Performance improvement for building integrated photovoltaics in practice: a review

Building integrated photovoltaic (BIPV) technologies are promising and practical for sustainable energy harvesting in buildings. BIPV products are commercially available, but their electrical power outputs in practice are negatively affected by several factors in outdoor environments. Performance improvement of BIPV applications requires mitigation approaches based on an understanding of these factors. A review was, therefore, conducted on this issue in order to providing guidance for practical applications in terms of the selection of proper PV technologies, temperature management, solar irradiation enhancement and avoidance of excessive mechanical strain. First, major types of PV cells used in BIPV applications were comparatively studied in terms of their electrical performances in laboratorial and outdoor environments. Second, temperature elevations were widely reported in outdoor BIPV applications, which may cause efficiency degradation, and the mitigation approaches may include air-flow ventilation, water circulation and utilization of phase change materials. The heat collected from the PV cells may also be further utilized. Third, mechanical strains may be transferred to the integrated PV cells in BIPV applications, and their effects on electrical performance PV cells were also discussed. In addition, the power output of BIPV systems increases with the solar irradiation received by the PV cells, which may be improved in terms of the location, azimuth and tilt of the cells and the transmittance of surface glazing. Suggestions for practical applications and further research opportunities were, therefore, provided.