Ground-mount vs roof-mount commercial solar — which suits your site?

The default for commercial solar is the roof — it's dead space you already own, and it's usually the cheapest, simplest option. But it's not the only one, and it isn't always the best. If you have spare land, or a roof that can't take panels, ground-mount is worth understanding. Here's how the two stack up.

Roof-mount: the sensible default

In its favour:

• No land cost. You're using space that's otherwise doing nothing.
• Usually no planning application. Since the 1MW cap was removed in 2023, most commercial rooftop solar is permitted development (see planning permission).
• Shorter cabling runs from panels to your switchgear, and the array sits right where the power is used.
• Generally lower cost per kWp for a straightforward install — no groundworks, foundations, or fencing.

The constraints:

• The roof limits the system size. You can only fit what the roof holds, which may be less than your consumption justifies.
• Roof condition and structure matter. An old roof, a weak structure, or awkward orientation/shading can rule it out or add cost (see the site survey).
• Maintenance access is harder. Cleaning and repairs mean working at height.
• It's tied to the roof's life. If you re-roof in ten years, the panels have to come off and go back on.

Ground-mount: when land changes the picture

In its favour:

• Scale. The system is limited by land, not roof area, so you can build bigger — useful if your demand outstrips what the roof can supply.
• Optimal orientation and tilt. Ground arrays can be set due south at the ideal angle, maximising yield, rather than being dictated by the roof's shape.
• Easy access. Maintenance, cleaning, and repairs are at ground level — cheaper and simpler over the system's life.
• Roof-independent. No structural worries, and re-roofing never disturbs the array.

The costs and catches:

• It uses land that might have other value (parking, expansion, yard space).
• Groundworks and foundations, perimeter security/fencing, and longer cabling/trenching back to your building all add cost.
• It usually needs planning permission. Unlike rooftop, ground-mount beyond a small size is not permitted development and requires a full planning application — adding time and uncertainty.

The hybrid worth knowing: solar carports

If your "spare land" is a car park, solar carports (canopies) are a third option: panels on raised structures over parking. You get ground-mount's access and orientation benefits, keep the land's primary use, provide shade and shelter, and create a natural home for EV charging fed by your own solar. They cost more per kWp than a simple ground array (the structure isn't free), but for a site with a large car park and an EV-charging ambition, they can be the smart play.

How to decide

Work through it in order:

1. Is your roof suitable — sound structure, reasonable orientation, not heavily shaded, with years of life left? If yes, start there; it's usually cheapest and avoids planning.
2. Is the roof big enough for the system your consumption justifies? If the roof caps you well below your demand, ground-mount (or a roof-plus-ground mix) lets you build to the right size.
3. Do you have land you can spare, and the appetite for a planning application? If yes, ground-mount unlocks scale and ideal orientation.
4. Got a big car park and EV plans? Price a solar carport against both.

Sanity-check

1. Roof condition and remaining life — confirmed by survey?
2. Roof capacity vs your demand — does the roof alone meet your needs?
3. Spare land — genuinely available, or earmarked for something else?
4. Planning — have you factored the application time/cost for a ground array?

The bottom line

For most SMEs the roof is the right answer: cheapest, fastest, usually no planning. Reach for ground-mount when the roof is unsuitable or too small for the system you need — accepting that you're trading the roof's simplicity for land use, groundworks, and a planning application. And if you've a large car park, let a solar carport into the comparison, especially with EV charging on the horizon.

To size a system against your usage, run the calculator. For orientation strategy, see south-facing vs east-west arrays; for the planning detail, planning permission for commercial solar. Monthly intel: the Brief.

General information. Confirm roof suitability by survey and planning status with your local authority.