Five Questions Your
Installer Hopes
You Never Ask
Intelligent Buyers exist because the solar market needed a consumer champion — not a comparison site. An independent voice with no commercial interest in which company you choose, and every interest in making sure you choose well. This guide outlines the five questions the data says you should ask any installer.
Before you start
We publish this guide because the solar industry holds all the information a buyer needs and has very little incentive to hand it over unprompted. In 2025 alone, 178,947 UK homes went solar — 490 installations every day, one every three minutes. MCS-certified solar now covers 856,026 homes. Prices have fallen 21 percent since the 2023 peak. The technology works, the economics are sound, and the market is competitive. The part that has not kept pace is the quality of information available to the person actually paying for it.
The dominant comparison model in solar involves a consumer completing a single online form and receiving calls from three or four installers within the hour. None of them are quoting against the same specification. None of them are incentivised to tell you that a competitor could do it cheaper, or better, or that your roof is not quite right for the system they are proposing. The process has been built around the seller's interests. This guide exists to put some of that balance back.
The five questions that follow are the ones most likely to make a well-prepared installer comfortable and an under-prepared one evasive. None of them are trick questions. They are the basic due diligence every solar buyer should apply before signing anything — and the ones the industry has quietly relied on most people never asking.
A Note on MCS
MCS (Microgeneration Certification Scheme) is the UK quality mark for small-scale renewable energy. Any installer quoting for solar panels, battery storage, or heat pumps must hold a current MCS certificate for that specific technology. You can verify any certificate number at mcscertified.com. MCS certification is the entry requirement for this industry. It is not, on its own, a guarantee of quality, competitive pricing, or honest advice.
Question 1
Can you show me your MCS installation history for my technology?
Volume and recency reveal what a sales pitch cannot.
Every MCS-certified installer accumulates a record of the installations they complete. Each job is registered, timestamped, and tied to their certificate. This history is not something they advertise, but it is something you can ask for.
The reason it matters is simple: MCS certification covers four distinct technology categories. An installer certified for Solar PV, Battery Storage, Air Source Heat Pumps, and EV charging is not equally experienced across all four. They may have installed two hundred solar systems and three heat pumps. Or they may have a brand-new battery storage certification with no track record behind it.
The Intelligent Buyers Solar Intelligence Report 2026 found that battery storage installations nearly doubled in a single year, up 97 percent in 2025. That growth attracted a significant number of installers adding battery certification to their existing solar credentials. Some of those installers are genuinely experienced. Others are not. You cannot tell from the certificate alone.
What to Ask
Ask for the number of MCS-certified installations completed in your specific technology in the last 12 months, and a list of three recent local installations you can inspect or contact. An installer with genuine volume and local track record should answer this without hesitation. Vagueness here is informative.
The industry does not make this information hard to hide, because most consumers never ask for it. The MCS framework is designed around quality at the point of installation. What happens before, in the sales conversation, is largely unregulated. This question reintroduces some accountability at the stage where it is needed most.
For context: the MCS database lists over 15,000 active installation teams in 2025. The market is large enough that an installer with a thin track record in your technology has no shortage of competitors with more. You have genuine choice. Use it.
The Data Behind This
MCS-certified installations: 856,026 total UK solar homes. Battery storage installations in 2025: 39,400 — a 97% year-on-year increase. The battery market is new enough that experience gaps between installers are wide and meaningful. Source: MCS Certified Data, March 2026.
Question 2
What is the cost per kilowatt, and how does that compare to current market data?
A single headline figure tells you almost nothing. A per-kilowatt breakdown tells you whether you are being charged fairly.
Solar quotes are typically presented as a total installed cost. This is a reasonable way to communicate a price, but it is also a useful way to obscure how a quote compares to the market. A quote for a 6 kW system at £12,000 sounds like a lot. A quote for a 4 kW system at £7,200 sounds like a bargain. Neither statement tells you whether the price is reasonable without a per-kilowatt reference point.
£1,664
per kW today
Market average (Feb 2026)
£2,234
per kW peak
January 2023 peak
21%
price fall
From peak to today
£8,191
avg system
4.5 kW installed
The reason most installers do not quote in cost-per-kilowatt terms is that doing so makes comparison immediate. You would be able to place their number directly against the market average. The way quotes are currently presented — system name, panel brand, battery model, total price — requires more effort to compare, and most consumers do not make that effort.
