Tamil Nadu rooftop solar and net metering calculator
What would rooftop solar do to your Tamil Nadu bill? Enter your use and system size to see the bill with net metering, the PM Surya Ghar subsidy and the payback.
- Tamil Nadu’s own net metering rules
- PM Surya Ghar subsidy built in
- Bill run through the current tariff
Tamil Nadu net metering rules
- Homes can use net metering up to their sanctioned load (TNERC Grid Interactive Solar PV Regulations 2021, reg. 4.2). Source
- Exported units are set off against imported units on each bill, and any extra is carried forward to the next bill. Units still left on 31 March lapse (reg. 6.2). Source
- A network charge applies to all units the system generates (reg. 6.7). Homes up to 10 kW pay 20% of it and larger homes 75% (TNERC Order 8 of 2021). For systems up to 10 kW, generation is taken as the lower of 21% capacity utilisation or the inverter reading. Source
- The LT network charge is ₹1.60 a unit for 2025-26 (TNERC Tariff Order 6 of 2025, para 2.4.2), so a home up to 10 kW pays ₹0.32 a unit of solar generation. Source
- Instead of net metering, homes can choose net feed-in, where exports are paid at ₹3.61 a unit for 1–10 kW. This calculator works out net metering only. Source
Default generation of 100 units per kW a month: the Union Cabinet's PM Surya Ghar note says a 3 kW system 'will be able to generate more than 300 units a month on an average'. Source
PM Surya Ghar central subsidy: ₹30,000 a kW for the first 2 kW and ₹18,000 for the third kW, no more above 3 kW (₹78,000 at most). Grid-connected homes only, domestic-made modules, once per home. MNRE benchmark cost ₹50,000 a kW up to 2 kW and ₹45,000 a kW above. Scheme runs to 31 March 2027. MNRE guidelines
Rooftop solar questions
How does net metering work?
A two-way meter records what you draw from the grid and what your panels send to it. On each bill the units you exported are taken off the units you imported, and you pay for the net units at the normal tariff. What happens to extra units depends on the state: some buy them every month, others carry them forward and settle at the end of the year.
How much does a 1 kW rooftop system generate?
The Union Cabinet’s note on PM Surya Ghar says a 3 kW system makes over 300 units a month on average, about 100 units per kW. MNRE says 1 kW can make 4 to 5.5 units on a clear sunny day. Your roof’s direction, shade and dust change this, so you can edit the figure.
How much is the PM Surya Ghar subsidy?
For homes: ₹30,000 a kW for the first 2 kW and ₹18,000 for the third kW, so ₹78,000 for 3 kW or more. Higher amounts apply in special-category states. The system must be grid-connected and use domestically made modules, and a home can get it only once. The scheme runs until 31 March 2027.
Do I still pay a fixed charge with solar?
Yes. In every state covered here, fixed charges and government levies stay payable whatever your solar credits.