Solar and home battery calculator

Enter system size, annual yield per installed kWp, household consumption and a direct self-consumption share. Set your own installation costs, import price and export payment. These inputs describe a scenario; they are not a quotation or a site survey.

Formula

Annual generation = installed kWp × yield in kWh/kWp. Direct use is limited by household demand. Battery delivery is limited by surplus generation, capacity × cycles × round-trip efficiency, and remaining household demand. Savings value avoided imports and remaining exports.

Worked example

A 4 kWp array with an assumed yield of 1,000 kWh/kWp generates 4,000 kWh annually. At 40% direct self-consumption, 1,600 kWh supplies the home before adding a battery, provided demand is sufficient.

What the result means

Coverage is self-consumed energy divided by household consumption. Simple payback divides investment by annual savings. Battery payback uses only the extra savings attributable to storage, after the export income forgone.

Electricity price · India

₹8.00/kWh is an illustrative input, not an India-wide average or an official electricity tariff. Replace it with the applicable rate for your state, DISCOM, consumer category and consumption slab.

Last reviewed: 9 September 2026

Electricity duty, fuel or power purchase adjustments, fixed charges and subsidies depend on the applicable state and DISCOM rules. No national tax percentage or subsidy is assumed. Slab thresholds, sanctioned-load charges and time-of-day tariffs are not automatically modelled.

Assumptions and limits

Annual totals cannot model hourly matching, winter shortages, roof shading, degradation, financing or future tariffs. Battery capacity is treated as energy charged per cycle.

Questions answered

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