What to Ask
Divide any quote total by the system size in kilowatts. The current market average is £1,664 per kW. Quotes significantly above this figure deserve a clear explanation. "Premium components" is an acceptable answer if accompanied by specific evidence. "That is just the cost of a quality installation" is not.
Price is not the only variable. A cheaper installer who damages a roof, uses substandard components, or leaves the installation uncertified creates costs that dwarf the initial saving. But a higher price is not, by itself, evidence of quality. It is evidence of a higher price. The burden of proof sits with the installer, not the consumer.
The Data Behind This
Average cost per kW (February 2026): £1,664. Average system cost for 4.5 kW system: £8,191. Peak cost in January 2023: £10,401 (£2,234 per kW). Prices have now fallen 21% from peak and the data signals stabilisation, not further significant decline. Source: MCS Certified Data, March 2026.
Question 3
What is your actual payback period based on my specific usage data?
Generic payback estimates are marketing. A calculation built on your actual consumption is evidence.
The payback period for a solar installation — the point at which the system has generated enough savings to cover its own cost — is one of the most cited figures in solar sales. It is also one of the most variable, least standardised, and most frequently optimistic figures in the industry.
A payback calculation that is genuinely useful requires several inputs specific to your household: your annual electricity consumption in kilowatt hours, your current unit rate and standing charge, the time-of-use pattern of your consumption (whether you are home during the day or not), the orientation and angle of your roof, any shading from trees or neighbouring buildings, and whether you are including battery storage in the calculation.
Most sales-stage payback estimates use none of these. They use national averages for consumption, assume favourable roof orientation, and apply optimistic export rates. The figure they produce is technically defensible and practically useless.
Grid Import Rate
25–30p
per unit bought from grid
SEG Export Rate
4–7p
per unit exported to grid
The financial case for battery storage is a direct consequence of this spread. Selling cheap and buying back expensive is the problem it solves.
What to Ask
Ask the installer to show you the calculation in full, line by line. It should include your actual quoted consumption figure (not a national average), your current energy tariff, the assumed generation output for your specific roof, the Smart Export Guarantee rate they are using, and whether the battery has been factored in separately. If they cannot provide this, the estimate is not built on your data.
This is not a reason to dismiss any estimate that lacks battery modelling. It is a reason to ask for a comparison: what does the payback look like with and without battery storage, using your consumption pattern? An installer with real competence in battery systems should be able to answer this with numbers, not just a general endorsement of the technology.
The Data Behind This
Battery storage installations in 2025: 39,400 — up 97% in a single year. Average grid import rate: 25–30p per unit. Typical SEG export rate: 4–7p per unit. The financial case for battery storage is not theoretical; it is a direct consequence of the spread between import and export pricing. Source: MCS Certified Data and IB Solar Intelligence Report, March 2026.
Question 4
Does my property actually qualify, and what does the survey confirm?
Many properties that look unsuitable are not. Many that look ideal have complications. Only a site survey tells you which category yours falls into.
There is a persistent mental image of the ideal solar property: a large detached house with an expansive, unobstructed, south-facing roof. That image has shaped how many homeowners assess their own suitability before they ever speak to anyone. The data tells a different story.
37%
Detached
30%
Semi-detached
20%
Terraced
13%
Flats & other
Share of 856,026 MCS-certified UK solar homes by property type
Of the 856,026 MCS-certified solar homes in the UK, 37 percent are detached — but 30 percent are semi-detached and 20 percent are terraced. Over 109,000 are flats or apartments. The property type that most people assume rules them out of solar accounts for the majority of UK installations.
The reasons that properties get disqualified at survey stage are usually more specific: severe shading from adjacent buildings or mature trees, structural issues with the roof, planning restrictions in conservation areas, or insufficient roof space. None of these can be reliably assessed from a postcode or a photograph.
What to Ask
Ask whether the quote is conditional on or inclusive of a site survey. If you have received a price without a surveyor visiting the property, ask what assumptions have been made about roof condition, orientation, shading, and available roof space. Any assumption that affects system size affects both the generation estimate and the payback calculation.
