Solar Carports vs Rooftop Solar: Which Is Right for Your Site?

If you own a building with a car park, you have two places to put solar: on the roof or over the parking. They are not rivals so much as tools for different jobs, and choosing well starts with an honest look at the numbers. Rooftop solar is the cheaper, faster-payback option and should usually be your first move. A solar carport costs more and takes longer to pay back — but it unlocks generation, shelter and EV charging that a roof simply cannot provide. This guide lays out the real figures for the UK in 2026, then works through when the roof wins, when a canopy wins, and why a great many sites end up doing both.

The headline numbers, side by side

The clearest way to compare is cost per kWp of installed capacity, because it strips out how big the system is.

• Rooftop solar: £700-£1,050/kWp. You are mounting panels onto a structure that already exists, so you pay for the modules, inverter, cabling and electrical works — and little else.
• Solar carports: £900-£1,400/kWp at commercial scale. Smaller or more complex structures — tight sites, awkward groundworks, low bay counts — run higher, at £1,200-£3,000/kWp. In per-bay terms, budget roughly £6,000-£12,000 per parking bay.

The gap between the two is not a mark-up; it is a whole extra structure. On a carport, the steel frame and foundations make up around 45% of the total cost. You are buying a roof — engineered to stand up to wind and snow with cars and people underneath it — that a rooftop system gets for free. That single fact explains almost every difference that follows.

For a fuller breakdown of what drives canopy pricing, see our cost guide.

Payback: where the roof pulls ahead

Cheaper hardware plus no structure means the roof pays back sooner.

• Rooftop payback: 4-6 years.
• Solar carport, solar-only: 8-12 years.
• Solar carport with EV charging: 7-11 years.

We will not quote you a five-year solar-only payback on a carport, because it is not realistic — anyone who does is either ignoring the structural cost or hoping you will not check. That said, longer payback is not the same as worse value. A well-built canopy is a 25-year-plus asset engineered to Eurocode 1 (BS EN 1991) wind and snow standards, so the years after break-even are close to free electricity — and the canopy delivers shade, weather protection and EV-ready infrastructure that a bare roof never will. The right question is not “which pays back faster?” but “which job am I trying to do?”

When the roof wins

For most buildings, the roof should be the first place you look. It wins clearly in these situations.

You have suitable, unused roof space. A large, south-facing or east-west roof with a sound structure and few obstructions is the cheapest generation you can buy. At £700-£1,050/kWp and a 4-6 year payback, nothing beats it on pure return. Fill the roof first.

Budget or payback is the deciding factor. If the business case lives or dies on the shortest possible payback — or capital is tight and every year of return counts — the roof is the rational choice. You are not paying for 45% of the system to be structural steel.

You want the simplest planning and connection path. Rooftop solar on an existing commercial building is typically the least complicated route. A carport, by contrast, is a new structure with its own siting, design and drainage considerations.

The parking is the wrong shape or shared. Not every car park suits a canopy. Sites with heavy vehicle movements, unusual layouts, or parking you do not control long-term may be better served by putting the panels overhead on the building instead.

In short: if the roof can carry the array you need and payback is your priority, the roof wins. Do not build a canopy to solve a problem your roof does not have.

When a canopy wins

A solar carport earns its higher cost when the roof cannot do the job — or when you need what only a canopy provides.

The roof is full, unsuitable, listed or unavailable. This is the most common trigger. If you have already maximised the roof, or it is too weak, too shaded, too cluttered with plant, or the building is listed (where rooftop changes are heavily restricted), the car park becomes your best remaining surface. A canopy lets you keep generating when the roof has nothing left to give.

You need EV charging. This is where a canopy genuinely outperforms a roof, because it puts the panels directly above the cars. Self-consumed solar is worth roughly twice what you earn exporting it: solar generated under your canopy costs around 10p/kWh, against grid electricity at 30-47p/kWh. Cars parked through the middle of the day soak up midday generation almost perfectly. A canopy comfortably powers 7kW and 22kW AC charging plus site lighting — though, to be straight with you, it will not run standalone 50kW+ DC rapid chargers on its own; those need a grid connection and battery storage. For workplace and destination charging, a canopy is an ideal fit, which is why it drops payback to 7-11 years. See our page on EV-charging solar canopies for the full pairing.

You value the shelter and the customer experience. A canopy keeps cars, staff and customers dry and shaded. For retail, hospitality, workplaces and public-sector sites, that covered parking is a tangible benefit a rooftop array cannot offer — it is generation and amenity in one structure.

You want to future-proof against a car-park solar requirement. The much-discussed car-park solar mandate is, as of mid-2025, only a call for evidence (May-June 2025) — not law. We will not pretend otherwise. But building now lets you future-proof before any such requirement lands, on your own timetable rather than a regulator’s.

