How to Vet a London Solar Installer — 9 Red Flags + Green Flags

MCS (Microgeneration Certification Scheme) registration is the single most important credential. Without MCS, your installer cannot certify the install for SEG export payments, cannot offer 0% VAT (active until 1 May 2027), and cannot register for any grant.

Verify on mcscertified.com — type the company name. The cert shows current status, accreditation bodies, and product scope (PV, battery, ASHP).

An installer claiming 'we're MCS' but not appearing on the public register is either lying or recently lapsed. Lapsed status is common when installers skip annual fees. Either way, walk.

RECC (Renewable Energy Consumer Code) is the consumer protection framework backed by Trading Standards. Membership means binding arbitration in case of dispute and a code of conduct around door-to-door sales.

Combined MCS + RECC is the standard for any reputable UK solar installer. Verify on recc.org.uk.

RECC handles the most common dispute — installer overpromises generation, customer feels under-served. Without RECC, the only recourse is court.

A proper solar quote includes: roof aspect and pitch, panel layout PDF, predicted annual generation (kWh) from MCS-mandated calculation, shading factor analysis, and string design.

If a 'quote' arrives as a single price with no design, it's not a quote — it's a sales hook. Insist on a written design before paying any deposit.

Reputable London installers use solar design software (Easy-PV, OpenSolar) that produces a 4-6 page PDF. If you don't see this, you haven't been quoted.

Door-to-door solar sales in London 2026 is overwhelmingly cowboy territory. The pattern: 'we're doing your street', 'limited grant', 'sign today for £2,000 off'.

RECC forbids high-pressure tactics. Any installer using them is either non-RECC or actively breaching their code.

Tell door-knockers you don't buy from doorstep sales and you'll seek 3 written quotes via referral. The honest ones leave a leaflet; the cowboys argue.

Roof condition, accessible scaffold points, internal cable run distance, and consumer unit space all affect cost. An installer quoting without seeing these is winging it — and the post-survey 'extras' bill will surprise you.

Always demand a physical site survey before signing. Reputable London installers offer free surveys; the quote follows 3-5 days later.

If the company runs a fully-online quote model with no site visit, expect at least one 'site complexity' surcharge after deposit.

'Premium panels' and 'top-tier inverter' are red flags. A real quote names the panel model (JA Solar JAM72S30-545, Trina Vertex TSM-505NEG18R.28, Aiko Neostar 460), the inverter (Solis S6-EH3P5K, GivEnergy AIO, SolarEdge SE5000H), and the battery if any.

Without product names, you can't price-compare, can't check warranty, and can't verify MCS product certification.

If you ask for the equipment list and get pushback, it's because comparable products are cheaper elsewhere.

Industry standard in 2026 is 10% deposit on signing, 80% on material delivery, 10% on commissioning. RECC limits deposit to 25% maximum.

Anyone asking for 50%+ before scaffold goes up is either cashflow-stressed (high failure risk) or operating a deposit-and-vanish scam.

Pay by credit card where possible for Section 75 protection — deposits between £100 and £30,000 are covered for non-delivery.

An insurance-backed guarantee (IBG) means the workmanship warranty is honoured even if the installer goes bust. Without IBG, a 10-year workmanship promise from a 2-year-old company is just paper.

GuaranteeProtection Insurance (GPI) and HIES are the common UK schemes. RECC requires its members to offer an IBG on installs.

Verify the IBG before the install. Should be issued within 14 days of commissioning. If it doesn't arrive, chase it via RECC.

Ask for 3 references in your borough completed in the last 12 months. A reputable installer provides these in writing within 24 hours.

Ask about DNO (Distributor Network Operator) registration — UK Power Networks for London. The install must be notified to DNO before commissioning (G98 for under 3.68 kW per phase, G99 for above).

A clean G98/G99 notification means the install is legal for grid export. Without it, your SEG payments may be withheld or your inverter may need re-commissioning.

The combination of all 9 checks filters 95% of cowboy installers. The remaining 5% might still be average; that's why references matter most.