Some new build homes do come with solar panels fitted — but many of those systems are sized to meet minimum building regulations, not to make a meaningful dent in your electricity bill. Before you accept whatever the developer has put on the roof, it pays to know what you're actually getting.
Do new build houses come with solar panels?
Not always — and the answer depends heavily on when the home was built and who developed it. For homes built before 2027, there's no blanket legal requirement to include solar. Developers have been installing panels on new builds to help meet the energy efficiency targets in Part L of the Building Regulations, but that's a carbon compliance tool, not a consumer benefit. The result: some homes get a meaningful array, others get a token installation that mainly exists to satisfy the SAP calculation.
That's changing. The Future Homes Standard, published on 24 March 2026 as Part L 2026 of England's Building Regulations, effectively mandates solar on the vast majority of new homes from 24 March 2027, with a transitional period running to 24 March 2028 for sites already under construction. The standard requires new homes to produce around 75–80% less carbon than a home built to 2013 standards — a target that can only realistically be met with rooftop solar and a heat pump. Solar Energy UK estimated the rules will apply to around 90% of new homes in England.
Scotland, Wales and Northern Ireland are following with broadly equivalent regulations on roughly aligned timetables, though devolved nuances apply.
So if you're buying a home being built now — before the 2027 cut-off — you may or may not have solar, and even if you do, the system may not be as useful as it looks.
Are new build solar panels any good?
That depends almost entirely on the system size. The Future Homes Standard's deemed-to-satisfy route specifies solar PV covering 40% of the dwelling's ground floor area. For a typical three-bed semi with a 42.5 m² ground floor, that works out at roughly a 3.4 kWp array — about eight panels. That's a reasonable minimum, and from 2027 it's what most buyers should expect as a baseline.
The problem is homes being sold today that were designed under the older rules. Before Part L 2026, the calculation was looser, and some volume developers fitted much smaller arrays — sometimes under 2 kWp — purely to satisfy the compliance model. A system that small will generate a modest amount of electricity but won't cover much of a typical household's daytime demand. You might offset the kettle and the fridge. You won't offset the washing machine, the dishwasher, and the EV charger you're planning to add.
Even under the new rules, the minimum-compliant 3.4 kWp is the floor, not the ceiling. A detached four-bed with plenty of south-facing roof could comfortably take 5–6 kWp. A developer fitting the minimum to a large house isn't doing you a favour — they're doing the least legally required.
What to check before you exchange
If the developer says solar is included, ask for specifics in writing before you commit. These are the questions that separate a genuine solar install from a compliance exercise:
- System size in kWp — anything under 3 kWp on a three-bed or larger home warrants scrutiny. Use our UK sizing guide to check whether the array is proportionate to the house.
- MCS certification — the installer must be certified by the Microgeneration Certification Scheme. This isn't optional: you need it to register for the Smart Export Guarantee (SEG) and any future government schemes. Ask for the MCS certificate number.
- Panel brand and warranty — reputable panels carry a 25-year performance warranty. Unnamed or unbranded panels are a red flag.
- Inverter specification — the inverter converts DC power from the panels to usable AC electricity. Ask whether it's a hybrid inverter (battery-ready) or a standard string inverter. A battery-ready inverter saves money if you add storage later.
- Who registered the system for SEG? — the Smart Export Guarantee pays you for surplus electricity you export to the grid. You need an MCS-certified install and a smart meter to claim it. Make sure the developer has registered the system, or that the paperwork is handed to you so you can do it yourself.
- Roof orientation and shading — south-facing is best; south-east and south-west both work well. Ask which slopes the panels are on and whether any nearby buildings or trees will cause shading. See our guide to how shade affects solar output for the detail.
The Smart Export Guarantee: make sure your new build is registered
Any surplus electricity your panels generate and don't use gets exported to the grid. Under the Smart Export Guarantee, your energy supplier pays you for that export. It's not a fortune, but it's money you're entitled to and that many new build buyers miss simply because the developer didn't hand over the paperwork.
To claim SEG, the system must be MCS-certified, and you need a smart meter that can record half-hourly export. Fixed SEG rates in mid-2026 typically run from around 4p to 15p per kWh, depending on the supplier and tariff. Variable and time-of-use tariffs can go higher at peak times. The electricity you import from the grid is currently capped at around 26.11p per kWh (Ofgem price cap, July–September 2026), which means every unit you use from your own panels is worth considerably more than the export rate — the case for maximising self-consumption is strong.
