Solar + battery vs solar only
What could a 30 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£1,010 estimated annual value
£10,000 illustrative extra battery cost · 5,400 kWh solar shifted · 2,100 kWh tariff shifted
Sensitivity
| Scenario | Solar shifted | Tariff shifted | Import/export | Cheap rate | Annual value | Simple payback |
|---|---|---|---|---|---|---|
| Cautious | 3,780 kWh | 1,470 kWh | 24/15p | 10p | £491/yr | 20.4 yrs |
| Base | 5,400 kWh | 2,100 kWh | 28/15p | 8p | £1,010/yr | 9.9 yrs |
| High-use | 6,480 kWh | 2,520 kWh | 32/10p | 7p | £1,850/yr | 5.4 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.