Getting three solar quotes is the right move — but only if you know how to compare them properly. Put two quotes side by side without understanding what each line means, and you can easily pay £1,000–£3,000 more than you need to, or worse, pick the cheaper one that's actually missing half the job.
This guide walks you through exactly what a solid solar quote should contain, why quotes for nominally the same system can look so different, and the specific things to check before you sign anything.
Why getting three quotes matters
The Energy Saving Trust recommends getting at least three quotes from MCS-certified installers before committing to any solar installation, because prices genuinely vary between companies for the same system size.
The keyword there is same system. As you'll see below, many quotes that look comparable at first glance are not comparing like for like at all. You need at least three quotes to see the pattern — and to have enough information to push back sensibly on any of them.
One practical note: FairSolar is free to you as a homeowner. Installers on the platform are vetted and MCS-certified. You can use the free quote form to get matched with local installers, then use this guide to compare what comes back.
What should a solar panel quote include?
A properly itemised quote should cover every component of the job. If you receive a single headline price with no breakdown, ask for one. Any installer who refuses to provide a line-by-line quote is not one you want on your roof.
Here is what you should expect to see:
- Panel brand, model number and rated wattage per panel — "10 x 400W monocrystalline panels" is not enough. You want the manufacturer's name and the specific model, so you can look up the datasheet and the warranty yourself.
- Total system size in kilowatt-peak (kWp) — this is the headline output of the system. Check that the panel wattage multiplied by the number of panels matches the figure quoted. Mismatches do appear in real quotes.
- Inverter brand and model — the inverter converts DC power from the panels into AC electricity your home can use. It is also the component most likely to need replacing during the system's lifetime, so the brand matters. Cheap inverters and quality inverters have very different lifespans and price tags.
- Expected annual generation in kWh — a reputable installer will provide a generation estimate based on your specific roof orientation and location, not a generic national average.
- Mounting system and roof fixings — labour and materials for physically attaching panels to your roof.
- Scaffolding — this is a common omission from cheaper quotes and can cost several hundred pounds. Confirm it is included.
- Electrical work and consumer unit assessment — some older homes need the consumer unit (fuse board) upgraded to handle solar. Ask whether this is included or, if the installer cannot confirm until survey, whether it will be quoted separately.
- DNO notification — your Distribution Network Operator must be notified of any new generation system. Most installers handle this as standard; check that this is not an extra charge.
- MCS installation certificate — you need this to register for Smart Export Guarantee (SEG) payments. Without MCS certification, you cannot access SEG, and most panel and inverter manufacturers require evidence of a certified installation to honour their product warranties.
- Workmanship warranty duration — MCS-certified installations come with a five-year workmanship guarantee backed by the scheme. Quality installers often offer more. A two-year workmanship warranty and a ten-year warranty are not the same product.
- Panel and inverter product warranties — most modern solar panels carry a 25-year performance guarantee; inverter warranties are typically five to twelve years depending on brand.
- VAT confirmation — VAT on domestic solar installations is zero-rated until 31 March 2027, so all quotes should already reflect this. Any quote that adds 20% VAT on top needs explaining.
Why are solar quotes so different from each other?
This is the question most homeowners ask after opening three envelopes. A gap of £1,500–£3,000 between two quotes for what sounds like the same job is genuinely common, and it usually comes down to one or more of the following:
Different system sizes
One installer may have quoted you a 3.6kWp system; another a 4.2kWp. Ten panels could be 3.8kW or 4.5kW depending on the wattage of each panel. Always compare total kW and the estimated annual generation figure in kWh — not just how many panels appear on the quote.
Different panel and inverter quality
Panels are only around 35–40% of the installed cost of a solar system — the rest is inverter, mounting, electrical work, scaffolding, and labour. A quote that looks cheaper often reflects a lower-tier panel brand or a budget inverter, not better value. Ask for the specific model number and check the manufacturer's warranty terms before deciding the cheaper quote is actually cheaper over its lifetime.
Things left out of the price
Some quotes look competitive but exclude scaffolding, DNO application fees, or any consumer unit work that turns up at survey. A quote missing these line items is not a lower price — it is an incomplete price. The cheapest quote is often missing a line item that becomes a surprise cost at installation.
Different savings and payback projections
Watch out for payback calculations that assume aggressive electricity price inflation of 3–5% a year to make the numbers look compelling. A more conservative projection using current rates gives you a more honest picture. Be sceptical of any projection that doesn't show you the assumptions clearly.
