Rooftop vs ground-mounted commercial solar — which wins?
Two very different projects that end up on the same balance sheet. Here's the side-by-side on cost, planning, yield, self-consumption and lifetime economics for UK businesses in 2026.
Key takeaways
- Rooftop commercial solar avoids extra land use and generally costs 10% to 15% less per kWp than ground-mounted alternatives.
- Ground-mounted systems allow optimal tilt and orientation for higher generation, but usually require full local planning permission and fencing.
- Rooftop solar under 1MW benefits from Permitted Development Rights, delivering faster commissioning and quicker financial payback for UK businesses.
Side-by-side comparison
Installed cost
Rooftop: £900–£1,200/kWp at 100–500 kWp. Ground-mount: £700–£850/kWp at 500 kWp+. Ground-mount wins on £/kWp at scale, rooftop wins on total project cost under 250 kWp.
Yield
Ground-mount south-facing at optimum tilt beats an equivalent east-west rooftop by 10–20%. Rooftop wins vs shaded or steep-pitch ground sites.
Planning risk
Rooftop up to 1 MW is permitted development on most commercial buildings. Ground-mount over 50 kW needs full planning permission — 6–9 months and 5–10% risk of refusal.
Self-consumption
Rooftop is next to the load — 70–90% self-consumed is normal. Ground-mount via private wire can match, but often needs a metered supply agreement.
Business rates
Both are exempt from business rates until 2035 in England (2023 rules). No difference.
Rule of thumb
Under 500 kWp with a sound roof: rooftop, every time. Above 1 MW, on a large site with spare land: ground-mount usually wins. In between, the deciding factors are roof age, planning appetite and how much of the output you'll self-consume.
Related reading
FAQ
Rooftop or ground-mount — which is better?
Rooftop wins for most SMEs with a suitable roof: no land use, no planning permission below 1 MW, and the array sits directly over demand for maximum self-consumption. Ground-mount wins at 500 kWp+, on weak or short-life roofs, or when you have available land.
Is ground-mount cheaper per kWp?
Yes at 500 kWp+ — typically £700–£850/kWp vs £900–£1,100/kWp for rooftop. But land, security fencing, grid connection and planning add ~15% back once fully costed.
Do rooftop panels damage the roof?
No — properly designed clamped or ballasted arrays don't penetrate the membrane and often extend roof life by protecting the surface from UV. A structural survey confirms load capacity before install.
Can I combine both?
Yes, and larger sites often do — a factory rooftop for on-site consumption plus a ground-mount for export or private wire to a neighbour. One G99 application can cover both if the DNO connection allows.
Which has better ROI?
Depends entirely on the site. Rooftop typically hits 12–18% IRR; ground-mount 10–14% (planning drag). Ground-mount wins in absolute £ saved at 1 MW+.
Get a comparison on your specific site
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