UK calculator

Solar Panel Savings Calculator UK

Estimate annual bill savings from solar panels by comparing self-consumed generation, exported electricity and your current electricity use.

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Quick estimate

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Enter a few key details to get an instant returns estimate.

Representative estimate

Compare solar, storage and combined investment paths.

Baseline spend without upgrades is £37,662 over 20 years.

Decision summary

Ready when you are

Add the property basics to build your initial quote. This first pass can reach up to 50% confidence before a more tailored quote is unlocked.

0% initial quote completion

Solar + battery looks strongest

Your initial quote points to solar + battery as the best investment option based on your details when modelled with our assumptions.

Projected net profit£20,958

Estimated ROI162%

Based on a 20-year horizon.

Estimate confidence0%

To increase your estimate accuracy, create a personalised quote with tailored usage, roof, installation and household details.

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Solar only

Representative estimate

Projected net profit£17,379

Payback: 8.7 yrs
Annual benefit: £825
Upfront cost: £7,200
Generation: 3,880.1 kWh

1,872.2 kWh self-consumed, 2,008 kWh exported.

Sensitivity range: £13,556 to £20,507.

How this scenario is calculated

Annual consumption uses electricity-consumption-v1-manual-seed-2026-05 at 3,800 kWh/year (good directional confidence).
Generation lookup uses UK Average at 907 kWh per kWp per year for a south-west roof.
Average semi-detached install size assumed at 4.6 kWp across 23 m2 of roof area.
Solar cost model uses £2,100 fixed plus £1,100 per kWp for semi-detached homes.
Energy prices assumed to rise by 4% per year.
Standing charge held constant at £201 per year.
Self-consumption estimated at 48% based on occupancy, day usage and storage.

Battery only

Representative estimate

Projected net profit£275

Payback: 28.4 yrs
Annual benefit: £201
Upfront cost: £5,700
Generation: 0 kWh

0 kWh self-consumed, 0 kWh exported.

Sensitivity range: £214 to £324.

How this scenario is calculated

Annual consumption uses electricity-consumption-v1-manual-seed-2026-05 at 3,800 kWh/year (good directional confidence).
Generation lookup uses UK Average at 907 kWh per kWp per year for a south-west roof.
Average semi-detached install size assumed at 4.6 kWp across 23 m2 of roof area.
Solar cost model uses £2,100 fixed plus £1,100 per kWp for semi-detached homes.
Energy prices assumed to rise by 4% per year.
Standing charge held constant at £201 per year.
Battery-only value estimated from off-peak charging arbitrage against the import tariff.

Solar + battery

Best fit today

Representative estimate

Projected net profit£20,958

Payback: 11.3 yrs
Annual benefit: £1,137
Upfront cost: £12,900
Generation: 3,880.1 kWh

2,725.8 kWh self-consumed, 1,154.3 kWh exported.

Sensitivity range: £16,347 to £24,731.

How this scenario is calculated

Annual consumption uses electricity-consumption-v1-manual-seed-2026-05 at 3,800 kWh/year (good directional confidence).
Generation lookup uses UK Average at 907 kWh per kWp per year for a south-west roof.
Average semi-detached install size assumed at 4.6 kWp across 23 m2 of roof area.
Solar cost model uses £2,100 fixed plus £1,100 per kWp for semi-detached homes.
Energy prices assumed to rise by 4% per year.
Standing charge held constant at £201 per year.
Self-consumption estimated at 70% based on occupancy, day usage and storage.

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How this is calculated

Assumptions used for this estimate

Electricity model: Representative estimate
Estimated annual use: 3,800 kWh
Model range: 2,774-5,016 kWh
Monthly shape: standard-electric
Solar system: 4.6 kW
Solar cost: £7,200
Battery: 8.3 kWh
Battery cost: £5,700
Import tariff: 28p/kWh
Export tariff: 15p/kWh
Daytime use: 45%
Energy inflation: 4%

Savings come from two places

Solar panel savings come from avoided imports and export income. Avoided imports are usually more valuable because every kWh used at home avoids the full retail import rate, while exported electricity is paid at the export tariff.

Daytime usage increases the value of solar generation.
Export tariffs improve the value of surplus generation.
A battery can move daytime generation into evening demand.
Standing charges usually remain even when solar reduces unit charges.

Why a useful estimate needs a range

Weather, shading, occupancy, appliance use and tariff changes all affect savings. Solar ROI records assumptions and presents sensitivity instead of implying that one annual saving is guaranteed.

FAQs

Common questions

Are solar panels worth it in the UK?

They can be, but the result depends on electricity use, roof direction, installation cost, export tariff and whether you add battery storage. Solar ROI is designed to show payback and a range, not just one headline saving.

How does electricity usage change payback?

Higher daytime electricity use usually improves solar payback because more generated energy offsets imported electricity. Low daytime use can still work, especially with a battery or a strong export tariff.

How does the Smart Export Guarantee affect savings?

The Smart Export Guarantee pays for exported solar electricity. Higher export rates can improve savings, especially for homes that export a larger share of generation.

Which export tariff does Solar ROI assume?

The default model uses a 15p/kWh export assumption because several leading export tariffs cluster around that level, but the calculator shows assumptions clearly and the methodology explains how changing export income affects payback.

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