How to compare solar panel quotes side by side
Once you have your quotes itemised, put them in a simple table with the following columns so you're genuinely comparing the same things:
Total installed cost · System size (kWp) · Cost per kWp · Annual generation estimate (kWh) · Panel brand and model · Inverter brand and model · Scaffolding included? · DNO notification included? · Workmanship warranty (years) · Panel warranty (years) · Inverter warranty (years) · MCS certificate included?
Cost per kWp is your most useful single number for comparing like for like across different system sizes. According to MCS data, the average installed cost per kW in England in April 2026 was around £1,565 — use that as a benchmark when assessing whether a quote is in the right ballpark or suspiciously high or low. For a full breakdown of what homes of different sizes typically pay, see our guide to Solar Panels Cost UK 2026: What Homes Actually Pay.
The inverter question most homeowners forget to ask
The inverter is the component most likely to need attention or replacement during the system's 25-year life, yet it's often the least scrutinised line on a quote. Ask each installer to name the inverter brand and look it up. A quality inverter with a strong warranty and readily available UK servicing is worth paying for — a cheap inverter that fails at year nine means a repair bill that can wipe out months of savings.
If any quote includes a battery, also ask whether the battery is fully compatible with the specified inverter. A mismatched battery and inverter can lose efficiency every year — and that loss compounds over time.
Check the installer's credentials, not just the price
All installers quoting through FairSolar are MCS-certified — but if you are collecting quotes independently, always verify this. MCS certification means the installer has been assessed against quality and competence standards, and their installations must be registered on the MCS database. You also need an MCS-certified installation to register for the Smart Export Guarantee, the government-backed scheme that pays you for surplus electricity you export to the grid. SEG export rates currently range from around 3p to 25p per kWh depending on the tariff — see our guide to the Best Smart Export Guarantee Rates UK 2026 for the current picture.
Also check whether the installer is a member of a consumer code such as RECC or HIES. These give you access to an independent complaints process if things go wrong — something that's worth having on a job that could cost upwards of £7,000.
When the cheapest quote is fine — and when it isn't
If three quotes specify identical or near-identical kit, all include scaffolding and DNO notification, and all come from MCS-certified installers with solid reviews, then the cheapest of the three is probably the right choice. The problem is that's rarely the situation. More often, the cheapest quote has cut something — a lower-tier panel brand, a cheaper inverter, or a missing line item that will surface later.
The goal isn't to pick the cheapest quote. It's to understand exactly what each quote includes, and then choose the best value for your specific home and circumstances. Sometimes solar genuinely isn't the right move — if your roof faces north, is heavily shaded, or is in poor condition, the economics may not stack up however good the quote looks. Being honest about that is important, and a good installer will tell you the same.
If you want to understand what a fair price looks like for a home like yours before you start, our guide to Solar Panel Payback Time UK 2026 runs through the realistic numbers in plain English.
Ready to see what installers actually quote for your home?
The best way to put this guide into practice is to get real quotes in front of you. FairSolar connects homeowners with vetted, MCS-certified local installers — it's free to use, there's no obligation to proceed, and you'll have something concrete to compare. Start your free quote request here and use this guide to work through what comes back.
Frequently asked questions
How many solar quotes should I get?
The Energy Saving Trust recommends getting at least three quotes from MCS-certified installers. Three gives you enough data points to spot outliers — whether unusually high or suspiciously cheap — and to understand what a fair price for your specific home and system size actually looks like.
Why are my two solar quotes so different in price?
Most quote differences come down to one or more of: different system sizes (check kWp, not just number of panels), different panel and inverter brands, or things left out of the cheaper quote — such as scaffolding, DNO notification, or consumer unit work. Always ask for a full itemised breakdown before comparing prices.
What should a solar panel quote include as standard?
A complete quote should specify the panel brand and model, inverter brand and model, total system size in kWp, expected annual generation in kWh, scaffolding, electrical work, DNO notification, and the workmanship and product warranty terms. It should also confirm 0% VAT is applied and that an MCS installation certificate will be issued.
Does the cheapest solar quote usually win?
Not reliably. The cheapest quote often reflects a lower-tier panel brand, a budget inverter, or missing line items like scaffolding that will be charged separately later. Compare quotes on cost per kWp and the full specification, not just the headline price.
Do I need an MCS-certified installer to get SEG payments?
Yes. You need an MCS-certified installation and an export-capable smart meter to register for the Smart Export Guarantee (SEG), the scheme that pays you for surplus solar electricity exported to the grid. Without MCS certification, most panel and inverter manufacturers may also refuse warranty claims.