Before you hire a commercial solar installer, get clear answers to twelve questions. They cover who will do the work, whether they are insured, what they have built before, how they price the job, and what they will do if something goes wrong. A good installer will answer all of them in writing and without fuss. If the answers are vague, treat that as information.
Each question below comes with what a good answer sounds like and what should worry you.
1. Who will actually carry out the work?
Many firms sign the contract and then use subcontractors. That is not wrong, but you should know. Ask who designs the system, who installs it, who commissions it and who is on site day to day. A good answer names the people and the firms, and says who is responsible if a subcontractor fails.
2. What accreditations do you hold, and what do they cover?
MCS describes itself as the UK’s quality mark for small-scale renewable technologies. Check the scope of any scheme against your project size, because a scheme built for small systems may not cover a large commercial one. Ask for the certificate number and check it with the body that issued it. Do not rely on a logo on a website.
Also ask which electrician and trade bodies the firm’s staff belong to, and how the firm is assessed for competence on larger roofs.
3. What insurance do you carry?
Employers in Great Britain must hold employers’ liability insurance of at least £5 million, and can be fined £2,500 for every day they are not properly covered. Ask to see the certificate. Ask too about public liability and professional indemnity, and what the limits are. Compare the limits to the value of your building, not just to the job.
A good answer is a certificate sent the same day. A poor answer is a promise to find it later.
4. Who handles the grid application?
For most commercial systems the network operator must approve the connection. Our guide to G99 explains the steps. Ask who applies, who pays any network costs, and what happens if the operator says no or asks for upgrades. Check that the price covers these things, or says clearly that it does not.
5. Have you checked my roof?
A roof must carry the panels, the wind loads and the people who maintain them. Ask whether a structural check is included and who does it. Our post on roof surveys, loading and asbestos explains why. If the roof may contain asbestos, the work needs a plan before anyone touches it.
A quote issued without a site visit or a survey is still a rough estimate, not a price.
6. Who manages health and safety on the project?
Most solar installs are construction work. Under the Construction (Design and Management) Regulations 2015, a commercial client must appoint a principal designer and a principal contractor when more than one contractor is involved, and must make sure a construction phase plan is in place. Ask who will take on these roles and how they work at height.
7. What exactly is in the price?
Ask for a line-by-line quote. It should show panels, inverters, mounting, cabling, scaffolding or access, commissioning, monitoring, grid costs, and any batteries. Check what is excluded. Check the VAT treatment, since commercial buildings pay standard-rate VAT for most projects.
Two quotes are only comparable if they list the same kit and the same exclusions.
8. What are the performance figures based on?
Installers often quote the yearly output a system should produce. Ask what site data and software they used, what shading and roof angle they assumed, and what loss figures they applied. Ask what the number means if the system falls short.
Be careful of a figure that sounds too good. Our guide to feasibility studies shows what a careful assumption set looks like.
9. What warranties do I get, and who stands behind them?
There are usually three: the product warranty for panels, the one for inverters, and the installer’s workmanship warranty. Ask for each in writing, with the length and the claim process. A manufacturer’s warranty is only worth the manufacturer’s survival, so ask who honours it if the maker goes under. Our guide to degradation and warranties explains how to read them.
10. Can I speak to previous clients?
Ask for references on projects of a similar size and type, and ring them. Ask whether the job finished on time, how problems were handled, and whether the system has produced what was promised. Be wary of case studies without names, since you cannot check them.
11. Who looks after the system afterwards?
Ask what monitoring is included, who watches it, and what happens when output drops. Ask whether there is a maintenance offer and whether you are free to use another firm. Our post on maintenance contracts shows what a decent agreement contains.
12. How is payment structured?
Staged payments tied to milestones are normal. Large payments up front are a risk, especially from a small firm. Ask what happens to your money if the installer goes bust partway through, and what security the contract gives you.
What a good answer looks like
- It is specific, with names, numbers and documents.
- It is written down.
- It tells you what is excluded as well as what is included.
- It does not rely on pressure, such as a price that ends today.
Do you need someone on your side?
Many buyers rely on the installer to design and price the job. That is understandable, but it puts the seller in charge of the specification. Our post on independent advisers versus installers looks at the difference. We are an independent adviser, so we have no panels to sell. Our procurement and tender support service writes the brief, collects like-for-like bids and scores them, and our feasibility studies come first if you are still deciding whether to go ahead.
Sources: MCS; GOV.UK, employers’ liability insurance; HSE, CDM 2015 commercial clients.
These questions work best inside a fair tender, because every installer then answers the same ones. Our procurement and tender support builds them into the specification. A feasibility study gives you the yield and roof facts to test answers against, while energy and ROI modelling checks each price. For funded offers, PPA and financing advice asks the same questions of the funder.