How to check a solar panel quote before you sign

Check your quote with our tool

Enter up to three quotes. The tool works the two sums below, checks the battery price, deposit, VAT and grid points, and turns anything missing into questions you can copy and send back. It compares and asks; it does not judge whether a price is fair.

What should a solar quote include?

MCS, the certification scheme for installers, publishes guidance on what a quotation should contain [1]. Its list includes:

• the installer's business name, contact details and MCS certification number, and its company registration number and VAT number where they apply
• a full breakdown of the work and of the cost (labour, materials, equipment)
• the make, model and performance of each product
• the price before VAT, the VAT and the total
• how long the job will take and when it can start
• any deposit, staged payments and how a deposit is protected
• guarantees and warranties, with how long they last, and how long the quote is valid [1]

Installers under MCS's redeveloped scheme also commit to telling you about any additional work and its cost at the quotation stage [3].

An MCS installer should also give you, in writing, a performance estimate in MCS's standard format, the datasheets for the panels, inverter and any battery, and a drawing of the panel layout. The redeveloped scheme says before the contract; the current one says at or before it [2][13]. The estimate must say it is not a guarantee of performance [2][13].

A worked example, line by line

This quote is made up to show the method; its prices are not typical or recommended. Read the right-hand column against your own quote.

How do you compare solar quotes?

With two sums, each a division.

1. Pounds per kWp. Take the solar part of the price and divide it by the total kWp. In the example, £7,950 for 5.40 kWp is £1,472 per kWp (our calculation). The government's figures for MCS installations on existing homes in 2025/26 averaged £1,651 per kW of total installed capacity (TIC) for 4 to 10 kW systems and £2,109 up to 4 kW [4]. We treat a quote's kWp as its installed capacity, as our cost page does.

The DESNZ figures include equipment, installation, connection and VAT where it applied, and leave out batteries, extended warranties and any other material or works carried out on the solar equipment [4]. Take batteries and extended warranties out of your quote first; where an extra such as bird mesh may count as other material, do the sum with and without it. These are averages across Great Britain, so a fair quote can sit above or below them.

Labour, scaffolding and a hybrid inverter can serve both the panels and the battery. If your quote does not split them, work the sum both ways: in the example, moving half the installation cost to the battery gives £1,259 per kWp instead of £1,472 (our calculation). More on prices by size is in solar panel cost.

2. kWh per kWp. Divide the estimated yearly output by the total kWp. The MCS estimate is kWp times a figure from MCS's table for your postcode zone, roof pitch and direction, times a shade factor [2]. So for panels on the same roof faces, two MCS standard estimates should give a similar kWh per kWp unless they assumed different pitch, direction or shade, or assessed shade by a different method. Under the current scheme, installers may add estimates from other software, but these must not be given more prominence than the standard MCS estimate [13]; compare the standard ones.

In this made-up pair, quote B's kWh per kWp is higher only because it assumes no shade, and its yearly total is higher also because it is bigger (our calculations):

Ask how shade was assessed. MCS says an accurate shade estimate will typically need a site visit, and an estimate made remotely must say performance may be significantly lower or higher if the installed system differs from the estimated values [2].

As a reality check rather than a target: the median Feed-in Tariff solar installation ran at a 9.2 per cent load factor in 2024/25, the lowest on record [6]. That is about 810 kWh per kW over the year (our calculation). Where you live and the roof change this a lot.

Are the savings assumptions believable?

Before you sign, an MCS quote should state the occupancy pattern it assumes for your home (home all day, in half the day or out all day), the annual electricity use it assumes, and how much of the solar electricity your home is expected to use, in kWh and as a percentage [2][13]. If a battery is quoted, it should give that figure both without and with the battery [2]. Check these match your household: MCS says the occupancy pattern should be chosen by asking you [2].

The solar electricity your home does not use is broadly what is exported. If the quote turns kWh into pounds, ask which import and export rates it used, whether you qualify for them, and whether an export limit or the inverter size changes the figures. Installers in the RECC code must base any savings estimate on your actual energy use and set out assumptions such as future energy prices [8], and installers under MCS's redeveloped scheme should tell you not to sign on the strength of specific tariffs [3].

