A 1 kw rooftop system generally requires 10 sq. metres (100 square feet) of flat, shadow-free area (preferably south-facing). Actual sizing, however, depends also on local factors of solar radiation and weather conditions and shape of the roof.

It depends on the consumption cycle. If the consumption cycle matches with the generation cycle then battery may not be required. Also, in case of net metering, excess power will be credited in the bill so no battery is required.

Solar panels work just fine in ambient light and will produce significant energy in the fog or on overcast days. In bad weather, the production may not be 100% but they will produce power. On cloudy days, they may produce 60% of the required output.

Solar panels manufacturer’s warranty is 25 years. So, broadly life of solar rooftop is 25 years. However, it does function after 25 years with 80% output.

They rarely require any maintenance or cleaning, plus they have warranty of minimum 25 years. All it requires is to wash panels once every 15-20 days with a cloth.