Impact of Rooftop PV Shading on Net Electrical Energy Demand of Buildings in Pakistan

Abstract

This work performs a quantitative assessment of the impact of rooftop PV installation on building’s net energy demand using model of roof structure and steady state thermal simulations. For this purpose, roof structure typically used in Faisalabad, Pakistan is modeled with and without the shading effect due to a 395 W commercial rooftop PV setup. The simulated parameters include the impact of PV module’s dimensions, mounting position/angle alongside roof size and ambient conditions on heat load of air-conditioning system to maintain a temperature of 25 °C within building’s top floor. During the daylight hours of July, the heat load added by the roof on average reduces from 150.87 BTU/h/m2 without PV to 118.16 BTU/h/m2 with PV structure. This 20.05% reduction in energy demand has been achieved with July’s maximum daytime solar and infrared irradiances of 792.2 W/m2 and 466 W/m2 recorded at an average ambient temperature of 35.5 °C and wind speed of 2.75 m/s. This study provides valuable data on optimization of roof layer structure during building’s construction in anticipation of PV system installation at a later stage. Also developed techniques/methods to reduce building’s energy budget due to PV installation, can be valuable input for construction industry as well.