3D Rooftop Photovoltaic Potential Calculation Using GIS Techniques: A Case Study of F-11 Sector Islamabad

Pakistan is swiftly growing household electricity consumption country. There is approximately 9% increase in domestic consumption while the country is presently facing energy shortfalls. There is a need of considering energy mix due to increase in fossil energy prices, increased energy demand and unstable supply of electricity. Pakistan has great potential for solar renewable energy. Daily average value of received in solation is 5.4 kWh/m²/day. Rooftop photovoltaic technology is environment friendly and can be implemented by utilizing building rooftops without reserving any open space. F-11 sector of Islamabad, capital territory of Pakistan, was selected as study area for rooftop photovoltaic energy calculations. A GIS overlay analysis based methodology was developed for selecting suitable rooftops for photovoltaic system installation using high resolution Digital Surface Model (DSM), topographic factors and climate factors as input. Calculation of received solar radiation for complex urban environments is crucial as received amount of radiation varies with shadow by adjacent builds and trees so 3D shadow analysis of study area was done using tree growth model in Ecotect Analyst. Results showed, average received in solation is 1.65 MWh/m²/year with 4,359 annual peak solar hours and correlation coefficient is 0.94 between Marksim model base in solation and derived in solation from solar analyst tool. There is 0.4 km² rooftops are suitable for photovoltaic system out of 0.6 km² built-up area of sector and 90% of built-up area received 20-30 kW/m²/month in solation in June. Shadow analysis showed that amount of received solar radiation will reduce 5% in next 10 years and 10% in next 20 years.