A systematic review of photovoltaic-green roof systems in different climatic conditions focusing on sustainable cities and societies

Abstract

Photovoltaic (PV) and green roof (GR) both are sustainable approach towards global climatic change and urban heat island (UHI) effect. Integration of these systems result improved benefits for development of environmentally sustained societies. This study examines performance parameters influencing integrated PV-GR system, research gaps at building scale in different climatic conditions. Numerous researches have been conducted to evaluate performance parameters influencing PV-GR system. Most influencing factor affecting the PV-GR performance is height between PV panel and GR followed by coverage of GR on roof and PV-GR ratio. Optimum height between PV-GR is about 30–70 cm as stated in studies referred, height between PV-GR depends on ET cooling mechanism and air flow between them. Plant species is also an important factor influencing the PV-GR performance but due to large variation between results from different species make this factor hard to evaluate. PV-GR system in monsoon humid sub-tropical climate (Cwa) showed significant result in ambient temperature reduction by 9°C and in enhancement of PV efficiency by 4.25% whereas energy saved of 5% was found significant in cold semi-arid climate (Bsk). Performance parameters affecting PV-GR and its benefits needs to have better understanding and precise value, therefore requires in depth research on this system.