For a battery, ask what it adds beyond solar alone, and for its round-trip efficiency and the energy lost if it charges from the grid [2]. A kWh used at home cannot also be sold to the grid, and MCS says its self-consumption figure is an estimate, not a prediction for your home [2].

How do you check the battery line?

• Nominal and usable kWh. The usable figure is what you can draw on. MCS's estimate uses usable capacity [2]; the government's battery prices are per kWh of nominal capacity [5]. Ask for both.
• Price per kWh. Divide the battery price by its nominal kWh. In the example, £7,200 for 10 kWh is £720 per kWh nominal: that is the figure to compare with the government medians in the table below, which are per nominal kWh. Per usable kWh it is £800 (our calculations). More in solar battery cost.
• Power in kW (its maximum power output) and storage capacity, which MCS's redeveloped scheme says the contract should state [2][3].
• Warranty terms: years, and the capacity or energy throughput guaranteed; makers word these differently. Whether you need a battery and what size is in what size solar battery do I need.

Which terms should you check before signing?

• VAT: installed panels and batteries in homes are zero rated to 31 March 2027, then 5 per cent; equipment supplied without installation is charged at the standard rate [7]. More in VAT on solar panels.
• Deposit: under the RECC code, a deposit should not exceed 25 per cent and deposits must be insured [8]. Under the HIES code, deposit insurance covers deposits up to 25 per cent of the contract or £5,000, whichever is lower, so anything above that is not covered [9]. Under MCS's redeveloped scheme, code membership is no longer mandatory [10], but installers commit to a deposit that is reasonable, justified and part of an agreed payment schedule, and to telling you how it is protected [3].
• Cancellation: for a contract signed at home, you can usually cancel within 14 days, counted from when the goods are delivered for a contract to supply and install [11]. The contract should explain your rights [1].
• Changes after the survey: under the redeveloped scheme, if the design, price or estimate changes significantly, you can continue or cancel without cost and get any deposit back [3].
• Tariffs: the redeveloped scheme says installers should tell you not to sign on the strength of specific energy prices, because tariffs change [3].
• Roof warranty: if the work may invalidate it, the installer needs your written agreement first [3][13].

When should you walk away from a quote?

When you are pressed to sign on the day. Installers under the redeveloped scheme commit not to pressure you [3], and MCS's guidance tells installers to allow plenty of time to review [1]. Be wary too of a quote with no MCS estimate or datasheets before the contract [2][13], a single total with no breakdown [1], or a deposit above 25 per cent from an installer in the RECC code [8]. Another quote to compare is the next step: get a second quote. To check the firm itself, see how to check a solar installer.

Checklist and questions to send back

Anything your quote leaves out is a question to send back in writing.

1. The installer: Business name, contact details and MCS certification number; company registration number if the business is a registered company; VAT number if it is VAT-registered
2. Panels: Make, model, number and watts each, and the total kWp
3. Inverter: Make, model and kW
4. Battery: Make, model, nominal and usable kWh, power in kW, warranty years and terms, backup hardware if you want backup
5. Price: Breakdown of labour, materials and equipment; solar and battery priced separately; extras such as scaffolding listed
6. VAT: Price before VAT, the VAT (zero rate on installed systems to 31 March 2027) and the total
7. Estimate: MCS performance estimate: kWp, kWh per kWp from the MCS table, shade factor, yearly kWh; datasheets; a layout drawing
8. Shade: Was it assessed on a site visit, and how?
9. Deposit: Amount, how it is protected and the payment stages
10. Cancellation: Your cancellation rights in writing
11. Grid: Who applies to the network operator, and whether an export limit applies
12. Roof: If your roof is under warranty, written agreement before work that may invalidate it
13. Guarantees: Workmanship and product guarantees, and any financial protection, with how long each lasts
14. Timing: Start date, how long the job takes, how long the quote is valid
15. Savings: Assumed occupancy pattern and annual electricity use; expected self-consumption in kWh and per cent, without and with any battery; any import and export rates used to give pounds
16. Battery benefit: What it adds beyond solar alone; round-trip efficiency and energy lost if charged from the grid
17. Tariffs: Whether you and the equipment qualify for the rates used

Download the checklist (text file)