How much electricity will solar panels generate in the UK?

In the UK, solar panels typically generate 800-1,000 kWh per kWp installed per year, depending on your location and roof orientation. A typical 4kWp system (10 standard panels) in the Midlands would generate approximately 3,500-3,800 kWh per year — enough to cover around half of an average household's electricity consumption.

What is the Smart Export Guarantee (SEG)?

The Smart Export Guarantee (SEG) is a UK government scheme that requires large energy suppliers to pay households for surplus electricity exported to the grid from solar panels and other small-scale renewable generation. Rates vary between suppliers, typically 3-15p per kWh. You need a smart meter to claim SEG payments.

How many solar panels can fit on my roof?

A standard 400W solar panel measures approximately 1.7m x 1.0m (1.7-1.8m²). A typical UK semi-detached house has around 15-20m² of usable south-facing roof, which can fit 8-11 panels (3.2-4.4kWp). You need to account for roof windows, vents, and maintaining access space around the panels.

Does roof orientation affect solar panel output?

Yes, significantly. South-facing roofs get the most sunlight and generate the most electricity (100% output). South-east or south-west facing roofs generate about 95% of optimal. East or west facing roofs generate about 85%. North-facing roofs are generally not recommended as they only generate about 55% of optimal output.

How much do solar panels cost in the UK?

As of 2025-2026, a typical 4kWp solar panel system (10 panels) costs approximately £5,000-£7,000 installed, including VAT (which is 0% for residential installations). Larger systems of 6-8kWp cost £7,000-£10,000. Battery storage adds £2,500-£5,000. Payback periods are typically 8-12 years depending on usage patterns. Solar PV can also improve your EPC rating — try our EPC rating estimator (/insulation/epc-rating-estimator/) to check.

Solar Panel Savings Estimator — UK Generation & Cost Calculator

Solar Panel Savings Estimator \u2014 UK Generation & Cost Savings

Estimate how much electricity solar panels could generate on your roof and calculate potential annual savings based on UK conditions.

Roof Details

Available Roof Area

Usable south-facing (or nearest) roof area

Roof Orientation

Direction the roof faces

Panel Type

UK Region

Electricity & Usage

Electricity Price

Current Ofgem cap: ~24.5p/kWh (check your tariff)

Self-Use Percentage

30-50% without battery, 70-80% with battery

How We Calculate This

This estimator calculates how many solar panels can fit on your available roof area, the total system size in kWp, and the expected annual electricity generation based on your UK location and roof orientation.

The calculations

Number of panels = Available roof area ÷ Panel area (m²)

System size (kWp) = Number of panels × Panel wattage ÷ 1000

Annual generation = System kWp × Regional kWh/kWp × Orientation factor

UK generation figures

South England: 950-1,000 kWh per kWp per year
Midlands: 875-950 kWh per kWp per year
North England: 850-900 kWh per kWp per year
Scotland: 800-875 kWh per kWp per year

Savings calculation

Your savings come from two sources: electricity you use directly from the panels (saving you the full retail electricity price), and excess electricity exported to the grid under the Smart Export Guarantee (SEG). The self-use percentage depends on your daytime electricity consumption and whether you have battery storage \u2014 typically 30-50% without a battery and 70-80% with one.

Smart Export Guarantee (SEG)

We use an estimated SEG rate of 4.1p/kWh for exported electricity. Actual rates vary by supplier and can range from 3p to 15p/kWh. Check the latest SEG rates from your energy supplier to refine your estimate.

Frequently Asked Questions

Last updated: February 2026

All calculations are estimates. Verify with your supplier.

Solar Panel Savings Estimator \u2014 UK Generation & Cost Savings

Roof Details

Electricity & Usage

How We Calculate This

The calculations

UK generation figures

Savings calculation

Smart Export Guarantee (SEG)

Frequently Asked Questions

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