Solar Panels Cost, EPC Rating Impact and the Smart Export Guarantee in 2026

How Solar Panels Affect Your EPC Rating

Solar photovoltaic (PV) panels generate electricity from daylight, reducing the amount of grid electricity your home consumes. Under the SAP methodology used to calculate EPC scores, on-site renewable electricity generation is credited directly against the property's calculated energy demand. This can deliver a substantial SAP score improvement — typically 10–15 points for a standard 3.5 kWp system on a 3-bedroom semi-detached house.

For context: a property currently sitting at SAP 58 (lower D band) could move to SAP 70 (C band) from solar panels alone, without any changes to insulation or heating. For landlords under pressure to meet future MEES requirements and for owner-occupiers wanting to access green mortgage products, this is a compelling proposition.

Installed Cost of Solar Panels in 2026

System costs have fallen significantly over the past decade and continue to decline. In 2026, a typical residential installation costs:

Costs vary by region, roof orientation, installer, and whether scaffolding is required. South-facing roofs at a 30–40° pitch produce the most energy, but south-east and south-west orientations are nearly as effective. East or west-facing roofs produce roughly 20% less.

Battery Storage

Adding a battery storage system (4–10 kWh capacity) allows you to store surplus solar generation during the day and use it in the evenings, increasing self-consumption from around 30–40% without storage to 60–80% with storage. Battery storage typically adds £3,000–£6,000 to installation cost. Under SAP, batteries are not currently modelled in a way that generates additional EPC points, but they do reduce bills meaningfully.

The Smart Export Guarantee (SEG)

Under the Smart Export Guarantee, all licensed electricity suppliers with more than 150,000 customers are legally required to offer a tariff to small-scale generators — including domestic solar panels — for surplus electricity exported to the grid. SEG rates in 2026 vary by supplier from around 3–15p per kWh depending on the tariff (some suppliers offer time-of-export rates that pay more during peak demand periods).

For a 3.5 kWp system exporting roughly 1,000–1,500 kWh/year, SEG income is £30–£225/year depending on the rate secured. This contributes to payback but is secondary to bill savings from self-consumed generation.

Payback Period

With a 3.5 kWp system costing £6,000 and a household consuming roughly 50% of generated electricity (the rest exported under SEG):

• Annual bill saving from self-consumption: approximately £450–£600 at current tariffs
• Annual SEG income: approximately £50–£150
• Total annual benefit: approximately £500–£750
• Simple payback: **8–12 years**

Solar panels typically carry a 25-year performance warranty, so the economics are sound. Payback improves if electricity prices rise, or if you increase self-consumption through a battery or EV charging.

Do Solar Panels Require Planning Permission?

In most cases, no. Solar panels on domestic roofs are a permitted development in England, provided the installation does not protrude more than 200mm from the roof surface and the property is not in a conservation area or a listed building. Check with your local planning authority if your property has any designations.

EPC Assessment and Solar Panels

An EPC assessor will record your solar panel system's capacity and orientation. The SAP calculation credits the expected generation against your home's modelled energy use. If you install solar panels after your current EPC was issued, it is worth commissioning a new EPC to capture the improvement — particularly if you are a landlord preparing for future MEES requirements.

Use the [EPC Improvement Calculator](/epc-improvement-calculator) to model how solar panels would affect your specific property's EPC rating alongside other potential improvements.