Why Your Choice of Installer Matters More Than Your Choice of Panels
Here’s something most solar panel guides won’t tell you: the quality of your installation matters far more than the brand of panels on your roof. A good installer fitting mid-range panels will outperform a bad installer fitting premium ones. Poor installations lead to reduced output, roof leaks, electrical faults and systems that underperform their projections for decades.
We’ve seen quotes for identical systems vary by 40% or more. The cheapest isn’t always the worst and the most expensive isn’t always the best — but you need to know what to look for. This guide covers exactly that.
Step 1: Start With MCS Certification (Non-Negotiable)
The Microgeneration Certification Scheme (MCS) is the government-backed quality standard for renewable energy installations in the UK. Do not use an installer who isn’t MCS-certified. This isn’t optional — it’s the baseline.
Without MCS certification:
You can’t claim the 0% VAT rate on your installation. You can’t register for the Smart Export Guarantee (SEG) to get paid for surplus electricity. You won’t qualify for any government grants. Your home insurance may not cover the installation. You have no access to the MCS dispute resolution process if things go wrong.
Check an installer’s certification at mcscertified.com using their “Find an Installer” tool. Don’t take their word for it — verify it yourself. MCS has issued warnings about companies falsely claiming certification.
Step 2: Get at Least Three Quotes
This is the single most important piece of advice in this guide. Get a minimum of three quotes from different MCS-certified installers, and compare them carefully.
Each quote should include: the number and brand of panels, the inverter brand and type (string or micro), total system size in kWp, estimated annual generation in kWh, all costs including scaffolding, DNO notification and VAT, the warranty terms (panels, inverter and workmanship separately), and the estimated installation timeline.
If a quote is missing any of these, ask for them. If the installer can’t or won’t provide them, move on.
Step 3: Check Their Track Record
Reviews
Check Google Reviews, Trustpilot and the MCS installer page for recent reviews. Look for patterns rather than individual complaints — every company gets the odd bad review. What matters is how they respond to problems and whether the same issues come up repeatedly.
Experience with your type of property
Ask the installer how many installations they’ve done on properties similar to yours. A company that specialises in new-build estates may not be the best choice for a Victorian terrace with a complex roof. Ask for photos or case studies of similar projects.
How long they’ve been trading
Solar installation companies come and go. A company that’s been trading for 5+ years is more likely to be around to honour their warranty in 10 years’ time. Check Companies House for their registration date and financial health if you want to be thorough.
Step 4: Understand What You’re Being Quoted For
Panels
Most UK installers use panels from a handful of reliable manufacturers: Longi, JA Solar, Trina, Canadian Solar, and at the premium end, SunPower and REC. All of these are solid choices. The difference between a “budget” and “premium” panel from any of these manufacturers is typically 1–3% efficiency — meaningful over 25 years but not worth paying double for.
Inverters
The inverter converts DC electricity from your panels to AC for your home. This is arguably more important than the panels themselves, because inverters fail more often and have shorter warranties. Good brands include SolarEdge, Enphase (microinverters), GivEnergy (hybrid), Solis and Fox ESS. If the quote lists an inverter brand you’ve never heard of, research it carefully.
Mounting and fixings
Ask what mounting system they use and whether it’s suitable for your roof type. Slate roofs, flat roofs and listed buildings all require different approaches. Poor mounting is one of the most common causes of post-installation problems, including roof leaks.
What’s NOT included
Check whether scaffolding is included (it adds £300–£800 to the cost). Check whether the DNO notification fee is included. Check whether the MCS certificate is included. Some installers quote low but add these as extras.
Step 5: Assess the Site Survey
Any reputable installer will conduct a site survey before giving you a final quote. This should be a physical visit to your property, not a remote desktop assessment from Google Earth (though a good installer may use satellite imagery as a starting point).
During the survey, the installer should check: your roof’s structural condition and orientation, shading from trees, chimneys, neighbouring buildings, your consumer unit (fuse board) and whether it needs upgrading, the best route for cabling from roof to consumer unit, and where the inverter and any battery will be located.
If an installer gives you a firm quote without visiting your property, that’s a red flag. Remote quotes are fine as initial estimates, but the final price should be based on a physical assessment.
Red Flags: When to Walk Away
Based on our research and reports from consumer protection bodies, here are the warning signs that should make you look elsewhere:
Cold calling or door-to-door sales. Reputable solar companies don’t need to knock on doors. Unsolicited approaches are the single biggest predictor of a poor experience. MCS has issued public warnings about fraudulent companies cold-calling homeowners.
Pressure to sign today. “This price is only available if you sign now” is a classic high-pressure tactic. Any genuine offer will still be available tomorrow. You have a legal 14-day cooling-off period for contracts signed at home — any company that tries to rush you past this is one to avoid.
“Free solar panels.” The free solar panel model (where a company installs panels for free and keeps the feed-in tariff payments) died with the Feed-in Tariff in 2019. Anyone still advertising this is either out of date or running a scam. Some schemes exist for low-income households through government grants, but these go through official channels, not door-to-door salespeople.
Unrealistic savings claims. “Your energy bills will drop to zero” or “You’ll earn thousands from the grid” are almost certainly exaggerations. A good installer will give you a realistic estimate based on your roof, location and usage patterns — and it won’t be zero bills.
Large upfront deposits. A deposit of 10–25% is normal. If an installer wants 50%+ upfront before any work has started, that’s a concern. Some payment-on-completion or staged-payment arrangements are available from larger companies.
Subcontracting without disclosure. Some national companies sell the installation and then subcontract it to a local crew you’ve never heard of. Ask directly: “Will your own team do the installation?” If they subcontract, ask who to and check that company’s credentials too.
No written warranty. You should receive separate warranties for: panels (typically 25 years performance guarantee from manufacturer), inverter (5–12 years from manufacturer), and workmanship (minimum 2 years from installer, good ones offer 5–10 years). If the installer can’t provide these in writing before you sign, don’t sign.
After Installation: What to Check
Once the installation is complete, make sure you receive:
MCS certificate — This is your proof of a certified installation. You need it for SEG registration and any future grant applications. If the installer doesn’t provide this, chase it immediately.
DNO notification confirmation — Your installer should notify your local Distribution Network Operator about the installation. Ask for confirmation this has been done.
Electrical certification — An Electrical Installation Certificate (EIC) or Minor Works Certificate confirming the electrical work meets BS 7671 regulations.
System handover documentation — Including the system design, panel layout, inverter settings, monitoring setup instructions and all warranty documents.
Building control sign-off — Solar panels on most homes fall under permitted development, but if your property is listed, in a conservation area, or the panels are mounted on a flat roof visible from a highway, you may need planning permission. Your installer should have confirmed this during the survey.
Where to Find Good Installers
MCS Find an Installer (mcscertified.com): The official search tool. Every installer listed here is verified and certified.
RECC (Renewable Energy Consumer Code): Installers who are RECC members follow an additional consumer protection code. If something goes wrong, RECC offers a dispute resolution service.
Local recommendations: Ask neighbours, friends or family who’ve had solar installed. A personal recommendation from someone whose system is working well after a few years is worth more than any online review.
Solar Together: A group-buying scheme run by local councils that negotiates bulk pricing from vetted installers. Available in selected areas — check your council’s website.
How We Researched This Guide
We reviewed MCS guidance, RECC consumer protection codes, and reports from consumer protection organisations about common solar installation issues. Red flags are based on documented complaints and enforcement actions. This guide was last updated April 2026. Always verify an installer’s current MCS certification status before proceeding.