How it is worked out
Each kW of rooftop solar produces about 4 units a day in most of India, or roughly 1,400–1,500 units a year. The suggested size covers your monthly use.
Under PM Surya Ghar: Muft Bijli Yojana, homes get a central subsidy of ₹30,000 per kW for the first 2 kW and ₹18,000 for the third kW, so up to ₹78,000 for 3 kW or more. Some states add their own subsidy. You apply on the national portal and must use a registered vendor.
Savings assume net metering, so units you export are set off against units you import. Panels lose about 0.5% of output a year, which this estimate allows for over 25 years.
Frequently asked questions
How much roof space do I need?
About 80–100 sq ft of shade-free roof per kW.
Does solar work in the monsoon?
Output drops on cloudy days, but a full year averages out to the units per day you enter.
Do I need batteries?
Not with an on-grid net-metered system. Batteries add cost and are needed only if you want power during cuts.
Sources
- PM Surya Ghar ↗ – national portal and subsidy rules