The IB Solar Intelligence Report 2026 notes that regional solar adoption has as much to do with community momentum as with sunshine hours. The Isle of Anglesey — one of the cloudiest parts of the UK — has the highest solar penetration of any local authority at 14.1 percent of households. Ceredigion follows at 12.5 percent. This is not about irradiance. It is about word-of-mouth, installer competition, and the visible presence of panels on neighbouring properties.
The Data Behind This
Semi-detached installations: 255,556. Terraced installations: approximately 171,000. Flat and apartment installations: approximately 109,000. Together these account for 63% of all MCS-certified UK solar installations. The detached-house assumption excludes the majority of the market. Source: MCS Certified Data, March 2026.
Question 5
Who are you actually quoting against, and are those quotes built on the same specification?
Getting three quotes is standard advice. Getting three comparable quotes is the part the industry prefers you not to think about.
The standard advice given to solar buyers is to get at least three quotes. This is good advice, as far as it goes. What it does not address is the mechanism by which most consumers currently find those quotes. The dominant comparison model in the UK solar market involves a consumer completing a single online form. That form is sold as lead data to three or four installers simultaneously. All of them call within the hour.
This process produces multiple quotes. It does not produce comparable quotes. Each installer is quoting the system they prefer to sell: different panel brands, different inverter manufacturers, different battery specifications, different assumed system sizes. The difference in output, warranty terms, component longevity, and price makes comparison difficult by design.
The Problem
The industry is structured this way not because it serves the consumer but because it serves the installer. A consumer who is comparing incompatible specifications is a consumer who cannot confidently walk away from a higher price. Confusion is commercially useful.
The Solution
Establish a reference specification before you invite quotes: a system size in kilowatts, a panel brand tier, an inverter brand, and a battery specification if relevant. Every quote should map to the same spec — or explain specifically why it deviates from it.
With approximately 15,000 installation teams active in 2025, genuine competition exists at the local level. This is a buyer's market in terms of volume. It does not automatically become a buyer's market in terms of information. That requires the consumer to insist on the terms of comparison, not to accept the terms offered.
What to Ask
Before you accept any quote, establish a reference specification: a system size in kilowatts, a panel brand tier, an inverter brand, and a battery specification if relevant. Ask each installer to quote against that specification, or to explain specifically why they are deviating from it. A quote that cannot be mapped to a consistent specification cannot be meaningfully compared.
A like-for-like quote request is not an unusual or unreasonable demand. It is the minimum standard for any significant financial decision. A kitchen installation, a conservatory, a driveway: in each case, you would expect quotes to cover the same materials, the same dimensions, the same scope of work. Solar is no different. It is a large purchase. Treat it accordingly.
The Data Behind This
Active installation teams in 2025: approximately 15,000. Annual installations: 178,947. Average system cost: £8,191. At that price point, a 10% variance between comparable quotes represents over £800. The market has genuine competition. You are under no obligation to accept the first quote, the lowest quote, or the most confidently delivered quote. Source: MCS Certified Data, March 2026.
What these questions are for
None of the five questions above are designed to catch installers out. Most solar companies are competent, honest businesses operating in a market that does not always reward the transparent ones. These questions are designed to separate those companies from the ones that are not.
An installer who answers all five fluently and with specific evidence — installation history, per-kilowatt pricing, a personalised payback calculation, a post-survey quote, a like-for-like specification — is an installer worth engaging with seriously. An installer who deflects, generalises, or becomes defensive when asked straightforward questions about their own pricing and track record is an installer who has given you the answer you needed, without your having to wait for it to emerge in the contract.
Solar is, by any reasonable analysis, one of the better home investments available to a UK homeowner in 2026. The market is mature, the technology is proven, the economics are favourable, and the price has already corrected from its peak. The information gap is the remaining barrier. These questions close it.
About Intelligent Buyers
Know more. Pay less. Choose better.
Intelligent Buyers is a consumer champion for UK homeowners considering solar. We provide a free, independent solar plan, match homeowners to three vetted, MCS-certified companies, and issue a £250 voucher redeemable with whichever installer you choose.
We are not an installer. We do not sell solar panels. We do not auction your contact details to the highest bidder. Every company in our network pays the same fixed fee.
Intelligent Buyers · Consumer Champion for Solar Buyers · intelligentbuyers.co.uk · A trading name of Green Funnel Ltd
Data references: MCS Certified Data, March 2026. IB Solar Intelligence Report, March 2026.