A solar PV system for an ordinary UK home typically costs £6,000–£8,500 installed in 2026 for the most common 3.5–4kWp size, rising to £8,500–£12,000 for a larger 5–6kWp array on a bigger house. A small 3kWp system on a flat or terrace can come in from around £4,500. None of those figures include a battery — add one and you're looking at a further £4,000–£8,000 on top, depending on capacity. The whole package, equipment and labour together, is currently zero-rated for VAT, which is doing more to keep prices down than any grant on offer.
But the number that actually decides whether solar makes sense for a given house isn't the quote. It's whether the roof is the right shape, the right age and facing the right way to make the investment pay back inside a sensible timeframe — and that's a judgement most sales visits aren't set up to make honestly, because the person quoting is also the person who benefits if you say yes.
I assess the condition and performance of buildings for a living; I don't sell or fit solar panels, so I've no stake in whether you go ahead. That's useful here, because the question worth asking before the one about price is a straightforward surveying one: is this roof, on this house, actually a good candidate.
The short answer
Figures below were checked on 30 July 2026 against Checkatrade, MyBuilder and NimbleFins' 2026 cost guides, cross-referenced against Energy Saving Trust and HomeOwners Alliance figures. As with most trades in this series, Kent, Sussex, Surrey and London trend above the national average quoted here.
| System | Typical cost (2026) | What's included |
|---|---|---|
| 3kWp — flat or small terrace | £4,500–£6,500 | Panels, inverter, mounting, scaffolding, MCS commissioning |
| 3.5–4kWp — 3-bed semi (most common) | £6,000–£8,500 | As above; 10–12 panels, roughly 26m² of roof |
| 5–6kWp — 4-bed detached | £8,500–£12,000 | Larger array, possibly a higher-spec or 3-phase inverter |
| Add battery storage, any system | +£4,000–£8,000+ | 5–15kWh battery, hybrid inverter or retrofit AC coupling |
The whole installed package — panels, inverter, battery, scaffolding, cabling and labour, bought as one install contract — carries 0% VAT until 31 March 2027, after which the rate is due to rise, most likely to 5%. That's an automatic 20% saving against the standard rate while it lasts, and it applies whether or not you add a battery. A standalone battery fitted to an existing system also now qualifies, following a 2024 rule change.
What drives the price
System size. Cost scales roughly with capacity: current benchmarks sit around £1,800–£2,100 per kWp installed, so a 4kWp system and a 6kWp system are genuinely different jobs, not the same job with two more panels.
Panel tier. Budget panels from mainstream manufacturers run under £100 each before installation; premium high-efficiency panels can be £250 or more. The difference shows up in roof space needed for a given output, not necessarily in longevity — most reputable panels now carry 25–30 year performance warranties regardless of price point.
Scaffolding and access. A straightforward two-storey pitched roof is quick to scaffold; a hip roof, a dormer, or a house on a slope adds labour and access equipment. Combining the job with a re-roof or gutter replacement that needs scaffolding anyway is a genuine way to save.
Inverter type. A basic string inverter is the cheapest option; a hybrid inverter that's battery-ready from day one costs more upfront but avoids a second inverter swap if you add storage later.
Battery storage. This is the single biggest swing in the whole quote, and it's optional — a system without a battery is a perfectly complete, functioning installation, not a compromise.
Region. Kent, Sussex, Surrey and London trend above the national figures quoted here, in line with most trades in this series.
Do you actually need it, and is your roof ready?
Orientation and pitch matter, but less than most sales pitches suggest. South-facing is best, but east- or west-facing roofs only lose around 15–20% of annual output, and southeast or southwest loses barely 2–5%. The ideal pitch is 30–40°, which covers most UK roofs, but anything from roughly 10–60° still works, just with a modest efficiency penalty. What actually kills a project isn't orientation or angle — it's shading. A roof shaded by a mature tree or a neighbouring building for a meaningful part of the day will underperform regardless of how well it faces.
The question I'd put ahead of orientation, though, is one that doesn't come up in a sales visit: how much life is left in the roof covering itself. Panels are light, at roughly 15–20kg/m², and a competent installer won't damage a roof that's in good condition to fit them. But if the tiles or felt underneath only have 10–15 years of service life left, you're setting up a second bill down the line — removing and refitting a working array typically adds £500–£1,500 to the cost of a re-roof that would otherwise be straightforward. It's a five-minute check for anyone who knows what to look for, and it's worth doing before the panels go up, not after. If you're not sure how much life your roof covering has left, a drone roof survey is a cheap way to find out without scaffolding.
