A simulation model has been developed to investigate the thermal and electrical energy performance of photovoltaic roofs (PV roofs).Direct numerical simulations of heat transfer and energy conversion of PV roofs are made by introducing a cumulative variable, which can simplify the heat transfer calculation problems. The cumulative variable is inverted to represent the roof surface temperature instead of real surface temperature so that it is easier to deal with thermal radiation heat transfer between the two-layer surfaces of the ventilated PV roofs. Natural ventilation heat transfer in the ventilation gap takes away a large amount of heat, which reduces the cooling load of the buildings. The cooling load reduction, the ventilation gap ratio, and the roof inclination angle are discussed in this paper. It is found that the cooling load component through a PV roof is about 35% compared with the load of a conventional roof.

Units: SI