Effect of distributed photovoltaic power station on cooling load induced by roof for sunny day in summer

The distributed photovoltaic power station installed on roof has been widely adopted in city which provides electricity and cuts the energy consumption of building. However, the station also changes the original condition of roof, affects the heat transfer between roof and outside and the conductive heat flux through roof, then the cooling load induced by conductive heat flux. Experiments were carried out on high bracket installation and low bracket installation on flat roof in July and August. The temperatures of photovoltaic module, original roof and shadowed roof were measured to calculate the conductive heat flux through roof. Modification was made for radiation time series method to calculate the cooling load induced by calculated conductive heat flux through roof. For high bracket installation, the cooling load of shadowed roof reduces about 27.5% in whole day, and reduces about 37.4% between 08.00 and 17.00 compared to original roof for sunny day. For low bracket installation, the cooling load of shadowed roof reduces about 18.8% in whole day, and reduces about 27.2% between 08.00 and 17.00 compared to original roof for sunny day. The cooling load of whole roof with distributed PV station also relates to roof utility. Small cooling load can be obtained with big roof utility under same installation method. And the cooling load of roof is lower with high bracket PV station than low bracket PV station with same roof utility in sunny day.