Influence analysis of photovoltaic rooftops on urban thermal environment based on orthogonal test method

Understanding the influence of photovoltaic(PV) rooftops on the urban thermal environment will help promote the rational application of urban PV and facilitate the construction of low-carbon cities. A heat transfer model of PV rooftops is established and verified with the help of the weather research and forecasting(WRF) model and orthogonal test method. Taking the outdoor air temperature, potential temperature variation amplitude, and roof heat flux as the evaluation indexes, the influence of three factors, namely surface albedo, installation form, and laying ratio of PV modules, on the urban thermal environment is analysed. The results show that these three factors have a significant influence on the outdoor air temperature and roof heat flux, and the influence degree from large to small is the installation form, laying ratio, and surface albedo of PV modules. Under the test conditions, the optimal combination is as follows: adhesive installation, laying ratio of 0.6 (civil buildings) and 0.9 (industrial buildings), and surface albedo of 0.3. Compared to the scenario without PV installations, this combination can reduce the outdoor air temperature by 0.5 to 0.6 ℃ during daytime and 0.3 ℃ at night, respectively, and mitigate the urban heat island effect by 0.2 ℃.