01
Normalise the system
Record array kWp, panel count and model, inverter model, battery usable kWh, mounting arrangement and monitoring for each quote.
02
Normalise the work
Compare scaffolding, roof work, cabling, consumer-unit work, grid applications, commissioning, bird protection, making good and handover documents.
03
Normalise the forecast
Compare generation, self-consumption, tariff and degradation assumptions. A larger savings figure may simply use more optimistic inputs.
04
Check where the price sits
Prices well below roughly £1,400 per kWp often mean sub-tier equipment or a non-MCS installer; MCS certification is required to register for Smart Export Guarantee payments, and the lost export income over 25 years can outweigh a lower upfront price. Prices well above £2,200 per kWp are not automatically wrong, but ask what specifically justifies the difference.
05
Check the sales process, not just the equipment
Installers who are also members of the Renewable Energy Consumer Code (RECC) commit to defined standards for marketing, quotations, deposits, contracts and after-sales service, with access to independent dispute resolution. RECC membership sits alongside MCS certification — one covers installation quality, the other covers how you were sold to and what happens if something goes wrong.