The economics can genuinely stack up

The higher cost of a canopy does not mean weak returns — the generation is real. DESNZ modelling from May 2025 found an 80-space car park could save around £28,000 a year on electricity through self-consumption. And there is a live, funded public-sector example: the Princess Royal Hospital in Telford is building a 200 kW solar car-park canopy, backed by £445,000 of Great British Energy funding, projected to save around £35,000 a year, with works from early 2026. That is a concrete demonstration that a canopy over a busy car park pays its way.

On sizing, a standard bay carries about 2 kWp (four to six 450W panels), so a 100-bay car park supports roughly 180-270 kWp; a double-sided, back-to-back layout can lift that toward 4 kWp per bay. UK yield runs about 900-950 kWh per kWp, and bifacial panels — capturing light reflected off the pale car-park surface — add a further 5-12%.

Why many sites do both

The roof-versus-canopy framing is often a false choice. On a lot of commercial sites the best answer is both, in sequence: fill the roof first for its fast payback, then extend onto the car park when you have exhausted the cheaper surface or when EV demand justifies the canopy.

Doing both makes sense because the two assets complement each other. The roof gives you the lowest-cost generation and the quickest return; the canopy adds capacity you could not otherwise reach, plus the EV charging and shelter the roof cannot provide. A phased approach also spreads capital: roof this year, canopy when the charging demand or the budget arrives. The generation from both feeds the same site load, and the more you self-consume — at 10p against 30-47p grid — the better the whole system performs.

If you are weighing this up, we will model your roof and your car park together and tell you honestly where each pound is best spent.

Planning, grid and funding — the practical differences

A few operational points shape the decision beyond headline cost.

Planning. In England, a solar canopy over non-domestic, off-street parking falls under the Class OA permitted development right (in force since 21 December 2023). That means a prior-approval application on siting, design and glare — not a full planning application — subject to limits: no part over 4m high, more than 10m from any dwelling, excluding listed buildings and scheduled monuments, a SuDS drainage condition over permeable surfaces, and construction started within three years. Crucially, this is England only — Wales, Scotland and Northern Ireland still need standard planning permission. Domestic carports follow householder permitted development as an outbuilding (max 4m high, 3m within 2m of a boundary, behind the principal elevation, under 50% of the curtilage), with applications required for listed buildings, conservation areas and National Parks. A rooftop retrofit on an existing building is usually the simpler planning route.

Grid connection. Small systems up to 3.68kW per phase use the simple G98 fit-and-inform route. Most commercial canopies — and larger rooftop arrays — exceed that and need G99 pre-approval from the DNO, typically 4-8 weeks (up to 8-12). To claim the Smart Export Guarantee, the system must be MCS-certified.

Funding. Much of the support applies to both roof and canopy. Businesses use the £1m Annual Investment Allowance and the 50% First-Year Allowance — but note solar is a special-rate asset and is excluded from full expensing, so treat any “full expensing” claim as a red flag. England offers a business-rates exemption on renewable generation to 31 March 2035. The Smart Export Guarantee pays roughly 1-15p/kWh for export. The Workplace Charging Scheme (open to 31 March 2027, up to £500/socket, £2,000 for state education, 75% of cost, up to 40 sockets, via an OZEV-authorised installer) offsets the chargers under a canopy. Great British Energy capital is available for the NHS and schools, and Salix offers 0% loans to schools. Domestic solar carries 0% VAT to 31 March 2027, though whether that extends to a standalone canopy is not confirmed by HMRC — check your case. Two schemes are closed and should not feature in your plan: the Public Sector Decarbonisation Scheme (closed to new applicants November 2024) and the staff-and-fleets EV infrastructure grant (closed 31 March 2026). The full, current picture is on our grants and funding page.

The bottom line

Use the roof first: at £700-£1,050/kWp and 4-6 year payback, it is the cheapest, fastest solar you can buy, and it wins wherever you have suitable, unused roof space and payback is your priority. Reach for a solar carport when the roof is full, unsuitable, listed or unavailable, when you need EV charging, or when covered parking adds real value — accepting £900-£1,400/kWp and an 8-12 year payback (7-11 with charging) for capacity and benefits the roof cannot deliver. And on many sites, the honest answer is to do both, in the right order.

We are a turnkey, MCS-certified installer — structure, PV, electrical and DNO connection under one contract, not a bare frame — accredited with MCS, NICEIC, RECC and TrustMark, and backed by an IWA workmanship warranty. If you would like your roof and your car park assessed together, request a free quote or call +44 7707 970661. For the car-park side specifically, see our page on solar carports for car parks.