Seven factors move the price of a UK solar quote: system size, panel tier, inverter type, roof access and scaffold requirements, electrical works, installer overhead, and whether battery storage is included. Together these commonly produce a 20–40% spread between quotes for the same property
Size is the largest single driver, but not proportionally. Cost per kilowatt falls as systems get bigger, because scaffold, survey, DNO paperwork and the crew’s travel are fixed costs spread across more panels.
Moving from 4kW to 6kW might add 35% to the total price while adding 50% to generation capacity. If your roof and consumption support the larger system, it is usually the better value per unit — which is why installers often propose more capacity than homeowners expect.
Less than most people assume. Panels are roughly 30% of the total bill, so moving from budget to premium Tier 1 panels on a 4kW system typically adds £600–£900 to a £7,500 job.
What you get for it: higher efficiency (more output from the same roof area), longer product warranties, and a manufacturer with the financial stability to honour a 25-year performance warranty. That last point matters more than the specification sheet — a warranty is only as good as the company behind it.
Because they are quoting different architectures.
If two quotes differ significantly and one specifies microinverters, that is likely most of the gap — and it may be the right call for your roof. Ask each installer why they chose that architecture for your property. A good installer will have a reason specific to your roof, not a general preference.
This is the most underestimated factor in solar pricing.
Scaffold typically runs £600–£1,200 and is driven by height, roof pitch, the number of elevations needing access, and street access for the scaffold lorry. A two-storey semi with a driveway is straightforward. A three-storey Victorian terrace on a narrow street with no parking is not.
Roof covering matters too. Slate is slower and more fragile to work with than concrete tile. Some older roofs need battens replacing before mounting rails can go on — that should be flagged at survey, not discovered mid-install.
Solar connects into your existing electrical system, and that system sometimes needs bringing up to standard first:
A properly surveyed quote prices these. A remote-estimate quote often does not, which is where “if required” clauses come from.
Larger installers carry more overhead — call centres, marketing spend, sales commission — and it is in the price. Smaller local installers usually have lower overhead but less capacity, and may be booked months ahead in peak season.
Travel distance also counts. An installer 60 miles away is pricing two days of crew travel into your job.
Neither model is inherently better value. A national installer may offer stronger warranty backing; a local one may give you better aftercare and answer the phone in year four. What matters is that you compare like with like — and that both hold current MCS certification.
How to Compare Solar Quotes UK?
£3,000–£6,500, depending on capacity and brand. It is the largest optional line on a solar quote.
Two things worth knowing before you decide. First, fitting the battery alongside the panels is cheaper than retrofitting — you avoid a second scaffold and a second electrical visit. Second, a battery raises self-consumption but also raises the capital outlay, so it can lengthen payback rather than shorten it. It suits households that are out during the day and use most of their electricity in the evening.
Not hidden exactly — but frequently omitted, which amounts to the same surprise. These are the items most often left off a quote and billed later:
Scaffold hire
£600 – £1,200
Yes — always
DNO notification / G99 application
£0 – £150
Yes
Consumer unit upgrade
£400 – £800
If survey identifies it
Earthing / bonding upgrade
£150 – £400
If survey identifies it
Part P certificate
£0 – £150
Yes — legally required
Bird / pigeon proofin
£250 – £500
Optional, but ask
Scaffold extension (overrun)
£100 – £200/week
Should not arise on a planned job
Roof repairs found during install
Variable
Should be flagged at survey
“Is this price all-inclusive, and will anything be added between now and handover?” Get the answer in writing. A confident installer will give it without hesitation.
Stack the factors and the arithmetic becomes obvious rather than suspicious. Installer A quotes budget panels, a string inverter, and excludes scaffold. Installer B quotes premium panels, microinverters, and includes scaffold, a consumer unit upgrade and bird proofing.
Same roof. Same nominal 4kW. Genuinely different installations, and a gap of £2,000 or more that has nothing to do with either company being dishonest.
This is the case for comparing three quotes rather than one — not to find the cheapest number, but to see what the range even is for your property.
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Seven main factors: system size in kWp, panel brand and tier, inverter architecture (string, optimiser or microinverter), roof access and scaffold requirements, any electrical upgrade works, installer overhead and travel distance, and whether battery storage is included. Hardware accounts for roughly 45% of a typical quote — the rest is labour, access and administration.
The most commonly omitted costs are scaffold hire (£600–£1,200), consumer unit upgrades (£400–£800), earthing and bonding upgrades (£150–£400), and DNO application fees. These are rarely hidden deliberately, but they are frequently left off remote estimates. Ask for written confirmation that the quoted price is all-inclusive before signing.
Usually because it specifies different hardware or excludes items the other includes. A quote using budget panels with a string inverter and no scaffold line can look £2,000 cheaper than an all-inclusive quote for premium panels and microinverters on the same roof. Compare the specification and the inclusions, not the headline figure.
Yes. Slate roofs take longer to work with and carry more breakage risk than concrete tile, so labour is higher. Roof height and street access drive scaffold costs, which can vary by several hundred pounds between a bungalow and a three-storey terrace. Flat roofs need ballasted or A-frame mounting systems, which add hardware cost.
Only after confirming it covers the same scope. Check that scaffold, DNO notification, Part P certification and any electrical upgrades are inside the price, that the panel and inverter brands are named, and that warranty terms match. A cheap quote with three exclusions frequently finishes more expensive than a mid-priced all-inclusive one.
