What makes some solar quotes so cheap compared to others in 2026?

After extensively researching quotes for solar panels on your home, you find most sit within a certain range - but there’s often one that has you wondering, why is that quote so cheap?

For a typical 4kW, 8 panel system with a 6kWh battery, installed prices across the market sit between £7,500 to £12,500. You may wonder: why is my solar quote so cheap compared to others? How can the same job have a difference between £2,500 to £5,000, just based on the installer?

Before you get stuck in a research rabbit-hole, we wanted to offer a guide that goes behind the scenes of solar estimates. In this piece we will cover:

🏠 What different roof types mean for your quote

🔋 Why the cost of kit doesn’t influence your price too much

🧑‍🔧 How low prices drive low wages - and low quality

📋 A checklist of questions to ask any installer before committing any cash

Why this matters in Walthamstow

A lot of houses that are joining the Walthamstow Power Station Project don’t have simple pitched roofs that you can bolt a standard mounting rail to, then move on. Many have a mix of flat and pitched roof sections; Victorian or Edwardian terraces with pitched slate roof at the front, and flat felt or GRP (Glass Reinforced Plastic, or fibreglass) on an extension at the back. More than an aesthetic quirk, this requires a certain level of expertise and understanding in the installation.

Having fitted solar systems on a variety of roofs in Walthamstow (including the second wave on Lynmouth Road, whose roof types were generally the reason they were left out of the first wave of installs), POP and our team of locally-based tradespeople understand the kit and the cost of labour to make sure this kind of install generates the same high-quality results as a cookie-cutter roof.

How does your roof impact your solar quote? 

Part of your estimate includes the cost of designing the solar system, so if you live in a typical property with a pitched roof, the cost of designing a system is low as it’s almost a copy-and-paste job. We often call this the cookie cutter approach. As soon as a flat roof is involved (or a mix of roof types), things get a little more complicated.

On a pitched roof, panels are fixed under the tiles or slates, into the rafters. The roof structure itself takes the load, and the fixings resist wind uplift. On a flat roof, you can’t pierce the material of the roof, as it risks leaking. Flat roof arrays are usually ballasted instead: the panels sit in tilted trays that are weighted down with purpose-made ballast blocks or paving slabs, which are held in place by their own mass and friction instead of bolted into the rafters.

Whilst it sounds simple, it isn’t: a ballasted array adds a large load of weight to a roof structure that wasn’t designed with solar in mind. Designing a solar system for a flat roof safely needs:

✔️ A proper structural assessment of the existing roof deck and joists to confirm it can safely bear the weight of the trays, panels, and ballast - and more.

✔️ Wind-loading calculations specific to the building’s height, location and exposure. A flat roof creates uplift and turbulence around parapets and edges that a standard pitched-roof calculation doesn’t capture. Get this wrong and an array may well lift off in windy weather.

✔️ Careful positioning to keep ballast in an optimal position: away from roof edges and upstands, spread across the roof not concentrated in one place, and avoiding the extra lift at the edge of the roof.

✔️ Coordination between flat and pitched sections so cable runs, isolators, inverters and the transition between the two roof types are all done properly.

These are the differences between a system still safely generating energy and delivering savings after 20 years, and a system becoming a structural or safety problem long before then. It takes design time from someone who knows what they’re doing before a single panel is placed on the roof. Once your solar system is designed, the next consideration is the cost of kit.

Does bulk buying panels save money on solar projects? 

Solar panels, inverters, batteries, and all the kit needed to assemble a renewables system, are traded on global markets. The first half of 2026 has seen the highest number of solar installs in a six-month period since 2011, so you can assume there’s a lot of panels being imported into the UK. A panel fitted on an Edwardian terrace in Walthamstow was likely made in the same factory, on the same production line, as a panel fitted on a new-build estate in Sussex ordering hundreds of panels at once. Economies of scale exist in manufacturing; but the benefits are generally captured by the factory, not the installer on your roof.

Once a distributor is buying pallets of panels and battery units by the container-load, the marginal saving compared to ordering ten systems each month is relatively small. The 45-50% of a typical install’s cost that goes to hardware is loosely the same whether you’re a two-person firm doing one job a week, or a national firm doing fifty.

