Solar on flat roofs and garages: yes, it works.

Last updated: 15 July 2026 · Written by the ECONEXIS team, MCS-accredited installers.

Flat roofs, garages, extensions and outbuildings get dismissed by a lot of installers because they're more work to design. That's their problem, not your roof's. Done properly, a flat surface is one of the easiest places to put solar — you're not stuck with the tilt and direction the builder chose, because the mounting frame sets both.

How flat-roof solar actually works

Panels laid dead flat lose output, self-shade behind dirt, and don't self-clean in the rain. So flat installs use tilt frames — rigid mounts that angle each panel up (typically 10–15°), usually weighted with ballast so nothing needs to puncture the waterproof layer. Rows are spaced so the front row's shadow never falls on the row behind, even in low winter sun. That spacing is why a flat roof takes slightly fewer panels than its area suggests — and why a design drawing matters more here than anywhere.

Garages and outbuildings: the checklist

• Structure — a single-skin garage roof may need checking before it carries panels and ballast; a decent extension or double garage usually takes it easily. We confirm this at survey.
• Roof covering — felt, EPDM rubber and GRP are all workable. If the covering is near the end of its life, re-cover first; panels last 25+ years and you don't want to lift them in five.
• Cable run — the inverter usually lives in the garage or nearby, so runs are often shorter and tidier than a loft install.
• A garage-only system can be a starter — six panels from around £4,990 installed dents a bill properly, and the system can grow later if the design allows for it (ours do).

Planning permission

Since England's planning rules were relaxed in late 2023, most domestic flat-roof installs go ahead under permitted development, within height and edge limits — conservation areas and listed buildings still need more care. We check your exact address at the free design stage, before you spend anything.

Is a flat roof worth it compared to a pitched roof?

Honestly: a well-designed flat-roof array gives up very little. Because we choose the tilt and direction, we can often point panels dead south at the ideal angle — something most pitched roofs can't offer. The trade is a few fewer panels per square metre due to row spacing. If your home has both, we'll design across both and show you the numbers side by side.

Send us a photo of your flat roof or garage and we'll tell you straight what it can do — or get a free custom design, usually back within 24 hours, anywhere across Bedfordshire, Hertfordshire, Buckinghamshire, Essex & Kent.

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