Commercial solar carport myths, corrected
Solar carports sit where construction, planning law and grid engineering meet, so they attract more folklore than almost any other renewable project. Here is the corrected 2026 position. In England a commercial canopy is usually a prior-approval matter under Class OA, not full planning. Scotland grants it outright under Class 9M. Commercial VAT is 20% and normally recoverable, not zero. Solar is special-rate plant claiming the Annual Investment Allowance plus a 50% first-year allowance, not full expensing. And a carport costs roughly two to three times a rooftop system per kWp, because you are buying steel as well as panels. The table separates each myth from the fact, including the points the industry gets right.
We install carports for a living, so each claim below is set against what the rules and the numbers actually say. Where a myth is really a half-truth we say so, and where a genuine downside exists we agree with it rather than paper over it.
Myth versus fact
| Myth | Fact |
|---|---|
| You always need full planning permission for a commercial solar carport. | In England, since 21 December 2023, Class OA gives a prior-approval right, not full planning: canopies up to 4m, more than 10m from a dwelling, excluding listed or scheduled sites, no adverts, determined within 56 days and completed within 3 years. |
| SuDS drainage is assessed as part of prior approval. | No. Prior approval covers siting, design and glint or glare only. Sustainable drainage for run-off is a mandatory condition of the right, not a prior-approval matter you argue at the decision. |
| Scotland needs full planning for the canopy. | No. Class 9M (in force 24 May 2024) makes a non-domestic solar canopy permitted development outright. An attached battery goes through a prior-approval notification. Wales and Northern Ireland generally do need full planning, case by case. |
| Commercial installs get 0% VAT like homes do. | No. The 0% rate is residential only, to 31 March 2027, then 5%. Commercial work is standard-rated at 20%, usually recoverable if you are VAT-registered. A standalone carport is not expressly covered by HMRC, so confirm per project. |
| Solar qualifies for 100% full expensing. | No. Solar PV is special-rate plant, so it does not get full expensing or the 40% main-rate first-year allowance. It uses the £1m Annual Investment Allowance at 100%, or the permanent 50% first-year allowance for companies. Take your own tax advice. |
| A carport pays back in about three years. | Not for solar alone. At UK yields of roughly 900 to 950 kWh/kWp, realistic solar-only payback is about 8 to 10 years. EV-charging revenue or high self-consumption shortens it, but a three-year figure ignores the cost of the structure. |
| A carport costs about the same as a rooftop system. | No. The steel structure is roughly 40 to 50% of the bill, so a carport runs about £1,100 to £1,600/kWp at scale against £700 to £1,050/kWp on a roof, near two to three times the rooftop rate per kWp. |
| You can have a commercial system installed in a few days. | Rarely. Most commercial arrays exceed 3.68kW per phase, so they need a G99 application to the DNO, commonly 8 to 16 weeks before energisation. Only sub-3.68kW single-phase jobs use the simpler G98 route. |
| Any general electrician can install it. | A carport is a structural build plus a grid-tied PV array. It needs foundation and structural design, MCS-standard workmanship and G99-competent electrical work, not a general electrician working outside their scope. |
| Concede: solar carports are more expensive per kWp than rooftop. | True, and we say so plainly. You are buying a structure and covered parking as well as generation, so the premium is real. Build a carport where the parking, canopy shelter and EV-charging value justify the steel, not as a cheaper route to kWp. |
Planning: prior approval, not a blanket refusal
The biggest myth is that every commercial canopy needs full planning. In England it usually does not. Class OA, in force since 21 December 2023, created a permitted-development right for solar canopies over off-street parking. The prior-approval process asks the council to consider siting, design and glint or glare within 56 days. It is not the open-ended discretion of a full application. The limits are specific: the canopy must be no more than 4m tall, sit more than 10m from a dwelling, avoid listed and scheduled sites and carry no advertising, and the works must be completed, not merely started, within 3 years. Because Class OA is a standing right, there is no deadline to rush toward. We cover the detail, including the exclusions that push a scheme back into full planning, on our solar carport planning permission page.
Scotland is more generous still. Under Class 9M (in force 24 May 2024) a non-domestic solar canopy is permitted development outright, with any attached battery handled through a prior-approval notification. So the claim that Scotland needs full planning for the canopy is simply wrong. Wales and Northern Ireland are the exceptions where full planning is generally required, judged case by case, which is why the mode of consent should be confirmed before design work begins.
Drainage is a condition, not a prior-approval test
A subtler myth is that you can be refused prior approval on drainage grounds. Under Class OA the matters the council weighs are limited to siting, design and glint or glare. Sustainable drainage for surface-water run-off from the new canopy area is a mandatory condition attached to the right, not one of the prior-approval matters. In practice that means you still have to design and deliver appropriate SuDS, but you are not arguing it at the prior-approval decision. Getting this distinction right keeps a scheme on the permitted-development track instead of tipping it into a full application.
VAT and tax: where the numbers get inflated
Two of the most persistent myths inflate the financial case. The first is that commercial installs get 0% VAT. They do not. The 0% rate is residential only and runs to 31 March 2027 before reverting to 5%. Commercial work is standard-rated at 20%, which a VAT-registered business can usually recover, so the honest way to compare quotes is to work in figures excluding VAT. A standalone carport is not expressly covered by HMRC guidance, so the treatment should be confirmed per project rather than assumed. We quote commercial work excluding VAT and explain the mechanics on the cost page.
The second inflated claim is that solar qualifies for 100% full expensing. It does not. Solar PV is classed as special-rate plant and machinery, which is excluded from full expensing and from the 40% main-rate first-year allowance. What it can use is the Annual Investment Allowance, relieving 100% of qualifying spend up to £1m, plus the permanent 50% first-year allowance available to companies. Those are useful, but they are not full expensing, and the difference matters when you model cash flow. We set out the mechanism, with the caveat to take your own tax advice, on our capital allowances page. One more point often confused: solar is exempt from business rates in England only, to 31 March 2035, not in Wales or Scotland.
Price and payback: a carport is not a roof
The engineering myth is that a carport costs about the same as a rooftop array. It cannot, because a carport carries its own steel. That structure is typically 40 to 50% of the total, which is why carports run about £1,100 to £1,600/kWp at scale (more like £1,200 to £3,000/kWp on smaller schemes) against roughly £700 to £1,050/kWp on a roof, or around £6,000 to £12,000 per parking space excluding VAT. That premium feeds straight into payback. At UK yields of about 900 to 950 kWh/kWp, a carport of roughly 2 kWp per bay generates in the region of 1,700 to 2,000 kWh a year, and solar-only payback lands around 8 to 10 years. Claims of a three-year payback quietly drop the structure cost from the sum. The premium buys you covered parking, resilience and a ready platform for EV charging, so a carport earns its place where those matter, not as a cut-price route to capacity.
Timescales and competence
Finally, the idea that a commercial system goes in over a few days. The build itself can be quick, but most commercial arrays exceed 3.68kW per phase, which triggers a G99 connection application to the distribution network operator. That process commonly takes 8 to 16 weeks before you are allowed to energise, and it runs in parallel with structural design and any prior approval. Only genuinely small, sub-3.68kW single-phase installs use the lighter G98 notification. This is also why a general electrician is the wrong call: a carport is a structural build married to a grid-tied PV system, needing foundation and structural design, MCS-standard workmanship and G99-competent electrical engineering. That combination is the whole point of using a carport install specialist rather than a generalist. When you are ready for real figures against your own parking layout, request a quote.