Interactive Calculator

Solar + Battery Savings Calculator

Model your annual savings from solar panels with or without battery storage. Uses current UK electricity prices and export tariff rates to give you realistic estimates.

Aerial view of a house roof fitted with solar panels — A typical 4 kWp array needs 20–28 m² of unshaded roof. East–west splits give flatter, more usable generation than pure south.

Last updated: April 2026 · Reflects Ofgem Q2 2026 price cap

1 Your electricity usage

Annual electricity usage

The average UK home uses about 2,700 kWh/year. Check your bill or annual statement.

kWh per year

Your electricity rate

The Ofgem Q3 2026 cap (1 Jul–30 Sep) is 26.11p/kWh. Check your tariff for your actual rate.

pence per kWh

2 Solar panel system

System size

A typical 3-bed home fits a 3.5–4 kW system. Larger roofs can fit 5–6 kW+.

1 kW4.0 kW12 kW

Roof direction

Your region

3 Battery storage (optional)

Include battery?

Battery capacity

Common sizes: 5 kWh (budget), 10 kWh (typical), 13.5 kWh (Tesla Powerwall).

2 kWh10.0 kWh20 kWh

4 Export tariff

Export rate

Smart Export Guarantee rates range from 3p to 15p/kWh. The best fixed tariffs pay around 12–15p.

pence per kWh exported

5 System cost

Solar panel cost

Typical: £5,000–£8,000 for a 3–4 kW system.

£ installed

Battery cost

Typical: £2,500–£5,000 for 5–10 kWh.

£ installed

Your estimated savings

£620

Estimated annual saving

16.1

Year payback period

£5,500

25-year net return

3,320

kWh generated per year

62%

Self-consumption rate

Electricity bill savings£0

Export earnings£0

Total annual benefit£0

Total system cost£0

25-year cumulative savings vs cost

Assumptions and limitations

This calculator provides estimates based on averages. Your actual results will vary based on your specific property, shading, usage patterns, and installer quotes.

Solar generation based on MCS regional irradiance data adjusted for roof orientation and typical system efficiency (85%).
Self-consumption without battery estimated at 35–45% based on typical UK household usage patterns (Energy Saving Trust data).
Battery increases self-consumption by approximately 20–30% depending on battery size relative to generation and usage.
Annual panel degradation of 0.5% per year assumed.
No electricity price inflation applied — results shown in today’s prices. Real savings may be higher if electricity prices rise.
Battery replacement not included — modern lithium batteries typically have 10–15 year warranties.

How this calculator works

We estimate your annual solar generation using your system size, roof orientation, and regional irradiance data derived from published MCS (Microgeneration Certification Scheme) figures for the UK.

Self-consumption rates are modelled based on Energy Saving Trust research into typical UK household usage patterns. Without a battery, a typical home self-consumes 35–45% of solar generation. Adding battery storage increases this to 55–80%, depending on battery capacity relative to daily generation and usage.

Your bill saving is calculated as: (kWh self-consumed × your electricity rate). Export earnings are: (kWh exported × your export tariff rate). The payback period divides your total system cost by your annual saving.

Sources: MCS regional irradiance data, Energy Saving Trust self-consumption research, Ofgem price cap announcements, Smart Export Guarantee tariff tracker.