How-To · Updated June 2026
How to Plan a Solar Panel Roof: 2026 Walk-Through (UK)
Planning a solar PV roof well is what decides whether it pays back in 8 years or 15. The job breaks into five stages: assess the roof (pitch, orientation, condition), check shading, size the system to your actual electricity use, plan the inverter and any battery, then book an MCS-certified installer so you qualify for the Smart Export Guarantee. This walk-through takes you through each step before you ever request a quote, so you know what to ask for.
Roof & shading System sizing MCS & export
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✅Reviewed by the BestBuilders editorial team on 16 June 2026. All technical steps, MCS and Smart Export Guarantee references verified against current 2026 scheme rules. Editorial standards: /editorial-standards.
Step by Step
5 Steps to Plan Your Solar Roof
- Assess the roof. A south-facing roof at a 30–40° pitch is ideal, but east–west splits work well too. Check the roof covering has 15+ years of life left — it's far cheaper to re-roof before panels go on than after.
- Map the shading. Note chimneys, trees, aerials and neighbouring roofs that cast shade between roughly 9am and 4pm. Even partial shade on one panel can drag down a whole string unless you use optimisers or microinverters.
- Size the system to your usage. Pull a year of electricity bills. A typical UK home uses 2,700–4,000 kWh a year; a 3.5–5 kWp array (about 9–13 panels) suits most homes. Bigger isn't always better if you can't use or store the daytime generation.
- Plan the inverter and battery. Decide where the inverter goes (loft, garage or utility — cool and ventilated) and whether a battery makes sense for your usage pattern. A battery raises self-consumption but lengthens payback.
- Book an MCS-certified installer. Only an MCS install qualifies you for the Smart Export Guarantee, which pays you for surplus power. Get at least three MCS quotes and compare panel brand, inverter, warranty and the export tariff on offer.
Watch For
Common Planning Mistakes
- Oversizing the array. Panels you can't self-consume only earn the lower export rate — size to your usage, not your roof.
- Ignoring roof condition. Fitting panels onto a roof that needs replacing in five years means paying to remove and refit them.
- Skipping shading analysis. One shaded panel without optimisers can cut a string's output sharply.
- Using a non-MCS installer. You lose access to the Smart Export Guarantee and most manufacturer warranties.
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Frequently Asked
Common Questions
South-facing at a 30–40° pitch gives the highest annual yield, but east–west roofs are increasingly popular because they spread generation across morning and evening, which can match home usage better. North-facing alone is rarely worth it.
Most UK homes suit a 3.5–5 kWp array (roughly 9–13 panels), sized against annual electricity use of 2,700–4,000 kWh. The right size is the one whose daytime output you can actually use or store, not the largest your roof can hold.
For most homes, roof-mounted panels are permitted development as long as they don't project far above the roof plane. Listed buildings and conservation areas often need permission, so check with your local authority before committing.
An MCS-certified installation is required to qualify for the Smart Export Guarantee, which pays you for electricity you export to the grid, and is usually a condition of manufacturer warranties. Always confirm certification before booking.
A battery raises how much of your own generation you use rather than export, which suits homes that use most power in the evening. It adds cost and lengthens payback, so model it against your usage pattern rather than fitting one by default.
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