Solar savings and payback

Use annual numbers

Start with expected annual generation in kWh. Multiply the part that offsets your bill by the applicable energy value. Add any export value under current state rules. Do not count fixed charges as savings unless they actually fall.

Simple payback = net installed cost ÷ first-year electricity savings. Net cost is the amount you pay after confirmed subsidy. Simple payback does not include financing interest, degradation, inverter replacement or the time value of money.

A transparent 3 kW example

Assume a 3 kW system costs ₹2.10 lakh before subsidy, receives ₹78,000 after meeting all conditions, and produces 4,350 kWh in the first year. If 85% of that energy has an effective value of ₹8 per kWh, first-year savings are about ₹29,600.

Net cost is ₹1.32 lakh. Simple payback is about 4.5 years. This is an illustration, not a promise. A lower tariff, more unused export, shade or delayed subsidy stretches the result.

The five biggest payback levers

1. System price: compare equal equipment and scope.
2. Subsidy eligibility: count it only when the project follows the scheme route.
3. Annual generation: roof direction, shade, weather and losses matter.
4. Energy value: tariff slabs and export settlement matter more than a national average.
5. Use timing: daytime appliances can raise direct self-consumption.

A battery usually increases independence but can lengthen financial payback. Treat backup value separately from bill savings.

Ask for the working behind a savings claim

A vendor should state annual kWh, loss assumptions, tariff used, export treatment and degradation. Reject calculations that multiply panel capacity by 24 hours or promise the same units every day.

Run your bill and roof through our solar cost and savings calculator. Then change the tariff and system size to see which assumption drives the result.