What Your Solar Quote Must Contain
Three quotes for the same roof can describe three different jobs. The lines every written solar quote should carry, and the exclusions that explain the price gap.
What Your Solar Quote Must Contain
Three quotes for the same roof can differ by thousands of pounds and still be describing three different jobs. The way to tell them apart is not the headline price. It is whether each document names the same equipment, the same assumptions, and the same person responsible for the paperwork.
The Energy Saving Trust is blunt about how many you should gather.
Get quotes from at least three installers. Make sure the installers you look at are MCS-certified, which ensures they adhere to a strict code of conduct.
Here is what each of those documents should contain, and what it means when something is missing.
1. The legal entity, not just the trading name
A quote should name the company that will hold the contract, with its registered number. This matters more than it sounds, because MCS certification is held by a legal entity and a firm's trading name is not always the name on the register.
Ask which registered company holds the certification, for which technology, and then check that name yourself. Certification is granted per technology, so a contractor certified for solar PV is not automatically certified for battery storage. There is a longer walkthrough of that check on our page about verifying an MCS-certified installer.
2. The equipment, by make and model
"Premium panels" is not a specification. The quote should state:
- Module make, model and wattage, and how many
- Total array size in kWp
- Inverter or battery inverter make and model
- Battery make, model and usable capacity in kWh, if included
- Mounting system make and model
Mounting matters more than most homeowners realise, because it is the part that penetrates your roof covering. If the mounting system is not certified under the MCS product standard, the contractor should be supplying structural and wind loading calculations instead, along with evidence that the roof's fire performance and weather-tightness are maintained.
3. The generation estimate, with its assumptions
Any quote can print a kWh figure. A useful quote prints the assumptions underneath it: which roof slopes, what orientation, what pitch, what shading was allowed for, and what system losses were assumed.
Ask whether the estimate was produced to the current version of the MCS solar PV standard. MIS 3002 moved to version 6.0 on 18 March 2026 and compliance became mandatory on 18 June 2026, so a contractor working to an older version is working to a superseded document.
Be suspicious of any estimate that comes in suspiciously high for an east or west roof, and of any that quotes a single annual number with no seasonal breakdown. The winter figure is what determines whether a battery will cycle usefully for much of the year.
4. The price, the VAT position and the exclusions
The total should be stated inclusive of VAT, and right now that VAT should be zero. HMRC zero-rates the installation of qualifying energy-saving materials in residential accommodation until 31 March 2027, after which the rate reverts to 5%.
What separates a complete quote from an optimistic one is usually the exclusions list. Check explicitly whether these are in or out:
| What to check | Why it matters |
| Scaffolding | Often a separate line, and over-runs can be chargeable |
| Network operator application fee | G99 applications can carry a charge |
| Consumer unit upgrade | Common on older properties and rarely cheap |
| Roof repairs or tile replacement | Discovered at strip-back, not at survey |
| Bird or squirrel proofing | Frequently an upsell later |
| Scaffold alarm or licence for pavement use | Needed where scaffold sits on a public footway |
| MCS certification and registration | Should be included, not extra |
5. Who does the grid paperwork
Every grid-connected system has to be registered with your distribution network operator. The quote should say who submits it, who tracks it, and which route applies.
Below 16 A per phase, which is 3.68 kW on a single-phase supply, the route is a G98 notification sent within 28 days after commissioning. Above that, a G99 application needs prior permission before installation starts, which creates a lead time. MCS notes that adding battery storage alongside solar is likely to take the total above 16 A per phase, so a battery usually moves you into G99 territory. If you might add battery storage later, say so now so the application is made once.
Also confirm who registers you for export payments, and remember that the export tariff is shopped separately from the installation. You can model what the export side is worth with our SEG calculator.
6. The warranties, and who honours them
There are usually at least three separate warranties in a solar installation: the module product warranty, the inverter or battery warranty, and the installer's own workmanship warranty. They are honoured by different parties and they are not the same length.
Ask for all three in writing, with the honouring party named against each. A headline warranty figure in a brochure is marketing. The document that matters is the one that says who you call and what they are obliged to do.
Red flags worth walking away from
- No kWh generation estimate, or an estimate with no stated assumptions
- No module or inverter make and model
- No named legal entity or company number
- A discount that expires if you do not sign today
- A refusal to put the exclusions list in writing
- A verbal assurance about certification with no register entry you can check
What to do next
Get three quotes, lay them side by side, and compare the specification and the exclusions before the price. If one is substantially cheaper, find the line that explains why. Nine times out of ten it is in the exclusions or the mounting system.
When you are ready to be surveyed, our residential solar installation page sets out the full process, the permitted development limits, and what a Hertfordshire roof generates at each orientation.
