Questions to ask a solar installer before you sign
A solar quote is only as good as the questions behind it. The right ones flush out corner-cutting, vague warranties and optimistic savings before you commit thousands of pounds. The good news is that a confident, competent installer welcomes them; the ones who get evasive are telling you something. Here are the questions worth asking, grouped by what they protect, with a note on the answer you're listening for.
Accreditation and accountability
- What's your MCS certification number? You can check it on the MCS register. No number, no export payments, as explained in what is MCS certification.
- Which consumer code are you in? Expect RECC or HIES, which brings deposit protection and an insurance-backed guarantee.
- Who actually carries out the installation? If the work is subcontracted, ask who holds the workmanship guarantee and who you call for aftercare.
The kit and its warranties
- Which panels and inverter, and what are the warranties? Look for a product warranty plus a longer performance warranty on the panels, and a clear figure on the inverter, which is the part most likely to need replacing in years 10 to 15.
- Is a battery included, and is its cost shown separately? You want to judge the battery on its own merits, the way are solar batteries worth it sets out, not buried in a bundle.
- What happens if a panel or the inverter fails? Who pays for labour as well as parts, and for how long.
The performance estimate
- How did you calculate the generation and savings figures? A proper estimate uses the MCS methodology, factoring in your roof's orientation, pitch and shading, not a round number. Inflated, unexplained savings are the warning sign covered in solar panel myths.
- What self-consumption rate have you assumed? This single assumption swings the savings a lot, as solar panel payback explains. If they've assumed you use most of your generation but you're out all day, the figure is too rosy.
The install itself
- Who handles the DNO grid connection? The installer should notify or apply to your Distribution Network Operator (a G98 notification for most domestic systems, a G99 application for larger ones). You shouldn't have to chase this.
- Is scaffolding included in the price? A common hidden extra. Get it in writing.
- How long will the work take, and when can you start? A realistic timeline beats an implausibly quick one.
- Will you register the system and provide the MCS certificate and DNO paperwork? You need these to claim the Smart Export Guarantee.
The money and the paperwork
- How much deposit, and is it protected? Deposit protection should come with the consumer code. Be wary of large upfront payments.
- What does the workmanship guarantee cover, and is it insurance-backed? So it survives the installer going out of business.
- Can I have the full quote in writing, itemised? Then read it the way how to read a solar quote describes before comparing.
The detail most people miss
Ask what happens at the handover. A good installer walks you through the monitoring app, shows you the isolator switches, and leaves you the full document pack: MCS certificate, DNO confirmation, electrical certificate, and the warranties. That pack is what you'll need years later to make a warranty claim or to satisfy a buyer's surveyor if you sell. An installer who treats handover as an afterthought often treats aftercare the same way.
Frequently asked questions
Ask for the MCS number and consumer code, the panel and inverter brands and warranties, how the savings were calculated, who handles the DNO connection, whether scaffolding is included, and what the workmanship guarantee covers.
A good quote is itemised, names the exact kit and warranties, shows how the savings were worked out, includes scaffolding and the grid connection, and comes from an MCS-certified installer in a consumer code.
Ask for the panel product and performance warranties, the inverter warranty, whether labour is covered as well as parts, and whether the workmanship guarantee is insurance-backed.
The installer. Most domestic systems need a G98 notification to your Distribution Network Operator; larger ones need a G99 application. You shouldn't have to do this yourself.