Design Issues and Contribution to Building Energy of Photovoltaic Roof

Building-integrated photovoltaics (BIPV) is a relatively recent new application of photovoltaic (PV) energy technologies whose energy output is affected by many design-related factors including PV module technologies, installation orientation, tilt and shadow range of solar panels. The shading analysis of a residential house's PV roof in Beijing was conducted by using building analysis program Autodesk Ecotect 2010. Analysis result shows that there is no shadow on the PV roof from 9a.m to 4p.m in winter solstice when the solar altitude angle reaches minimum, which ensures almost no shading losses for the PV modules over the year. The differences in monthly energy output were compared in the case of different installation tilt of solar panels and PV module technologies. Finally, the contribution to the building energy of the PV roof was discussed. The results show that appropriate design and selection of PV modules can compensate for the energy requirements for building heating and cooling to some extent.