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.
Planning the work? Check what it usually costs, or work out your own estimate. The free quote form is at the top of this page.
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.
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.
Common Questions
Related Guides
More solar and renewable-energy guides. Before you book anything, three practical checks save time later: confirm your consumer unit and roof structure can take the extra load, note where cabling will run from roof to inverter, and register the export connection with your Distribution Network Operator — systems up to 3.68kW per phase can be notified after commissioning, while larger arrays must be approved first. It also helps to know that domestic solar and battery installations carry 0% VAT until 31 March 2027, and that roof-mounted panels are permitted development on most homes provided they sit close to the roof plane. For the wider picture, see our guides on how to choose a solar installer, whether solar panels need planning permission and whether a solar battery is worth it.