How to Choose a Solar Installer: Red Flags and Green Flags

Your installer matters as much as your panels. A great system poorly installed underperforms, leaks, or fails prematurely. A good system well installed runs trouble-free for decades. Here's how to tell the difference before you sign.

Green Flags (What Good Installers Do)

MCS Certified

This is the minimum requirement. MCS (Microgeneration Certification Scheme) certification means the installer meets quality standards, carries appropriate insurance, and follows approved installation practices. Without MCS, you can't register for SEG payments and have limited industry recourse.

Verify at: mcscertified.com/find-an-installer

Detailed Written Quote

A good quote includes:

• Exact panel make, model, and number
• Exact inverter make and model
• Battery specification (if included)
• Total installed price including VAT
• Payment terms and schedule
• Estimated annual generation for YOUR roof (not generic figures)
• Warranty terms for panels, inverter, and workmanship
• Timeline for installation

If a quote is vague ("solar panel system, 10 panels, £X,XXX"), ask for specifics.

Site Survey Before Quoting

Reputable installers survey your property before quoting — checking roof condition, orientation, shading, electrical capacity, and access. A quote without a survey is guesswork.

Some installers do a preliminary remote assessment (using Google Earth/satellite imagery) followed by an in-person survey before finalising the quote. This is fine and increasingly common.

Workmanship Warranty

Beyond manufacturer warranties on equipment, the installer should provide a workmanship warranty covering the installation itself — typically 5–10 years. This covers roof penetrations, wiring, mounting, and other installation-specific work.

Clear Communication

Good installers explain what they're recommending and why, answer your questions without jargon, and don't dismiss your concerns. They're willing to discuss alternative configurations and explain trade-offs.

Insurance

Ask for proof of:

• Public liability insurance (minimum £2 million, preferably £5 million)
• Professional indemnity insurance
• Employer's liability insurance (if they have employees)

Red Flags (What Bad Installers Do)

High-Pressure Sales

"This price is only available today." "We have one slot left this week." "If you don't sign now, the price goes up." These are pressure tactics, not genuine scarcity. Walk away.

No MCS Certification

An installer who claims MCS isn't needed, or who offers to do the work without MCS "to save you money," is either cutting corners or isn't qualified. This also means no SEG eligibility.

Massive Deposit

Asking for more than 25% upfront before work starts is unusual. Demanding full payment before installation is a major red flag. Standard terms: 10–25% deposit, balance on completion.

No Written Quote or Contract

If the installer is reluctant to put specifics in writing, something is wrong. Every detail should be documented before you sign.

Vague About Equipment

"We'll install premium panels" without specifying make and model means they'll install whatever is cheapest on the day. Insist on exact specifications.

No Site Survey

A quote based solely on a phone conversation or Google Earth view, with no in-person survey, risks incorrect sizing, missed shading issues, or unexpected costs on installation day.

Cash-Only or Bank Transfer Only

Legitimate businesses accept credit card payments. Cash-only or bank-transfer-only payments remove your Section 75 consumer protection.

Claiming Unrealistic Savings

"Your system will pay for itself in 3 years" or "You'll never pay an electricity bill again" are almost certainly exaggerations. Be wary of anyone promising returns that seem too good.

Questions to Ask Every Installer

1. "Are you MCS certified? Can I verify your certification number?"
2. "What specific panels and inverter are you quoting?"
3. "What generation do you estimate for my specific roof?"
4. "How does that estimate account for shading?"
5. "What warranty do you provide on the installation workmanship?"
6. "What are your payment terms?"
7. "How long have you been trading?"
8. "Can you provide references from recent local installations?"
9. "What happens if there's a problem after installation — what's your support process?"
10. "Will you handle the DNO notification and MCS registration?"

Comparing Quotes

When you have 3+ quotes, compare:

Specification

Are they quoting the same panels and inverter? Different equipment at different prices is a specification difference, not a price difference. Compare like-for-like.

Total Installed Price

Including VAT (0% for residential solar in the UK). No hidden extras for scaffolding, electrical work, or DNO notification.

Estimated Generation

Each installer should estimate annual generation. Significant differences for the same system on the same roof suggest one quote has more realistic assumptions.

Warranty Coverage

• Panel product warranty: 12–30 years (varies by manufacturer)
• Panel performance warranty: 25 years (standard)
• Inverter warranty: 5–12 years (varies)
• Workmanship warranty: 5–10 years (varies by installer)

What's Included

Check whether the quote includes:

• Scaffolding
• DNO notification
• MCS certification
• Monitoring setup
• Building regulations sign-off
• Post-installation support

Where to Find Good Installers

MCS Database

mcscertified.com/find-an-installer — search by postcode for certified installers near you.

Which? Trusted Traders

which.co.uk/trustedtraders — vetted and reviewed by Which? members.

Local Recommendations

Ask neighbours with solar, local community groups, or Nextdoor for installer recommendations. Personal experience is often the most reliable indicator.

Solar Comparison Platforms

Sites that connect you with multiple installers can be useful for getting quotes quickly, but verify each installer's credentials independently.

The Decision Framework

1. Eliminate anyone without MCS certification
2. Eliminate anyone with significant red flags (pressure tactics, no written quote, cash-only)
3. Compare remaining quotes on specification, price, warranty, and aftercare
4. Check reviews and references for your shortlisted installers
5. Choose the installer you trust — not necessarily the cheapest, but the one who communicates clearly, quotes accurately, and backs their work

A good installer at a fair price will serve you better over 25 years than a cheap installer who cuts corners. Solar is a long-term investment — choose a partner who'll be around for the long term.

For more on getting and comparing quotes, see our quotes guide. If you encounter problems, our reporting scams guide explains your options.

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