic technologies. For glass modules, the best EROI was 102 in Phoenix for window and 208 in Honolulu for skylights. The EPBT varied from 51 days to 1.1 years, depending on the location and type of module. The use of transparent photovoltaics in the US was found to have both environmental and cost benefits due to the combined reduction in building energy consumption and electricity production.