| MCS standard | MIS 3002 issue 6.0, dated 18 March 2026 |
|---|---|
| MCS certificate | Generated within 10 working days of commissioning |
| Consumer Code | Version 9, published 1 July 2026 |
The quote is a contract in waiting
A written quote is the best evidence you will have of what you were promised. If it is vague, any dispute later becomes your word against the installer’s. A clear one protects both sides.
Two documents set the bar in the UK. The first is the MCS standard, MIS 3002. It covers the technical facts you must get. The second is the Renewable Energy Consumer Code. It covers how an installer quotes, signs and sells. Not every installer belongs to both, but you can still use them as a yardstick because they reflect good practice.
Use the sections below as a checklist. Then run the figures through our free quote checker and follow the like-for-like comparison method.
Equipment
The quote should name each major part. It should not just describe it. Look for these.
- Panel make, model, wattage and quantity
- Inverter make and model, plus any optimisers or microinverters
- Battery make, model and usable capacity in kWh, if included
- Mounting system, meter and monitoring equipment
Under the MCS standard, the installer must send the maker datasheets for the panels and the inverter. A battery or optimiser needs its own datasheet too. A drawing of the proposed panel layout must come with them, because layout drives output.
Product choice affects cost and performance, so it is worth reading about string inverters, microinverters and optimisers. Equally, the quote should show the product warranties, because those terms differ by maker.
The performance estimate
MCS requires a written estimate of annual generation and self-consumption before you sign. It follows a set table. That table shows the size in kWp, the roof direction and tilt, the postcode region and the shade factor. It ends with the yearly output in kWh.
It also states the occupancy pattern and electricity use assumed for the self-consumption figure. If a battery is included, the table repeats the estimate with storage.
The estimate must carry a note. The figure is a guide for year one. It is not a promise. Compare it with any savings claim in the sales pitch, because a bigger number needs a clear reason.
Pricing
The Consumer Code lists what a quote must show. It should list the goods and the services. It should price them apart. It must also include safety checks and all taxes, including VAT.
It should also say how long the quote is valid, how you will pay and when. Finally, it should give a timetable and completion dates. A quote that gives only one total therefore fails this test.
While you read, look for the “no surprises” principle. When the final invoice arrives, there should be no unexpected items compared with the quotation, unless you agreed them beforehand. If anything changes, the installer must tell you before the contract is agreed and explain how it affects the completion date.
Installation scope
Next, check what the work covers. The Consumer Code asks for a list of the survey, design and fitting work. It also asks for a list of what is left out, such as permits and repairs to the property.
Check for these items in particular:
- Scaffolding and roof access
- Fixings, waterproofing and cable routes
- Fire and isolation provisions
- Consumer unit or other electrical upgrades
- Testing, commissioning and making good
Scaffolding is the item that most often goes missing, so see our guide to scaffolding costs. Roof type matters too. A quote for a flat roof needs a different mounting plan, which is why solar panels on a flat roof deserve their own check.
The quote must also name site conditions that could add chargeable work, with the hourly or daily rates that would apply. For example, a hidden roof defect could raise the bill, so ask what happens in that case.
Survey and timing
The Code says installers should carry out, and pay for, a technical site survey before you sign, if possible. If they charge for it, the cost must be reasonable and the installer must say when it is refunded. Where the survey comes after you sign, the performance estimate may change, and you then have the right to cancel without penalty.
Timing should appear in the quote, because delays cost you too. Read how long installation takes so you can judge whether the dates are realistic.
Admin and handover
The paperwork is easy to ignore until you need it. However, a good quote says who handles each step.
- Planning and building rules. The installer must tell you what approvals the job may need and who handles them.
- Grid notice. The MCS contractor must tell your network operator, using the G98 or G99 process.
- Certification. The installer logs the system on the MCS database within 10 working days of commissioning. This creates your MCS certificate.
- Handover pack. It must include commissioning records, maintenance advice, manuals and warranty details.
At handover, the MCS contractor also signs a declaration that the install meets the standard. It lists the key components and the performance estimate, and it recommends when to schedule the first inspection. Our guide to warranties and certificates explains how to use these papers.
Questions to ask before you sign
Some gaps are best closed in writing, because verbal answers are hard to prove. Our list of questions to send every installer covers the calculation, certification, delivery and aftercare.
Since prices differ by area, also read local pages such as solar quotes in London and what to expect in the West Midlands. For a national view, see typical solar panel costs.
If you want quotes from MCS-certified installers to compare, you can request them here. Solar Panel Price Check is independent and is not an installer.