According to our calculations, the average-sized roof can produce about 22,400 kilowatt-hours (kWh) of solar electricity annually—about double the average U. Each type offers distinct advantages and drawbacks that can affect overall power generation. Recent studies show that the average efficiency of modern rooftop solar panels hovers between 15% and 22%. But also, the world isn't perfect. It'll likely still. A rooftop solar power system, or rooftop PV system, is a photovoltaic (PV) system that has its electricity -generating solar panels mounted on the rooftop of a residential or commercial building or structure. The various components of such a system include photovoltaic modules, mounting. Estimates the energy production of grid-connected photovoltaic (PV) energy systems throughout the world. It allows homeowners, small building owners, installers and manufacturers to easily develop estimates of the performance of potential PV installations.