Structural loading is rarely an issue on a modern roof built to current span tables, but it's worth a second look on an older or already-stressed roof structure, particularly if you're adding an indoor battery too — a 10kWh unit can weigh 80–100kg and needs somewhere solid to sit.
On planning: most roof-mounted installations are permitted development, needing no application, provided panels don't rise above the ridge or project more than 0.2m from the roof slope. In a conservation area, the one added restriction is that panels can't go on a wall or roof slope fronting a highway. Listed buildings are a different matter entirely — permitted development doesn't apply, and you need listed building consent before fitting anything, on any grade of listing, whether or not the work would otherwise be trivial. Fitting without consent is a criminal offence, not a paperwork formality.
On the numbers: a typical system without a battery only lets you use directly, or "self-consume", something like 40–50% of what it generates, because most generation happens in the middle of the day when a lot of households are out or using little power. The rest is exported at Smart Export Guarantee rates — anywhere from around 3p to over 30p/kWh in 2026 depending on supplier and tariff, averaging roughly 13p/kWh on flat-rate deals, well below the 24–28p/kWh most households currently pay to buy electricity back. On that basis, a 3.5–4kWp system without a battery typically pays back in around 8–12 years; adding a battery improves self-consumption but usually stretches the payback closer to 12–15 years once its own cost is factored in, even though it earns more from the generation you already have. There's no shame in skipping the battery on year one and adding it later once panel costs have already been recovered.
One genuine grant is worth flagging: ECO4 can fund solar panels in full, alongside other measures, for low-income households in a home rated EPC D–G, typically worth £5,000–£8,000 for a 4kWp system. The scheme is currently due to close on 31 December 2026 with no confirmed direct successor, so it's worth checking eligibility with your energy supplier or council sooner rather than later if you think you might qualify.
What I'd watch for in a quote
- MCS certification for both the installer and the equipment. Without it you can't register for the Smart Export Guarantee, and some home insurers and mortgage lenders will want to see the certificate.
- Roof condition assessed, not assumed. A reputable installer should ask about the age of the covering, not just measure for panels.
- An insurance-backed warranty that survives the installer going out of business, standard with MCS certification but worth confirming in writing.
- An itemised quote separating panels, inverter, battery, scaffolding and making good, so you can compare it properly against another quote.
- No pressure to add a battery on the day. It's a genuinely separate decision with its own payback maths, not an accessory.
Questions I get asked
Do I need planning permission for solar panels? Most roof-mounted installations fall under permitted development and need no application, provided panels don't project above the ridge or more than 0.2m from the roof slope. Conservation areas add one restriction — no panels on a wall or slope fronting a highway. Listed buildings need listed building consent regardless; fitting without it is a criminal offence.
Will solar panels damage my roof, or do I need to replace the tiles first? A competent installer shouldn't damage a roof in good condition. The real risk is timing: if the covering only has 10–15 years left, you'll likely pay to remove and refit the array when it's re-covered. Worth checking the covering's remaining life before panels go up, not after.
Is it worth adding a battery? Depends on your usage pattern. Without one, a typical home self-consumes 40–50% of what it generates and exports the rest at SEG rates below the price of buying it back. A battery improves that but adds £4,000–£8,000 and usually pushes payback from 8–12 years to nearer 12–15. It suits evening-heavy, daytime-idle households best.
How much can I earn from the Smart Export Guarantee? Rates in 2026 range roughly 3p–30p/kWh depending on supplier and tariff, averaging around 13p/kWh on flat-rate deals. A typical 3.5–4kWp system without a battery might earn £150–£300 a year in export payments. You can use a different supplier for export than for import, so it's worth comparing both separately.
Solar panels are a fabric-and-roof decision as much as an electrical one, and that's where an independent read earns its keep — whether the covering has the years left to justify the investment, whether the structure's happy with the extra load, and how the array fits alongside other retrofit measures if you're weighing several at once. A retrofit assessment looks at the whole picture rather than just the roof a quote is trying to sell you. Call 07946 618203 or get in touch and I'll give you a straight read before you commit.
Small print. This guide is general information, not advice on a specific property, and it doesn’t replace a proper roof and structural assessment and a written quote for your own home. Prices were researched and correct to the best of my knowledge on 30 July 2026; costs, VAT rules and export tariffs move and vary by region, property and supplier. Always get at least three written quotes, and confirm MCS certification before signing anything.