Improving performance of solar roof tiles by incorporating phase change material

There is an increasing interest in integrating photovoltaic cells in building components, such as roof tiles. However, conversion efficiency of photovoltaic cells is temperature-dependant and high temperature will reduce the conversion efficiency. This paper studies the performance of mortar roof tiles with integrated solar cells and protective glass. To control the temperature of the solar cells, a phase change material (PCM) at a concentration of 3 wt% was mixed into the mortar roof tiles. The influence of the PCM on the solar-to-electrical power generation is evaluated for the solar roof tiles, and life cycle cost analysis is performed to assess the economic feasibility. It is found that the electrical energy output from the solar roof tiles with PCM is about 4.1% higher than that of the counterpart without PCM in winter days, whereas the corresponding improvement is in the range of 2.2" 4.3% in six summer days. The economical payback time of the solar roof tiles with PCM is found to be 5.7 years including the inverter cost. The use of PCM increases the initial cost of roof tiles by 1.2%; however, considering an overall improvement of 4.1% in the energy output, the payback time is estimated to be three months shorter than that of the counterpart without PCM. The study also confirms that the ambient conditions influence the overall power generation substantially because of the impact on the working temperature of the solar roof tiles.