The 14-line checklist
| Line | What good looks like |
|---|---|
| Company name and MCS number | Matches the MCS register, which lists solar PV for that firm. |
| Panel make and model | An exact model number you can look up, not “tier 1 panels”. |
| Inverter make and model | And whether it can take a battery later. |
| System size and layout | kWp, number of panels, which roof faces, a layout drawing. |
| Generation estimate | Annual kWh for your roof, with shading accounted for. |
| Self-use and export assumptions | How much of the output they expect you to use yourself. |
| Scaffolding and access | Included and itemised. |
| Extras | Bird protection, isolators, monitoring, any battery, itemised. |
| VAT | 0% on a home installation they supply and fit (until 31 March 2027). |
| Warranties | Panel product and power, inverter, workmanship, and the insurance behind it. |
| Deposit and payment stages | How the deposit is protected; staged payments. |
| Grid notification | Who notifies the network operator (for most homes within 28 days of commissioning). |
| Paperwork at handover | MCS certificate, electrical certificate, warranties, manuals. |
| Timeline | Survey, install and commissioning dates in writing. |
Comparing quotes fairly
Put the quotes side by side and normalise them: the same system size (or compare price per kWp), the same inclusions (scaffold, monitoring, battery or not), and the same warranties. Then compare the generation estimates: a quote that claims much more output from the same roof needs to show why. Check the panel datasheets with our best solar panels UK guide.
Savings figures should rest on the generation estimate and a realistic self-use share. Export through the Smart Export Guarantee is paid at a rate each supplier sets; the Energy Saving Trust puts it at around 12p a unit typically.
Warning signs
- No named models, or a promise to “confirm equipment later”.
- No survey, or no generation estimate.
- A price that only holds if you sign today.
- VAT at 20% on a domestic installation without explanation.
- Most of the price wanted up front, with no stated protection.
If any line is missing, ask for it in writing before you sign. A firm worth using will add it. Then check the firm itself: how to check an MCS installer.