For a typical UK home with a south-facing roof and decent daytime electricity use, solar panels usually pay back in 8–12 years and last 25 or more. Whether they're worth it for your home comes down to four things: your roof, how you use electricity, what you pay upfront, and what you can sell back to the grid. This guide walks through each one with real numbers, not marketing ones, so you can decide before you book a quote.
The honest summary: solar still works for most homes with a decent roof. But the case has narrowed since the original Feed-in Tariff ended in 2019, and the answer depends on your specific home.
What it costs and what you get
A 4kW solar system, the size most UK semis end up with, costs roughly £5,000–£7,000 installed. Add a battery and you're closer to £8,000–£12,000.
In return, you get electricity you don't have to buy from the grid, plus a small income from electricity you sell back. The maths only works once you understand four things about your specific home:
1. Your roof
This is the single biggest variable, and the one most installer quotes gloss over.
- Orientation. South-facing roofs generate the most. East- and west-facing roofs deliver around 80% of that. North-facing roofs rarely justify the cost.
- Pitch. A 30–40° angle is close to optimal. Flat roofs work but need mounting frames, usually at a small extra cost.
- Shading. Chimneys, neighbouring buildings, and tall trees reduce output more than people expect. A few hours of shade in the middle of the day can cut annual generation by 20–30%.
- Usable area. A 4kW system needs roughly 20m² of clear roof.
You can usually work out orientation from a satellite map. A good installer will model your specific roof using PVGIS or the MCS methodology and show you the numbers.
2. How you use electricity
Solar saves you the most money when you use the electricity as it's being generated. Anything you don't use gets sold back to the grid for a fraction of what you'd pay to buy it.
You get most from solar panels if you:
- Work from home
- Charge an electric vehicle at home
- Have a heat pump or electric hot water heating
- Run high-use appliances (dishwasher, washing machine, dryer) in the middle of the day
You won't get as much if the house is empty 9–5 and most of your electricity use happens after dark, unless you add a battery to shift daytime solar to evening use.
3. What you pay upfront
Costs vary by installer, system size, and roof complexity, but as a rule of thumb:
- 4kW system, no battery: ~£5,000–£7,000 installed
- 4kW system with a 5kWh battery: ~£8,000–£12,000
Two things worth knowing:
- VAT is 0% on residential solar in the UK until at least March 2027. Worth confirming with your installer that your quote reflects this.
- Financing changes the picture. A loan adds interest to the total cost, payback gets longer, but you're not parting with the cash upfront. We've covered borrowing options in our guide on: Raising capital for home improvements
- Get three quotes for the same system size before you decide. Quotes for "what fits on your roof" vary wildly, you want like-for-like.
4. What you sell back
Since 2020, the Smart Export Guarantee (SEG) has replaced the old Feed-in Tariff. Your energy supplier pays you for electricity you export to the grid.
SEG rates currently range from around 1p to 15p per kWh depending on the supplier and tariff. The supplier you buy your electricity from is often not the best one to sell to, they're separate decisions. Worth checking, and worth checking again every year or two, because rates change.
For most homes without a battery, around 60% of solar generation gets exported. With a battery, that drops to 20–30%, you use more of what you generate yourself.
A worked example
Let's run real numbers for a three-bed semi in the Midlands. South-facing 30° roof, two adults working hybrid (home 2–3 days a week), no electric vehicle.
- System: 4kW, no battery
- Installed cost: £6,000
- Annual generation: ~3,600 kWh
- Self-consumed: 40% × ~27p saved on bills = ~£390/year
- Exported: 60% × ~7p SEG = ~£150/year
- Total annual benefit: ~£540- Payback: ~11 years
Now change one variable, same household, but they charge an EV at home on a daytime tariff:
- Self-consumption rises to ~60%
- Annual benefit climbs to around £700
- Payback drops to around 7 years.
These numbers move with electricity prices, SEG rates, and how your usage changes. The point isn't the precise figure, it's that the case is much stronger when you can use the electricity as it's generated.
What it does to your EPC
Solar typically lifts a UK home's EPC by one band, for example, D to C.
Why that matters:
- Some lenders offer better mortgage rates on properties at EPC C or above
- Energy performance is becoming a bigger factor in resale appeal
- For landlords, MEES rules mean the minimum acceptable rating is tightening
A one-band lift isn't guaranteed. EPCs depend on a lot of things: heating system, insulation, glazing, and solar is only one of them. For more on this, read: How to improve your EPC rating.
Things people don't tell you
Panels degrade. Output drops by around 0.5% per year. After 25 years, expect 85–90% of day-one output.- Inverters don't last as long as panels. Most need replacing around year 10–15. Budget around £1,000 when you do the maths.- Tell your buildings insurer. Some require notification, and a few add a small premium.- Bird-proofing. Pigeons nest under panels. A mesh kit costs a few hundred pounds and saves a much bigger problem later.- The roof needs to be in good condition first. If it'll need re-roofing in five years, the panels have to come off and go back on. Cheaper to do roof works first.
When solar probably isn't worth it financially
- North-facing only roof
- Heavily shaded site
- You're moving in the next year or two, payback is too long, though there's some evidence solar adds modestly to resale value
- Listed building or a strict conservation area without consent
- Roof needing imminent replacement
A simple checklist before getting quotes
1. Confirm your roof's orientation, pitch, and condition
2. Note when you actually use most of your electricity
3. Get quotes from three MCS-certified installers (MCS certification is required for SEG eligibility)
4. Ask each installer to show their generation estimate using PVGIS or MCS methodology, they should explain how they got the number
5. Compare like-for-like system sizes, not "what fits"
6. Check what SEG rates are available, including from suppliers you're not currently with
7. Decide on a battery separately — run the maths with and without
The bottom line
For most UK homeowners with a decent roof and some daytime electricity use, solar still pays back inside the panel warranty period. The honest answer is that it depends on your numbers, not the installer's.
Solar isn't a silver bullet. It's one of several upgrades, alongside insulation, draught-proofing, and a good heating system, that together make a home cheaper to run and easier to sell. The case is strongest when you treat it as part of a wider plan, not a one-off purchase.
Before you book any quotes, do you know how much of your electricity you actually use during daylight hours? That single number changes the answer more than anything an installer will tell you.
This article is for general information only and does not constitute financial or technical advice. Costs, tariffs, and policy change, confirm current numbers before making a decision.
Researching a home? Check its details on Property Looker for EPC rating, local property data, and surveyors who can assess roof condition before you commit.