Residential housing societies in India have one more reason to ditch diesel generators (DGs) and adopt rooftop solar for power backup. A new policy paper titled Solar Rooftop: Replacing Diesel Generators in Residential Societies by the Centre for Science and Environment (CSE) analysed five housing societies in India and found that it is not just easy to replace polluting diesel generators with the solar power systems, but is a big cost saver as well. In all the residential societies that CSE studied and analysed, the cost of power from solar rooftop with battery backup was found to be about half the cost of power generated by DG sets (if only the diesel cost and maintenance cost of DG sets are considered). This alone should make residential societies move away from the extremely polluting diesel generators and adopt solar rooftops to meet their power backup needs, said Chandra Bhushan, deputy director general, CSE.