How a solar carport is installed, step by step

1. Site survey and feasibility

Every installation starts on the ground. A surveyor measures the car park, counts usable bays and sets out a canopy layout that keeps aisles, turning circles and disabled bays workable. The survey also captures four things that decide whether the project is buildable: ground conditions, grid capacity, shading and expected yield.

Ground conditions are checked with trial holes (trial pits) so the engineer can see what lies beneath the surface, made ground, bearing capacity, buried services and any obstructions, before anyone commits to a foundation type. Grid capacity is assessed from the existing supply, metering and spare headroom at the connection point. A shading study accounts for buildings, trees and lighting columns. From that, we estimate output: UK yields run at roughly 900 to 950 kWh per kWp a year, and a typical two-panel-per-bay canopy of around 2 kWp per bay generates in the region of 1,700 to 2,000 kWh per bay each year. Solar-only payback on a carport is commonly in the eight to ten year range.

2. Structural and electrical design, plus a fixed line-item quote

The canopy is designed as a load-bearing structure. Wind and snow loading are calculated to BS EN 1991 (Eurocode 1) and the steelwork to BS EN 1993 (Eurocode 3), so the frame carries the array plus environmental loads at your specific site. The trial-hole results feed foundation selection at this stage rather than being discovered on site. In parallel, the electrical design fixes inverter sizing, string layout, cable routes, protection and metering.

You should receive a fixed, itemised quote at the end of design, not a rate per kW with surprises later. Structural steel is the single largest line, commonly 40 to 50 per cent of the build cost, which is why a carport typically costs around two to three times a rooftop array of the same size. Commercial quotes are given excluding VAT (charged at 20 per cent and normally recoverable). The full breakdown, including how price scales with size, is set out on our solar carport cost page.

3. Planning and grid connection, run in parallel

Planning and the grid application start together, because the grid queue is often the longer pole. On the planning side the route depends on where you are:

• England. Non-domestic solar canopies fall under Class OA permitted development (in force from 21 December 2023). This is prior approval, not full planning: the council reviews siting, design and glare only. The canopy must be no more than 4 m high, sited more than 10 m from a dwelling, and must not be on listed or scheduled sites or carry advertising. The council determines it within 56 days. Surface-water run-off (SuDS) is handled as a mandatory condition, not as one of the prior-approval matters. It is a standing right, so there is no deadline to apply, but the works must be completed, not merely started, within three years.
• Scotland. Under Class 9M (SSI 2024/102, in force 24 May 2024) the canopy itself is permitted development outright; an associated battery is dealt with through a prior-approval notification.
• Wales and Northern Ireland. Full planning permission is generally required and is assessed case by case.

Domestic canopies follow a different set of Class E limits again. The routes, height caps and conditions are explained in full on our solar carport planning permission guide.

The grid application runs to the distribution network operator. Small systems up to 3.68 kW per phase use the G98 connect-and-notify route; anything above that, which covers most commercial carports, needs a G99 application and approval before energising. G99 approvals commonly take eight to sixteen weeks, so this is submitted as early as possible.

4. Fabrication and procurement

Once design is signed off and applications are in, the steel is fabricated and the main components are procured. Carport frames are made from hot-dip galvanised structural steel so they hold up outdoors for a 25-year-plus design life without rusting at the joints. Modules, inverters, mounting rails and cabling are ordered against the design. Fabricating the frame in a factory keeps on-site time, and disruption to your car park, to a minimum.

5. Groundworks and foundations

Foundations are chosen from the ground survey, not by default. There are three common routes:

• Helical screw piles. Wound into the ground, fast to install, low spoil and removable at end of life. Suited to reasonable ground conditions.
• Concrete footings. Pad-and-pier or mass concrete, used for heavier loads or where ground is weaker and needs a broader bearing.
• Ballasted or surface-mounted bases. Used where you cannot or should not dig, for example over contaminated ground, membranes, shallow services or existing hard standing you want to keep intact.

Groundworks include any excavation, base pours and the surface-water drainage that ties back to the SuDS condition. This is where those trial holes from stage one pay for themselves: the right foundation is priced and built once.

6. Steel erection and canopy build

With foundations cured or set, the frame goes up: columns, beams and purlins, followed by the mounting rails and modules. On a live car park this is phased bay by bay so most of the spaces stay open while a section is worked on, with traffic management keeping vehicles and the crew apart. The canopy is weathered and the array laid out ready for connection.

7. Electrical work, testing and commissioning

All DC and AC wiring, inverters, isolators and metering are installed and tested to BS 7671 (the 18th Edition wiring regulations). The installation is completed under MCS so it can be certified, which matters for export arrangements and finance. After in-house testing, the system is commissioned; for a G99 connection this includes the DNO witnessing or signing off the connection before the array is energised. Commercial export is usually sold through a power purchase agreement rather than a fixed feed-in rate.

8. Handover, warranties and ongoing maintenance

At handover you receive the commissioning certificates, MCS paperwork, electrical test results, a monitoring login and the operation and maintenance manual. Warranties are itemised by component, workmanship on the installation, plus separate inverter and panel performance warranties, so you know exactly what is covered and for how long. A short maintenance and cleaning schedule keeps the array performing; because a carport array sits at a shallow angle over a car park, periodic cleaning matters more than on a steep roof.

How long does a solar carport installation take?

The critical path is usually the grid connection, not the build. Because planning and the G99 application run alongside design and fabrication, the visible on-site work is a small slice of the overall programme. Sites vary: the layout for a school, a retail park or a fleet depot each changes the survey and phasing, which we cover across our carport solutions by sector.