Heating of Urban Environments by Photovoltaic Modules

The paper answers the question if solar modules contribute to additional heating of urban environment compared to conventional mounting areas on buildings. The effective albedo of a module is calculated that contains the optical reflection as well as the electrical energy that is created by the module. The generated heat of the PV module is compared to a scenario without PV installation. Energy input on the module as well as on the environment (mounting area, neighboring buildings) is calculated. The module power output is determined using a bottom-up loss channel model that considers optical, electrical, thermal and geometrical aspects ("SmartCalc.Module" by Fraunhofer ISE). Reflection of the module is obtained from an effective measurement as well as from optical modelling. An energy equilibrium model is used to calculate the generated heat. A sensitivity analysis on mounting conditions and ambient albedos shows that a PV module has a higher thermal impact than a "no PV" scenario. An advantage regarding total heat generation of a PV installation is found only for dark mounting areas. The effective albedo of a PV module is calculated to be 0.24.