Solar + battery vs solar only
What could a 12 kWh battery add to solar?
The model separates the value of extra solar self-use from optional tariff shifting. That avoids treating exported solar as if it had no value.
Illustrative base case£404 estimated annual value
£5,500 illustrative extra battery cost · 2,160 kWh solar shifted · 840 kWh tariff shifted
Sensitivity
| Scenario | Solar shifted | Tariff shifted | Import/export | Cheap rate | Annual value | Simple payback |
|---|---|---|---|---|---|---|
| Cautious | 1,512 kWh | 588 kWh | 24/15p | 10p | £197/yr | 28.0 yrs |
| Base | 2,160 kWh | 840 kWh | 28/15p | 8p | £404/yr | 13.6 yrs |
| High-use | 2,592 kWh | 1,008 kWh | 32/10p | 7p | £740/yr | 7.4 yrs |
This is a planning comparison, not a recommendation for a particular battery size. Actual half-hourly load, battery power, usable capacity, export tariff and degradation can change the result materially.