Critical factors affecting retrofitted roof-mounted photovoltaic arrays: Malaysian case study

This paper presents the findings of a field pilot study to investigate the critical factors that affect retrofitted roof-mounted photovoltaic (PV) arrays in terms of their contributions to the operating cell temperature in Malaysian climate. The critical factors investigated in this study are the mounting roof materials, mounting heights, solar radiation levels and types of PV modules. As with all PV technologies, the power production is a negative function of temperature, thus knowledge of the optimum mounting parameters will directly affect output. In this work, mono-crystalline and poly-crystalline PV modules were each installed on two mock-up roofs with roofing material of concrete tiles and metal deck. The air gap between the roof surfaces and the PV modules was varied at 0 cm 10 cm and 20 cm. Data for PV module cell temperature, ambient air temperature, and solar irradiance were concurrently logged at 5-minute intervals using an automated datalogger. Results were analysed to determine the temperature difference between PV module cell temperature and ambient temperature for each irradiance level and lastly to determine the relation between the temperatures for each height of air gap. Finally the Ross coefficient definition was used as a test to determine the type of ventilation that was used in this research.