The performance of four domestic rooftop 7.8 kW − PV in the Kingdom of Bahrain: toward low building emission

Abstract

This paper reports the performance of four domestic houses at different locations in Bahrain, each have 7.8 kW of PV on the roof, and all panels are tilted at 12°, but the azimuth of the panels (orientation) in these houses varies slightly from south (±10°); depending on roof space availability and building surroundings. The data of year 2019 have been used because all these domestic houses were monitored, maintained, and cleaned by an assigned company from the government. The annual solar electricity generated was 11,329 kWh, 11,448 kWh, 10,978 kWh, and 9995 kWh for houses # 4, # 2, #1, and # 3, respectively. The annual Specific Yield (SY) obtained was 1468 kWh/kW, 1452 kWh/kW, 1407 kWh/kW and 1254 kWh/kW for houses # 2, #4, # 1, and # 3, respectively; this makes the daily average SY equals to 4.02 kWh/kW, 3.98 kWh/kW, 3.85 kWh/kW, and 3.43 kWh/kW, respectively. The average performance ratio (PR) of each PV system were found to range from 75.1% to 65.6%. The PV system performs better in house #4 due to its azimuth PV panels' angle (orientation) which is closest to the south direction. A polynomial equation is established, relating the month number (X) and the monthly average of monthly solar electricity generated as well as the monthly specific yield (Y). This work shows that installing a 7.8 kWp of PV on the roof of all residential building in Bahrain will reduce the total CO2 emission in Bahrain by 39.0% (4.637 tons) per year, saving 38,567 ft3 of natural gas. This is a step towards low-carbon building; in an attempt to make Bahrain a zero carbon by 2060.