Flat roofs handle solar well — but the install is meaningfully different from a pitched roof and the design needs more thought. Here is what changes.
Flat-roof solar in the UK runs £1,800–£2,200 per kWp fitted in 2026 (10–20% above a pitched-roof install) due to ballasted tilt frames or penetrative mounts plus extra waterproofing. Optimal tilt is 10–15° for ballasted, 25–30° for penetrative. Parapet walls cause significant shading and need careful row spacing.