Calculator

Solar Battery Calculator

Check whether a battery makes sense on top of your PV system. The calculator estimates self-consumption with battery, added annual battery value and battery payback.

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The solar battery calculator does not evaluate the whole PV system, but the battery as an additional investment. It shows how much PV surplus the battery can roughly shift into self-consumption and whether that added value can justify the battery cost.

Display currencyChoose the currency symbol for entered amounts and results. No exchange-rate conversion is applied.

Annual PV yield (kWh)

If you do not know annual yield: system size in kWp × roughly 900–1,000 kWh/kWp/year as a first estimate.

Annual household electricity use (kWh)

You can find this number on your electricity bill. It limits how much solar power can realistically be used on site.

Battery capacity (kWh)

Usable battery capacity. The calculator estimates how much PV surplus can be shifted for later self-use per year.

Assumed full cycles per year

An explicit scenario assumption instead of a hidden constant. For a real quote, use the cycle estimate from a load-profile simulation where possible.

Battery round-trip efficiency (%)

Accounts for charging and discharging losses. 90% is a simplified model assumption.

Battery cost ($)

Additional cost for the battery only, including installation.

Electricity price ($/kWh)

Annual battery operating cost (% of investment)

Allowance for maintenance, service or recurring system cost. Enter 0% to omit it deliberately.

Feed-in tariff ($/kWh)

Assumed battery lifetime (years)

Planning assumption for economics. The shorter the lifetime, the harder it is for the battery to pay off.

FAQ

FAQ about Solar Battery Calculator

Does a solar battery always pay off?

No. It pays off economically only if the additional self-consumption offsets the extra cost over its lifetime.

What battery size makes sense?

Battery size should match PV surplus and evening or night demand. An oversized battery is used less often and can pay back more slowly.

Why does the feed-in tariff matter?

Stored electricity would often otherwise have been exported. The economic value is therefore electricity price minus forgone feed-in tariff.

Is battery payback certain?

No. It is a rough estimate. Load profile, weather, efficiency, ageing and electricity prices can materially change the result.

Does a battery increase autonomy?

Usually yes. But economics and autonomy are not the same: more independence can be valuable even when financial return is lower.