Effect of reflective coating on thermal and electrical performances of solar roof tiles

Compared to solar panels, the current adoption rate of building integrated photovoltaic (BIPV) systems in Australia is relatively low owing to their complex design, fluctuation in efficiency during operation and high cost. The efficiency of the BIPV system drops significantly with the increase of module temperature beyond 25 degrees C. To stabilise the system temperature during operation and reduce the complexity of integration of a cooling system, reflective coating (RC) has been introduced in the present work. The effect of reflective coating on the electrical and thermal performances of a BIPV system, specifically solar roof tiles (SRTs), has been investigated. Several types of RCs and their application methods have been tested to optimise their performance. In the laboratory test, it was found that the RC could reduce the surface temperature by 11 degrees C, leading to an electrical efficiency improvement of 6.61%; while in the natural environment test, the observed temperature reduction was 10 degrees C, providing an electrical efficiency improvement of 6%. The internal temperature of an enclosed polystyrene test chamber placed under the SRTs during testing was also monitored. It was found that a reduction in the internal test chamber temperature of 18.7% could be achieved with RC, indicating a positive influence in lowering the interference between indoor and outdoor environments. However, RC beneath the monocrystalline silicon solar cells did not make an obvious contribution to the temperature reduction.