Determination of economically optimised building integrated photovoltaic systems for utilisation on facades in the tropical climate: A case study of Colombo, Sri Lanka

Building integrated photovoltaics (BIPV) are becoming a viable solution for clean on-site energy production and utilisation to combat the existing energy crisis. In tropical climates, although rooftops are ideal for photovoltaic (PV) module integration, the available area may be insufficient to meet building energy demand due to the recent high-rise nature of urban buildings, causing a requirement for the utilisation of facades. However, the high angle of solar elevation means that facades are unfavourably oriented towards receiving incident solar irradiation. In addition, the issue exists of high solar heat gains into built spaces. This paper proposes a method to utilise horizontally inclined photovoltaic modules integrated on solar shading devices in order to combat these issues of unfavourable inclination and solar heat gains in commercial office buildings in Colombo, Sri Lanka. Various strategies are introduced and evaluated in terms of their inclination angles and the distance between installations. The results are analysed in terms of economic potential in order to determine which strategies are capable of producing the most electricity and reducing building cooling loads for the lowest installation costs. The results show that horizontal inclinations of PV on facades are capable of generating nearly 8% more electricity as a percentage of the building energy consumption when compared with traditional vertical PV facade installations.