For a detailed comparison of current rates, see our guide to the Best Smart Export Guarantee Rates UK 2026.
Can I upgrade solar panels on a new build?
Yes — and in many cases it makes good sense. If you're buying off-plan, the best time to negotiate is before construction starts or early in the build phase. Adding extra panels at that stage is significantly cheaper than retrofitting later, because the scaffolding is already in place and the roof integration is straightforward.
If you've already moved in, retrofitting a larger system is still viable — the roof is new, which means fewer complications. The marginal cost of adding capacity to a minimum-spec FHS-compliant base (say, going from 3.4 kWp to 5 kWp) is relatively modest compared to the additional generation over a 25-year panel life. The 0% VAT rate on energy-saving materials, including solar panels, also applies to retrofit installs — confirm current eligibility at gov.uk before committing.
One practical consideration: check whether the developer has left conduit runs (cable ducts in the walls and loft) to allow for battery storage. If not, that's additional installation cost when you decide to add a battery later. It's cheap to put in during the build and expensive to retrofit.
When is the developer-fitted system good enough?
To be fair to new build solar: even a modest system on a well-oriented roof is better than no system. If the home has a south-facing roof, an MCS-certified install of 3–4 kWp, a battery-ready inverter and a properly registered SEG account, you're in a reasonable position. The panels will reduce your daytime grid consumption, you'll get paid for surplus export, and the system adds value to the property.
It's also worth remembering that new build solar is typically 15–25% cheaper to install per panel than a retrofit, because fitting during construction avoids scaffolding costs and roof penetration work. If the developer has passed that cost saving on — which isn't always guaranteed — the system may represent genuinely good value even if it isn't the largest it could be.
Where we'd push back harder: if the home is a four or five-bed detached with ample south-facing roof and the developer has fitted a 2 kWp system without battery provision, that's the minimum-compliance approach, and it's worth negotiating for more or pricing up a retrofit before you move in.
What about new builds that don't have solar at all?
If you're buying an older new build — say, one completed before the interim Part L rules pushed more developers towards solar — you're essentially in the same position as any other homeowner looking to add solar. The roof is likely in excellent condition, the property is well insulated (which means your electricity demand will be lower than an older house), and the planning and installation process is straightforward.
The honest answer is that the maths for solar on a well-insulated new build is often less compelling than on a draughty older property, because your bills are already lower. Run the numbers for your specific situation before assuming solar is a slam dunk. A typical sized system on a three-bed home might reduce electricity bills meaningfully, but the payback period varies considerably depending on your usage, tariff and how much of the generated electricity you actually use yourself rather than export at a lower rate.
If you want free, no-obligation quotes from MCS-certified local installers who can assess your specific roof and usage, use our free quote form — it takes a couple of minutes and there's no obligation to proceed. FairSolar is free to homeowners; you can see how we're paid here.
Frequently asked questions
Do all new build houses come with solar panels?
Not yet — but it's becoming the norm. From 24 March 2027, the Future Homes Standard effectively mandates solar on the vast majority of new homes in England. Homes built before that date may or may not have panels, depending on the developer and the planning consent in place.
Are new build solar panels any good, or just a tick-box exercise?
It varies. From 2027, the minimum required under the Future Homes Standard is roughly a 3.4 kWp system for a typical three-bed semi — that's a meaningful size. Homes built under older rules sometimes got much smaller arrays that generate relatively little. Always ask for the system size in kWp in writing before you exchange contracts.
Can I upgrade the solar panels on a new build?
Yes. If you're buying off-plan, negotiating additional panels before construction is the cheapest option because the scaffolding is already up. If you've moved in, retrofitting extra capacity or adding battery storage is straightforward on a new roof. Solar panels and batteries currently qualify for 0% VAT — check gov.uk for the current rules.
Will the new build solar panels be registered for the Smart Export Guarantee?
They should be, but check. The system needs to be MCS-certified and you need a smart meter to claim SEG export payments. Ask the developer for the MCS certificate and confirm who is responsible for registering the export tariff with your energy supplier — otherwise you could miss out on payments you're entitled to.
Does adding more solar panels affect my new build warranty?
It can do if work is carried out carelessly, but a properly installed MCS-certified system by a competent installer should not void your NHBC structural warranty. The NHBC warranty covers the building fabric for 10 years; always use an MCS-certified installer and notify your warranty provider before work starts to be safe.