Start with the installer, in writing
Whatever the problem, the first step is the firm that did the work. RECC's advice is to contact the installer in writing as soon as possible and give it the opportunity to put things right (RECC), and MCS says the same: contact the installer first, explain the problem and say what you would like to happen (MCS). A letter or an email gives you a dated record that a phone call does not.
Put the facts in one place. Say what is wrong and when you first noticed it, attach photographs taken from the ground or the garden, and quote the contract or quote reference. For a fault in output, give the readings: what the system made in recent months, in kWh, against the monthly figures in the written estimate. MCS adds that response times vary, but that 14 days is a reasonable maximum time to expect a reply (MCS), so name a date by which you expect an answer.
Output complaints need care, because one dull month proves very little. PVGIS, the European Commission's solar model, puts a south-facing roof at 35° in central Wigan at 927 kWh per kW a year, averaged over 2005-2023, and the 12 places it was run for across the borough range from 911 kWh in Atherton and Tyldesley to 936 kWh in Orrell (PVGIS 5.3). Compare a full year, or the same months year on year, against the installer's estimate and those figures. Output across the borough has every direction, and the quote checker will test the original estimate.
The consumer code: RECC or HIES
If the installer belongs to a consumer code, the code's rules become your checklist. RECC says its membership comes with requirements around contracts, deposits, warranties and complaints, and that every member must give a workmanship warranty of at least two years, covering problems caused by incorrect installation, with financial protection if the installer fails to put an issue right or stops trading (RECC). If the installer does not resolve the problem, RECC says you may be able to make a formal complaint, and its members give customers access to Green Homes Dispute Resolution, an independent service at no cost to the consumer (RECC; Green Homes Dispute Resolution).
HIES runs a code too, and says its members operate under a consumer code approved by the Chartered Trading Standards Institute (HIES). For a complaint about one of its members, its site asks you to follow its complaints procedure through an online form, and it publishes the rules of its alternative dispute resolution scheme (HIES). Its pages did not set out step-by-step timescales when this guide was checked, so read the scheme rules before you start and keep a copy of everything you send.
Which code applies should be on the quote and the contract. If it is not, ask the firm, then check its membership on that code's own site.
MCS: complaints and certificate queries
MCS runs its own complaints process. If the installer does not resolve the issue, you can escalate it to MCS through the online form on its site; MCS says it will acknowledge a complaint within 5 working days, update you at least every 10 working days, and that most complaints should be fully resolved within 8 weeks. It may carry out a technical review and works with the installer towards a resolution, then sends a written decision with its reasons (MCS).
If you are still unhappy, the complaint becomes a dispute, which MCS says it is not accredited to resolve itself. Its partner for that stage is the Dispute Resolution Ombudsman, operating as the Furniture & Home Improvement Ombudsman, funded by MCS and at no cost to you for an eligible dispute. You can take it there within 12 months of MCS concluding the complaint, or once it has gone unresolved for 12 weeks, provided the contract qualifies: one made under MCS's redeveloped installer scheme, or under the original scheme on or after 1 January 2025 where the installer has agreed in writing. For a contract made before 1 January 2025, the route to dispute resolution runs through the installer's consumer code, RECC or HIES (MCS).
The MCS certificate is a separate question. MCS says the installer must issue it within 14 days of the system being commissioned, or 30 days if the installer is certified under its redeveloped scheme. MCS cannot raise a missing certificate for you, and for a copy or a correction it asks you to go to the installer first; it supplies copies or makes amendments itself only where the installer is no longer certified or no longer trading (MCS).
Your rights under the Consumer Rights Act
Behind every installation contract sits the law. Section 49 of the Consumer Rights Act 2015 says every contract to supply a service is to be treated as including a term that the trader must perform the service with reasonable care and skill (legislation.gov.uk). Where the work falls short, section 55 lets you require the trader to perform it again, as far as needed to put it right, within a reasonable time, without significant inconvenience to you and at the trader's own cost, labour and materials included (section 55). Section 56 sets out a separate right to a price reduction (section 56).
What the firm told you counts as well. Under section 50, anything said or written to you by or for the trader about the trader or the service becomes a term of the contract if you took it into account when deciding to sign, or when making a later decision about the service (section 50). That is why the written performance estimate, the quote and any promises in emails are worth keeping: they are the measure the finished job is held against.
Name the section in your letter if the firm stalls. You do not need a solicitor to do that, and it shows the firm you know the standard it is held to. Arguments about the price itself, such as extras added after signing or a bill well above the quote, are easier to make with the North West figures on the costs page and the itemised lines described in what a quote should include.
Deposits, and a firm that stops trading
The hardest case is a deposit paid and a firm gone quiet, or gone altogether. This is where the consumer code earns its place: RECC lists deposits among the matters its membership rules cover, and its workmanship warranty comes with financial protection if the installer ceases trading (RECC). HIES lists deposit and stage payment protection among its pages for homeowners (HIES). Before paying anything, ask who protects the deposit and get the document that says so; afterwards, it is the first thing to find.
If the firm has stopped trading, contact the code it belonged to, and ask MCS for a copy of the certificate if you never received one or have lost it, which it can supply when the installer is no longer trading (MCS). Check the handover pack for the manufacturers' warranties on the panels and the inverter, and for how to claim on them; looking after solar panels covers which papers to keep together.
| Problem | First step | If it is not settled |
|---|---|---|
| Output well below the written estimate | Write to the installer with a year of readings against the estimate | The consumer code's complaints route, or MCS |
| A leak or damage to the roof after the work | Write to the installer with photographs and dates | The consumer code; section 55 of the Consumer Rights Act |
| MCS certificate missing or wrong | Ask the installer, which must issue it within 14 days of commissioning | MCS, once the installer is no longer certified or trading |
| Deposit paid, no work, no reply | Write with a deadline; find the deposit protection document | The consumer code, then whoever protects the deposit |
| The firm has stopped trading | Contact its consumer code | MCS for a copy certificate; the manufacturers' warranties |
| Work you never agreed to, or a refused cancellation | Put it in writing and keep copies | Wigan Council's Trading Standards team |
When it is a matter for Trading Standards
Some problems are less about quality than about conduct that may be unlawful: pressure at the door, work started that you never agreed to, or a cancellation a firm refuses to accept. Wigan Council's doorstep crime page says the most vulnerable people in the community are often targeted by traders who persuade them to have work done, and asks residents to report unwanted callers to the council or to Greater Manchester Police (Wigan Council).
Doorstep sellers covers the cancellation rules in detail. And if you have not yet chosen a firm, the checks on checking a solar installer are the cheapest way to make most of this page unnecessary.