A house with a south-facing roof has photovoltaic panels on the roof. The photovoltaic panels have an efficiency of 10.3 % and occupy an area with dimensions 3.35 m by 8.55 m. The average solar radiation incident on the panels is 305 W/m2, averaged over all conditions for a year. How many kilowatt hours of electricity will the solar panels generate in 20 days?
area is 28.64 m²
incident power is 305 W/m² x 28.64 m² = 8740 watts
output power = 8740 watts x 0.103 = 900 watts
900 watts x 24 hr/day x 20 days = 432000 watt-hour / day or 432 kW-hour / day