This matters when you’re weighing up quotes between competitors. When the kit (the panels, the battery, and all the hardware that connects them) is the same, it’s likely costing the same everywhere. So when there are thousands of pounds difference between different quotes - where are those cost cuts being made?

Do cheap solar quotes affect the quality of work?

If the kit costs the same, then price differences come from the human part.

While a boiler gets replaced every 10-15 years, solar and battery systems are designed to sit on a roof and run, largely unattended, for 25 years. The quality of the workmanship (from the flashing under mounting feet, to the cable management in a loft that will heat up over summer, to the quality of the DC isolator or the post-sales support in case of an issue) determines whether this investment operates like a 25-year asset, or becomes a source of leaks, faults, disputes and stress.

Around 50% of a renewable system price covers people: labour, design time, scaffolding, electrical certification, health & safety compliance, project management and ongoing customer care. This is where costs are cut. 

This can show up in a couple of ways.

A rush job 

A crew trying to install solar panels on multiple roofs a day instead of one, is a crew rushing. And they are rushing careful DC isolation, correct earthing, safely working at a height, and MCS-compliant certification. Poorly installed electrical work can mean a failed MCS inspection, but it isn’t always obvious on day one. It can range from underperformance you don’t notice for months through to a fire risk from poor DC isolation (which may void your warranty), that a rushed rooftop connection was never built to prevent.

Overlooking complexity 

A contractor paid a flat day-rate, regardless of how complex a roof or job turns out to be, is only incentivized to move fast and get the job done; not move carefully as they consider whether the initial design will work for this installation. It can leave you with a system that works, but not as well as you were quoted. It could mean design decisions that should’ve been made earlier, are made in reaction to the situation on the roof, which are difficult and expensive to unpick later. It can mean wrong panel angles, unaccounted-for shading, undersized batteries, or warranty claims that are complicated by the difference between design and reality.

Hoping over anticipating 

A quote that skips over a proper structural survey, or includes scaffolding priced to the bone, is a quote betting that nothing unusual will be found once someone’s up on a roof. Taking that bet can go many different ways. It can mean nothing but a straightforward install. It can mean discovering mid-job that a flat roof can’t take the load as planned, meaning delays, extra costs or remedial work that wasn’t budgeted for. It can even mean leaks, a sagging deck, or ballast that shifts in high wind and risks the whole system; the kinds of faults hard to trace back to a single source.

Poor pay for people

If a tradesperson has the choice between working for a fast-turnaround and lower pay outfit, or working for themselves in the area they choose, which do you think they’ll prefer? As the old adage goes, you get what you pay for, and investing in a system for the next quarter-century is definitely an investment you want to make with an expert at their craft, who will see a fair wage for their work. 

Delivering for today, not investing in the future

Solar and battery regulations and finance are changing fast. With VAT cuts, changing Boiler Upgrade Scheme grants, new financing options, and the Warm Homes Loan Scheme expected autumn 2026, what a system costs is shifting. An installer who doesn’t have time to keep up with these changes isn’t just behind; they might be missing out ways to bring your costs down. As you’re investing in a system for the next 20+ years, you want an installer whose knowledge is as current as the technology they’re fitting.

None of this is necessarily dishonest. But this is generally where savings are squeezed from. Complexity, access, and site conditions are consistently what swings price within a postcode: not the panels themselves.

This is the part that’s easy to miss when you’re comparing quotes side by side. It’s easy to strip out structural surveys, skip roof-specific calculations for flat roofs and squeeze subcontractors to deliver at pace, for a lower price on a page. What’s harder, and what a bare bones quote cannot cover, is the margin needed to do the design work properly, to stand behind the quality of workmanship, and to still be a functioning company in ten to fifteen years, if a customer calls with a fault under warranty.

What should I ask solar installers before accepting a quote?

You can’t inspect the quality of labour from a PDF quote, but you can ask what it’s built from. The answers to the questions below tell you more about what a “cheap” number has cut more than any design or quote will.

Before you ask any installer anything: source multiple quotes from different scales of installer. Make sure you have at least three quotes, including one from a large national installer and one from a small local outfit. The more quotes you have, the better you can understand the range; and which are outside the average range.

Questions to ask

• Has my roof been assessed, or is your design based on a standard roof? This is incredibly important, especially if you’ve got a flat roof. You want to make sure that the system that has been designed accounts for the age and structural integrity of your roof before kit is ordered, so decisions are made in advance, not on the fly.

