Operation behaviour of roof installed photovoltaic modules

Photovoltaic energy in the building environment is a very interesting application. On existing building roofs, the installation of photovoltaic generators is a common mounting configuration. It is important to assess and predict the operational behaviour regarding energy output, power rating and critical operation limits of such modules. This contribution summarizes some detailed experimental and theoretical examinations regarding the operational behaviour of roof-installed PV power system modules. Reverse ventilation was analyzed on the basis of buoyancy forces and pressure loss mechanisms. The correlations were transferred to a computer program PVROOF and verified in the ZSW test site, Germany. Experimental and simulation results regarding the influence of roof cover and the distance between the roof and the PV module are shown. With such results, roof-mounted PV power system installations can be optimized with respect to electrical and thermal energy output.