The best question to ask a solar installer is whether they are MCS certified, and to ask for the certification number. You can check it online in a few minutes, and that one step protects your right to export payments and screens out many weak firms.

After that, ask about the quote itself, the roof, the paperwork, the warranties and the payment terms. This guide gives you the questions, explains why each one matters, and shows what a good answer sounds like. The facts are current as of October 2026.

Start with certification

Ask first: “Are you MCS certified for solar PV, and what is your certification number?” Then check the answer on the MCS installer search. The search lets you look up a firm by name or number. It shows the certification body and approved technologies.

This matters because the Smart Export Guarantee needs it. For example, GOV.UK says you must show that your installation and installer are certified through MCS or an accredited equivalent. Our guide to MCS certification explains what the badge covers.

Also ask which consumer code the firm belongs to. Most MCS installers belong to one approved by the Chartered Trading Standards Institute, such as RECC or HIES. However, MCS rules on this are changing, so ask the question directly, because the code sets your complaint route.

Ask about your roof and your site

A good installer looks at your roof before quoting a final price, because roofs differ. Ask who will visit, and what they will check. Ask how they judge shade, pitch, direction and roof condition.

These questions test the survey.

  • Will someone visit my home, or is the quote based on a satellite image?
  • How will you place the panels, and why that layout?
  • Is my roof strong and in good repair for the panels?
  • Do you need scaffolding, and is it in the price?

Our hub on roof and property suitability explains what affects the layout. Also, if your roof is flat or faces east and west, read east-west and flat roof solar panels first. Then ask the installer how they would handle it.

Ask about planning and permissions

Most roof panels in England do not need planning permission. However, listed buildings and some conservation area walls do. Ask the installer who checks this, and who applies if you need permission. See do solar panels need planning permission for the rules.

Ask about the grid too, because the paperwork is easy to forget. Your installer should deal with the network operator. For a small system, MCS says the operator needs notifying within 28 days of commissioning. Larger systems need approval first. Ask which route applies to you.

Our hub on how to plan a solar installation lists the steps in order.

Ask about price, VAT and what the quote includes

Quotes are easy to misread. For instance, one firm may price scaffolding, the inverter and the paperwork inside the total. Another may add them later. So ask for a written breakdown.

Ask these questions about money.

  1. What exactly does the price include?
  2. Does the price include 0% VAT, and how is that shown?
  3. What is the payment schedule?
  4. What would raise the price after the survey?

The zero rate for installed solar panels and batteries runs until 31 March 2027 (it began on 1 April 2022 in Great Britain and 1 May 2023 in Northern Ireland), according to GOV.UK VAT Notice 708/6. The rate then goes to 5%. The relief applies where the person who installs the materials supplies them, so buying panels alone does not qualify. Our post on 0% VAT on solar panels and batteries explains the detail.

For typical prices, read how much solar panels cost. Treat any single “average” with care. Our hub on solar panel costs and savings explains how size and roof change the figure.

Ask about deposits and cancellation

Money terms deserve the most care, because mistakes here cost the most. The Renewable Energy Consumer Code advises you never to pay more than 25% of the price up front. It also says to check that the deposit will be protected. Ask how the firm protects it, and ask for the answer in writing.

The same guidance describes a 14-day right to cancel from signing. If you want work to start during that time, you must give express written consent. You would then pay for work done if you cancel. So do not agree to an early start unless you are sure.

Be wary of pressure. Instead, note that the code’s tips say to decline pressure tactics and signing incentives. A fair firm lets you take the quote home.

Ask about equipment and warranties

First, ask for the make and model of the panels, the inverter and any battery. Then look up the warranty terms. Ask who honours each warranty if the firm closes. Ask whether there is a workmanship guarantee, and how long it lasts.

Also ask about upkeep. Panels need little care, but they are not zero-maintenance, so ask what the installer advises for cleaning and checks. Our guide to cleaning and maintaining solar panels explains what is sensible.

Ask about “free” and finance offers

Some firms offer “free” panels or finance. These can be genuine, but they often come with long contracts. Therefore, ask who owns the panels, who gets the export payments and what happens if you sell the house. Read free solar panel schemes explained before you sign.

Grants vary by nation and change often, so check the current official page, not a sales call. For example, MCS says ECO4 is due to close on 31 December 2026.

What to do after the answers

Compare at least three quotes, because the consumer code’s tips say the same. Check each firm on the MCS register, and compare the same system size and equipment. Then choose the clearest, not just the cheapest, because clear terms prevent disputes.

Our hub on choosing a solar installer pulls these checks together. If something goes wrong later, keep every email. MCS has a three-step complaints route, set out in our MCS guide.

Sources

Common questions

How many solar quotes should I get?

Get at least three. The Renewable Energy Consumer Code advises this. Compare the same system size, panel and inverter models, and what the price includes.

What is the most important question to ask a solar installer?

Ask if they are MCS certified and ask for the certification number. You can then check it on the MCS website. Without MCS, or an accredited equivalent, you cannot usually claim Smart Export Guarantee payments.

How much deposit should I pay for solar panels?

The Renewable Energy Consumer Code advises never paying more than 25% up front. Check that the deposit is protected before you pay. Ask in writing how it is protected.

Can I cancel a solar contract after signing?

You normally have a 14-day cancellation right if you sign at home or at a distance. Starting work during that time needs your written consent. Read the cancellation terms before you sign.

What are the red flags in a solar quote?

Be wary of pressure to sign today, big discounts that expire, and vague system details. Also be wary of a firm that cannot show an MCS listing. Walk away if answers are unclear.