• Is this design based on my home, or is it a standard package? There’s nothing necessarily wrong with a standardised package, but you’ll want to be sure that any quirks or unique features of your home have been accounted for at the design stage.

• Who is doing the install, and what is their expected workload around the date of my installation? Knowing whether tradespeople are employed or external contractors, local or transported in is useful; as is knowing how squeezed their time is. It helps you better understand how much you’re investing in the quality of work (and your long-term return on investment) compared to short-term costs.

• Is scaffolding or any other equipment included in the quote? Make sure you don’t get any sudden surprises closer to your installation date by double checking that the quote is inclusive of everything the team will need to get your system installed and running on the timescale they promise.

• Does this quote include any available grants? Can you advise me on financing options in my area? There is a plethora of grants and loans available that vary by area, with more (such as the Warm Homes Loans) due to launch as soon as Autumn 2026. You want to ensure your installer is making the most of these funding options to help you keep your upfront investment lower without cutting the quality of workmanship.

• How long is the workmanship warranty? Make sure you distinguish between manufacturers and workmanship warranty - and get an idea on how the process works if something goes wrong. You want to know the process before an emergency crops up.

• What happens if something goes wrong after installation? Will you monitor the system? The quality of customer care you can expect in five, ten, fifteen years down the line is key. You want to be sure the person at the other end of the phone or email will be as friendly and available in your hour of need, as they are when they’re trying to land your sale.

Now you know that it’s the complexity of the job (including roof type), and the investment in labour and planning that sets quotes apart, you should have what you need to make an informed decision on how to differentiate between solar installers, and to find who is right for you.

Once you’ve got an estimate from POP, we’re happy to not just walk you through your design and answer any questions you may have; we’re also happy to delve into the details of comparing other quotes so you can make a choice based on the total investment of renewables, not just the upfront cost.

Get a free, no-commitment estimate

A fairer energy future starts on your street. If you want to continue (or start) the conversation of what fairer and affordable energy would look like on your home, get an estimate or drop us an email on hello@pop.energy to see how solar, batteries and heat pumps could cut your bills and increase your energy security.

Why do solar quotes for the same size system vary so much?

The cost of kit (panels, inverters, etc) is about the same everywhere, and generally makes up 45-50% of a quote. The other 50% covers people’s time and expertise: design, labour, scaffolding, certification and customer service. If any cuts are being made, it’s to the quality and time spent on this.

Is a cheaper solar quote always a red flag?

Not necessarily, but it’s worth understanding where the saving comes from. If the kit is the same cost everywhere, a lower price usually means less time spent on design, survey work, or labour, which isn’t always visible until problems emerge, years later.

Does my roof type affect my solar quote?

Yes. A standard pitched roof is close to a ‘cookie cutter’ copy-paste design job, so it’s cheap and easy to quote. Flat roofs, or a mix of pitched and flat roof (common on Victorian and Edwardian extensions) need additional wind-loading calculations and ballast positioning, which takes more time and can increase the price.

Does buying panels in bulk make a quote cheaper?

Not by much for the installer. Panels are traded globally, and economies of scale mostly benefit the manufacturer - not the people fitting them on your roof. A two-person local firm and a dozens-of-jobs-a-day national firm are usually paying similar prices for the same kit.

What are the risks of accepting a cheap quote?

Risks can range from underperformance you might not notice for months, to failed MCS certification, through to leaks or a shifting roof structure in high winds - which can be costly to remedy. None of this is necessarily dishonest; it's just where corners get cut when quotes skimp on proper design and quality of work. 

How many solar quotes should I get before choosing an installer?

The only limit is your imagination - although we recommend at least three, including one from a large national installer and one from a small local outfit. That range helps you spot which quotes are the ‘norm’ and which are outliers.

What's the difference between a manufacturer's warranty and a workmanship warranty?

The manufacturer's warranty covers faults in the panels or battery themselves. The workmanship warranty covers the quality of the install: wiring, mounting, and roof work. Always ask about both, and how the claims process works for each.

Are grants and financing options included in a solar quote?

They should be. Support like the Boiler Upgrade Scheme and the upcoming Warm Homes Loan Scheme (expected autumn 2026) can lower your upfront cost, and a good installer should be able to advise on what's available in your area.