The State of UK Commercial Rooftop Solar 2026

How big is the opportunity?

Across England & Wales, Sunseam ranks 137,849 commercial buildings of 1,000 m² or more. Fitted with rooftop solar they could host an estimated 40,561 MWp of generation and cut bills by about £6.1bn a year, while displacing roughly 8.0m t of CO₂ annually.

Why now, economics first, EPC second

The primary driver is economics: rising commercial electricity and grid charges against a typical rooftop-solar payback of about 4–9 years mean the value is there to capture today. On top of that, around 30% of these buildings sit at EPC Band D–G (40,900roofs). The minimum to let is Band E now; the government's long-term MEES target is EPC B for large non-domestic buildings (over 1,000 m²), expected ~2031, so the biggest, lowest-rated roofs also have a future-proofing reason to act, and solar both cuts bills and lifts a building's rating. (The previously proposed 2027 “Band C” commercial step was dropped in 2026.)

FAQ

Methodology

Sunseam analysis of official UK public data. Figures are estimates, not measured values or guarantees. We include non-domestic buildings of 1,000 m² or more, de-duplicated to the latest record per building, and exclude roofs that already have solar. System size is type-aware (single-storey sheds ≈ full roof, multi-storey ≈ less) at ~7 m²/kWp; generation ~950 kWh/kWp/yr; benefit uses a £0.28/kWh import price and £0.08/kWh export, with self-consumption modelled per building (it varies with daytime load), the avoided-bill saving is capped at each building's own bill and export income is counted separately on top; CO₂ uses ~0.207 kgCO₂/kWh. England & Wales only.