Solar Panel Savings Calculator

Calculate solar panel payback period, annual savings and 25-year return on investment.

Last updated: April 2026 · Source: Energy Saving Trust — Solar panels

£

Annual Saving

£671.50

Payback Period

8.9 years

Annual Generation

3,400 kWh

25yr Return

£10,787.50

Bill Savings (self-use)

£416.50/yr

Export Income

£255.00/yr

Disclaimer

This calculator is provided for informational purposes only and should not be considered as financial or tax advice. All calculations are performed locally in your browser — no personal data is collected or sent to our servers. Rates and thresholds are sourced from HMRC and GOV.UK and are updated for the current tax year. Always verify results with HMRC or consult a qualified professional before making financial decisions.

How It Works

Solar panels generate electricity from sunlight, reducing your reliance on grid energy. A typical UK domestic system is 3–4 kW (8–10 panels), costing £5,000–£8,000 installed. Output varies by location, roof orientation and panel efficiency, but a 4 kW system in southern England generates approximately 3,400 kWh per year.

You save money by using the generated electricity directly (avoiding the unit rate) and can earn additional income through the Smart Export Guarantee (SEG) by selling surplus electricity back to the grid. SEG rates vary by supplier but typically range from 3–15p per kWh exported.

Battery storage (£2,000–£5,000) lets you store daytime generation for evening use, increasing the proportion of self-consumption from around 30–50% to 70–80%. This calculator estimates generation, savings, SEG income and payback period based on your location and system size.

Example: 4 kW system in central England

  1. Annual generation: ~3,200 kWh
  2. Self-consumption (50%): 1,600 kWh × 24.5p = £392 saved
  3. Export (50%): 1,600 kWh × 10p (SEG) = £160 income
  4. Total annual benefit: ~£552
  5. System cost: £6,500
  6. Simple payback: ~11.8 years

Source: Energy Saving Trust — Solar panels

Frequently Asked Questions

How much do solar panels cost in the UK?
A typical 4kW domestic solar panel system costs between £5,000 and £8,000 installed. Prices vary depending on the number of panels, brand, roof type and installer. Battery storage adds £2,000-£5,000.
How much can solar panels save me?
A 4kW system typically generates around 3,400 kWh per year, saving £400-£600 on electricity bills annually depending on your usage patterns and energy tariff. With the Smart Export Guarantee, you can also earn money by selling excess electricity back to the grid.