Worthwatt solar quote checklist (14 October 2026)

[ ] 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
[ ] Panels: Make, model, number and watts each, and the total kWp
[ ] Inverter: Make, model and kW
[ ] Battery: Make, model, nominal and usable kWh, power in kW, warranty years and terms, backup hardware if you want backup
[ ] Price: Breakdown of labour, materials and equipment; solar and battery priced separately; extras such as scaffolding listed
[ ] VAT: Price before VAT, the VAT (zero rate on installed systems to 31 March 2027) and the total
[ ] Estimate: MCS performance estimate: kWp, kWh per kWp from the MCS table, shade factor, yearly kWh; datasheets; a layout drawing
[ ] Shade: Was it assessed on a site visit, and how?
[ ] Deposit: Amount, how it is protected and the payment stages
[ ] Cancellation: Your cancellation rights in writing
[ ] Grid: Who applies to the network operator, and whether an export limit applies
[ ] Roof: If your roof is under warranty, written agreement before work that may invalidate it
[ ] Guarantees: Workmanship and product guarantees, and any financial protection, with how long each lasts
[ ] Timing: Start date, how long the job takes, how long the quote is valid
[ ] 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
[ ] Battery benefit: What it adds beyond solar alone; round-trip efficiency and energy lost if charged from the grid
[ ] Tariffs: Whether you and the equipment qualify for the rates used

Two sums:
1. Solar part of the price divided by total kWp = pounds per kWp. DESNZ mean for MCS installations on existing homes in Great Britain, 2025-26, per kW of total installed capacity (TIC): 1,651 pounds for 4 to 10 kW, 2,109 up to 4 kW. DESNZ leaves out batteries, extended warranties and other material or works: take batteries and extended warranties out first, try extras such as bird mesh with and without, and if labour or scaffolding is not split, try the sum both ways.
2. Estimated yearly kWh divided by total kWp = kWh per kWp. Compare the MCS standard estimates of quotes for the same roof faces.
Battery: battery price divided by nominal kWh, against the DESNZ median for its size band.

Full guide: How to check a solar quote, on the Worthwatt site.