In a solar rooftop system, the solar panels are installed in the roof of any residential, commercial, institutional and industrial buildings. This can be of two types:
The area required by a rooftop PV plant depends on the extent of shade-free space available and solar panel efficiency.
A solar PV system typically requires 100 square feet (about 10 sq.m) of shade free roof area per kW of capacity at current crystalline panel efficiency levels.
In grid connected rooftop or small SPV system, the DC power generated from SPV panel is converted to AC power using power conditioning unit and is fed to the grid either of 33 kV/11 kV three phase lines or of 440/220 Volt three/single phase line depending on the capacity of the system installed at institution / commercial establishment or residential complex and the regulatory framework specified for respective States.
These systems generate power during the day time which is utilized fully by powering captive loads and feed excess power to the grid as long as grid is available. In case, where solar power is not sufficient due to cloud cover etc., the captive loads are served by drawing power from the grid.
The size of the system you need depends on several factors: how much electricity you use, how much money are you willing to invest and what is the size of your roof. You should also consider if you want solar energy to meet all your energy needs or just a portion of them.
Such rooftop systems can be installed at the roofs of residential and commercial complex, housing societies, community centers, government organizations, private institutions, etc.
Most manufacturers give 20-25-year warranty but If solar panels are installed and maintained properly, you can expect them to last and produce good amount of electricity for up to 35-40 years.
In case the grid fails, the solar power has to be fully utilized or stopped immediately feeding to the grid so as to safe-guard any grid person/technician from getting shock (electrocuted) while working on the grid for maintenance etc. This feature is termed as ‘Islanding Protection’.
Warranties Solar panels typically have 10 years’ manufacturer’s warranty with additional performance warranty of 25 years. Other system components (inverters, mounting structures, batteries, junction boxes, etc.) typically have 1 -5 years’ manufacturer’s warranty.
There are various solar policies that incentivize rooftop solar in India. Central government schemes include 80% accelerated depreciation, capital subsidy of 30% and more based on location, and Renewable Energy Certificates (RECs). Some states have further incentives under their own solar policies. Permissions primarily deal with ensuring the grid isn’t congested by receiving approval from local power distribution authorities.