Checks Out
All calculators
Home Grants & Energy2 min check

Solar Panel Savings Calculator

Estimate how much a residential solar PV system could save you each year, plus typical payback period.

Short answer

A typical 4kWp south-facing UK solar PV system generates ~3,400–3,800 kWh/year, costs £5,500–£8,000 installed, and saves £900–£1,400/year via self-consumption + export (SEG payments at 5–15p/kWh). Payback: 6–9 years; system lifetime: 25+ years. Adding a 5kWh battery doubles self-consumption and adds £200–£400/year.
Step 1 of 20%

Your system

kWp

Typical UK home: 3–5 kWp.

Adding a battery?

Calculation method, coverage and version

Inputs used
System size (kWp), Roof orientation, Adding a battery?, Electricity rate (p/kWh), Roughly what % of generation could you use directly?, Quoted install cost (£).
Calculation approach
The calculator applies the rules and assumptions described in “How it works” to the values you enter. Rounding can cause small differences from an official or provider calculation.
Coverage
Home Grants & Energy. UK nations, tax treatment, local rules and provider criteria can differ; check the official sources shown below before acting.
Content version
No page-specific review date is currently published. Treat the result as indicative and verify current rules independently.
Not included unless explicitly requested: personal circumstances not entered, provider discretion, future rule changes, professional fees and case-specific exceptions. Read the full calculator methodology.

Primary sources and official verification

Use these official sources to verify current rules before acting. Coverage and dates can differ across England, Scotland, Wales and Northern Ireland.

See the sitewide source policy.

How it works

The calculator combines roof size, orientation, shading and your annual electricity use to estimate generation, self-consumption (the bit you use directly), and export (sold via the Smart Export Guarantee). Generation is calculated using regional irradiance data; tariff savings use 2025 price cap rates.

Worked example

4kWp south-facing London roof, no shading, household using 4,000 kWh/year: generates ~3,700 kWh, uses ~1,500 kWh directly (saves £400), exports 2,200 kWh (earns £330 at Octopus 15p SEG) — total £730/year. With a 5kWh battery: ~£1,100/year, payback ~7 years.

Who should use this

  • •Homeowners with south, east or west facing roofs
  • •High daytime electricity users (EVs, heat pumps, working from home)
  • •People planning to stay 5+ years

Common mistakes

  • ×Going for the cheapest panels — quality inverter matters more
  • ×Skipping the battery if you're often out during the day
  • ×Forgetting MCS certification — required for SEG payments and warranties
  • ×Believing 'free solar' deals — you sign over the export income for 25 years

Frequently asked questions

Is there a government grant?▾

No direct grant for owner-occupiers since FiTs ended in 2019. ECO4 occasionally funds solar for low-income homes; 0% VAT on installs runs until 2027.

What's a good SEG tariff?▾

Octopus Outgoing Fixed (15p) and Intelligent Octopus Flux (up to 35p peak) lead the market. Most others pay 5–7p.

Do they work in winter?▾

Yes, but at ~25% of summer output. Annual figures already account for this.

Related calculators

Heat Pump Cost Calculator →EPC Improvement Planner →Energy Bill Savings Calculator →EV Charging Cost Calculator →