Your home
A few quick details so the estimate reflects your household, not a generic average
Flat / small home
Average home
Large home
You'll get the most accurate result with a recent electricity bill to hand. If you're not sure, leave the defaults below — they're typical UK values.
Compare your scenarios
Each one builds on the last — see exactly where the extra value comes from
Solar panels only
Solar + battery
Solar + battery + smart tariff
Cumulative savings over 25 years
Includes your assumed 4%/yr electricity price rise
Monthly generation profile
Estimated solar output across the year for your system size
What makes up your savings
| Component | Solar only | + Battery | + Smart tariff |
|---|---|---|---|
| Grid electricity avoided | £0 | £0 | £0 |
| SEG export income | £0 | £0 | £0 |
| Off-peak battery arbitrage | £0 | £0 | £0 |
| EV charging saving | £0 | £0 | £0 |
| Total annual saving | £0 | £0 | £0 |
Energy self-sufficiency
How much of your annual electricity comes from your own roof
How we calculated this
- Solar generation: – kWh/yr, based on – kWp at – kWh/kWp (your region × roof direction)
- Self-consumption: –% of generation used on-site in year 1, reflecting your daytime occupancy
- Export rate: –p/kWh for remaining generation exported under SEG
- Battery adds: shifts an additional ~30–35 percentage points of generation from export to self-use
- Smart tariff bonus: off-peak arbitrage plus a premium export rate, modelled at roughly £150–300/yr depending on system size
- Price rise assumption: –%/yr, compounded over 25 years
- Panel degradation: 0.5%/yr efficiency loss built into every projection
- This calculator does not show installation costs — that depends on your specific roof and system, and needs a proper site survey.
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This calculator provides estimates only. Results depend on your specific property, location, consumption habits, tariff choice and equipment. Always obtain professional quotes and an on-site survey before making investment decisions. Data reference points: Ofgem price cap, typical UK regional solar yields, and industry-standard SEG rate ranges — review and update these periodically.