Solar + battery vs solar only
What could a 7.5 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£252 estimated annual value
£4,375 illustrative extra battery cost · 1,350 kWh solar shifted · 525 kWh tariff shifted
Sensitivity
| Scenario | Solar shifted | Tariff shifted | Import/export | Cheap rate | Annual value | Simple payback |
|---|---|---|---|---|---|---|
| Cautious | 945 kWh | 368 kWh | 24/15p | 10p | £123/yr | 35.6 yrs |
| Base | 1,350 kWh | 525 kWh | 28/15p | 8p | £252/yr | 17.3 yrs |
| High-use | 1,620 kWh | 630 kWh | 32/10p | 7p | £463/yr | 9.5 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.