Car Park Solar Panels: Sizing, Yield and Approvals

Car park solar panels are Tier-1 bifacial photovoltaic modules mounted on a steel-frame structure above a commercial car park — combining vehicle shelter, electricity generation and EV charging in a single installation. UK demand for car park solar panels has grown with MEES compliance deadlines and Workplace Charging Scheme incentives. Unlike rooftop PV, car park solar panels generate from both faces of the module — the front face collects direct sunlight; the rear face collects reflected irradiance from the tarmac below, adding 5–12% extra annual yield.

Panel selection drives both yield and per-kWp cost. Per-bay output: 1.5 kWp typical (using ~3 × 545W panels per single-bay carport). String configuration: optimisers (SolarEdge) or microinverters (Enphase) for shaded sites; string inverters (SMA, Sungrow, Huawei) for uniform layouts.

What a car park's own numbers look like

A commercial canopy carries roughly 1.5 kWp per standard parking bay, so the array size follows the bay count rather than any sales band: 100 bays is about 150 kWp, 200 bays about 300 kWp, 500 bays about 750 kWp. What that array then generates depends on where the car park is, and the spread across the UK is wider than most business cases allow for.

Canopies sit at a shallow pitch — around 10 degrees, because a steeper tilt costs headroom and wind load — so the right yield figure is the shallow-tilt one, not the 35-degree rooftop number. At 10 degrees facing south, PVGIS gives roughly 920 kWh/kWp in London, 946 in Cardiff, 807 in Manchester and 772 in Glasgow. A 300 kWp canopy over 200 bays therefore generates about 276,000 kWh a year in London and about 232,000 kWh in Glasgow — a 16% swing on identical steel and identical panels.

That single difference moves payback by more than any discount a supplier will offer, which is why the location figure belongs in the model before anyone is asked to quote.

Every commercial car park array is a G99 connection, not G98

There are two connection routes for UK generation, and car park solar only ever uses one of them. G98 is the notify-after-connection route, and it stops at 16 A per phase — about 3.68 kW per phase, so roughly 11 kW on a three-phase supply. Every figure in the section above is an order of magnitude past that ceiling.

So a car park array is a G99 application: the DNO assesses it before anything is connected, and the answer can come back as a connection offer with a cost attached, a curtailment condition, or a queue position. The ENA's Distributed Generation guide (March 2026, V3.0) sets out the route. Two practical consequences: start the G99 application in parallel with planning rather than after it, because the grid answer is the one most likely to change the scheme; and ask the DNO about export limitation early, because a site that can only export a fraction of its generation is a self-consumption project, which changes the panel count and the business case.

Any quote that mentions G98 for a car park has misread the thresholds, and that is a useful first filter on a supplier.

Planning: Class OA and the 56-day clock — England only

In England, a canopy over an existing off-street car park is permitted development subject to prior approval under Class OA, with a height limit of 4 metres. Prior approval is not the same as a full application: the authority has 56 days to determine it, and if it does not, approval is deemed. That clock is the single most useful number in the programme, because it is the one date a car park owner can plan around.

Class OA does not travel. Wales has no equivalent right — its stand-alone solar permitted development caps at 9 square metres, which no car park canopy will meet, so a Welsh scheme is a full planning application every time. Scotland and Northern Ireland run their own regimes. Listed buildings, conservation areas and sites under an Article 4 direction can also remove the right, and Article 4 directions vary street by street, so the council's own list is the only reliable check.

Where prior approval applies, the submission still has to carry the structural, drainage and visual-impact detail — a thin submission is how a 56-day route turns into a refusal.

The tax position, and the one claim to stop repeating

Car park solar is special-rate plant for capital allowances. The usable relief is the Annual Investment Allowance: 100% of qualifying plant in year one, up to £1m. Two claims are commonly made and both are wrong: solar cannot claim full expensing, and it is not general-pool plant either. Getting that wrong overstates the year-one benefit in a capital paper.

On the holding side, on-site renewables plant is out of rateable value in England until 2035, so the canopy does not raise the rates bill on the site it serves. For the charging hardware — not the canopy — the OZEV Workplace Charging Scheme contributes £500 per socket (raised from £350 on 1 April 2026), or £2,000 per socket for state-funded schools, to a 40-socket cap, so £20,000 at the cap.

For public-sector sites, the Public Sector Decarbonisation Scheme is closed — Phase 4 was the final phase and shut to new applications in November 2024 — so a council or NHS car park is funded from capital, prudential borrowing or a PPA, with the saving and the export value carrying the case. Full detail on both tax lines sits on capital allowances on a solar carport and business rates on a solar carport.

Why so few car parks have solar, and what the government decided

Sunlight is rarely what stops a car park scheme. The blockers are ownership and lease length, daytime demand, the G99 grid route, ground conditions and capital cost, and why more UK car parks do not have solar panels ranks them in the order they tend to decide a project. On 21 May 2026 the government also recorded that it will not take forward a solar canopy mandate at this point, so any scheme has to stand on its own economics: the mandate update sets out what was decided and what Class OA still allows in England. If the site also needs lighting, solar car park lighting explains why December, not June, sizes standalone solar lights.