Solar carport installers: how to choose the right one

A solar carport is not a bigger rooftop job. It is a small building with a power station on top, and the firm you hire has to be competent across trades that rarely sit under one roof. Get the selection right and you have one accountable contractor from foundations to first export. Get it wrong and you end up project-managing a steel fabricator, a groundworks gang and an electrician who have never worked together, with no one owning the whole. This page is about how to vet that competence properly, rather than picking the cheapest logo off a search result.

A solar carport spans three trades, not one

Most enquiries treat a carport as a solar decision with a frame attached. In practice the frame, the ground and the grid usually cost more and carry more risk than the panels. A credible installer has to demonstrate genuine capability in all of the following, or a managed supply chain that they are contractually accountable for:

• Structural steel. The canopy is an engineered structure carrying wind uplift and snow load. It must be designed to BS EN 1991 (loading) and BS EN 1993 (steelwork), fabricated to spec and signed off. This is an engineering discipline, not a kit assembly.
• Groundworks and foundations. Every bay stands on a foundation. Whether that is a driven or screw pile or a cast concrete footing depends on your ground, not on what the installer happens to own. Made ground, contamination, high water tables and buried services all change the answer.
• MCS-certified PV. The generation side must be installed by an MCS-certified contractor with the electrical qualifications behind it. MCS certification of the installed system is what makes the site eligible for the Smart Export Guarantee (SEG); without it, most suppliers will not pay for your export.

Sitting across all three is the DNO grid connection. Anything above 3.68 kW per phase, which covers virtually every commercial carport, needs a G99 application to your Distribution Network Operator, and that process often runs eight to sixteen weeks. Someone has to own that application from day one. If no one names it early, it becomes the thing that delays your energisation after the steel is already up. Our guide to how solar carports are installed walks the full sequence, but the vetting question is simpler: who, by name, is responsible for each of these four workstreams?

What the accreditations actually mean

Badges get listed on websites without much explanation of what they cover. Here is what each one genuinely tells you, and what it does not.

• MCS certification. Covers the PV installation to a defined standard and unlocks SEG eligibility. It says nothing about the steel or the foundations. An MCS certificate is necessary, not sufficient, for a carport.
• NICEIC or NAPIT. Competent-person schemes for the electrical work, giving you compliant certification against BS 7671 (the 18th Edition wiring regulations). This is the electrician's credential, separate from MCS.
• Structural engineer sign-off. A named, chartered or incorporated engineer who takes responsibility for the canopy design against the loading and steelwork standards. On a carport this is the credential that is most often missing and matters most. Ask to see it as a deliverable, not a promise.
• CDM 2015 principal contractor. A carport with more than one trade on site is a construction project under the Construction (Design and Management) Regulations 2015. Your appointed principal designer and principal contractor carry legal duties for planning and safety. A firm that cannot explain its CDM role is telling you it does not run projects of this size.
• RECC and TrustMark. Consumer-protection codes designed for domestic work. A standalone commercial carport typically runs under a construction contract rather than consumer terms, so treat these as evidence of a mature process and good workmanship insurance, not as the governing framework for your job.

The questions that separate an installer from a broker

Anyone can subcontract a carport. The point of vetting is to find out how much they genuinely control. Ask these, and listen for specific answers rather than reassurance:

1. Who does the structural design, and will I get a signed engineer's calculation? The right answer names a person or firm and offers the calculation as a deliverable. A vague "our supplier handles that" means no one on your side owns the structure.
2. Screw pile or concrete footing, and why for my site? A competent installer answers with reference to your ground conditions, water table and any contamination, not to a default. Screw piles are quick and reversible; mass concrete suits poor or made ground. If the answer never changes site to site, they are selling a kit.
3. Who submits and manages the G99 application? You want a named owner and an honest timeline of eight to sixteen weeks, started early. If the DNO process is treated as an afterthought, expect a finished carport that cannot export.
4. Is this one contract or several sub-let packages? One contract means one firm is liable if the steel, the roof waterproofing and the inverter do not agree with each other. Multiple contracts push that coordination risk onto you.
5. How is the warranty split between structure and panels? Steel, waterproofing, inverters and modules carry different warranty terms from different manufacturers. Ask who you call for each, and who is liable if a roof leak damages the electrical work below.

Red flags worth walking away from

Some signals reliably predict a job that goes wrong. Treat any of these as a reason to keep looking:

• A frame-only quote sold as an installation. If the panels, the electrical connection and the grid application are quietly "left to you", you are not comparing like with like against a turnkey price.
• No MCS certification for the PV. Without it your export income under SEG is at risk, and it usually indicates the solar is being subcontracted to whoever is cheapest that month.
• No structural sign-off offered. A carport with no named engineer behind the loading calculations is an uninsurable liability. If they cannot produce the calculation, they have not done it.
• A single headline price with no breakdown. Steel is typically forty to fifty per cent of a carport's cost. If that split is hidden, you cannot tell where corners are being cut.