If your new build has solar panels already fitted, you own a potentially valuable asset — but only if you know what you've got and take a few key steps to activate it. Many new-build buyers find the developer's handover pack glosses over the solar system entirely, leaving them unsure whether it's properly certified, whether they're owed money for the electricity it exports, and whether adding a battery is worth it.
What do I actually have on my roof?
Most new-build solar systems are between 3kWp and 4kWp in size — enough to cover a meaningful share of a typical household's electricity use. But the size is only part of the picture. What matters most is whether the system is MCS-certified, because that single fact determines almost everything else you can do with it.
MCS (the Microgeneration Certification Scheme) is the UK's quality mark for small-scale renewable energy. It certifies the installer, the equipment, and the individual installation itself. Without an MCS certificate, you cannot register for export payments, and you may find it harder to claim manufacturer warranties or satisfy a future buyer's solicitor.
The first thing to do is locate your handover pack and look for the MCS Installation Certificate. It should show your address, the installer's MCS-certified business name, the date of installation, the system size in kWp, and the panel and inverter makes and models. If it isn't in your pack, ask the developer in writing — they should be able to provide it.
You can also independently check whether your system is registered on the MCS Installations Database at certificate.microgenerationcertification.org — just search by your address.
For a broader checklist of what you should have in your solar paperwork, our guide on buying a house with solar panels runs through exactly what to look for — much of it applies equally to new builds.
What if the panels aren't MCS-certified?
It does happen. Developer-installed panels may not carry an MCS certificate if they were fitted as part of the building's construction process rather than by a specialist MCS-certified solar installer. Without it, you cannot register for the Smart Export Guarantee (SEG) — the scheme that pays you for electricity you send to the grid.
If your system isn't MCS-certified, contact the developer and ask them to rectify it. If the system was installed by a subcontractor who is MCS-certified, the certificate may simply have been mislaid rather than never issued. If the installer genuinely wasn't MCS-certified, getting the system retrospectively certified is difficult and sometimes impossible — this is worth pursuing with the developer as a warranty issue before your snagging period closes.
How do I register my new build solar panels for SEG payments?
The Smart Export Guarantee (SEG) is the scheme you need to register for. According to Ofgem, any eligible generator can apply for a SEG tariff with any licensed electricity supplier — and crucially, your SEG supplier doesn't have to be the same company you buy your electricity from.
To register, you'll need to tick these boxes:
- An MCS Installation Certificate — this is the non-negotiable starting point. Without it, no SEG supplier will register you for export payments.
- A SMETS2 smart meter capable of recording half-hourly export readings. New builds often have one already fitted — check with your energy supplier if you're unsure. If not, you can request one for free.
- A chosen SEG licensee — compare tariffs before you apply. In 2026, flat-rate export tariffs run from roughly 4p to 15p per kWh, with some time-of-use tariffs paying more at peak times. Our guide to the best Smart Export Guarantee rates in 2026 explains the differences in plain English.
Once you've chosen a supplier, apply online through their SEG application page. You'll typically need your MCS certificate number, your smart meter serial number, your import MPAN (on your electricity bill), the system size and installation date, and your bank details. Most suppliers process applications within two to four weeks. Importantly, SEG payments are not backdated to your move-in date — they start from the date your application is accepted, so it pays to get this done promptly.
Also worth knowing: as Ofgem confirms, you can use entirely separate companies for your SEG payments, your electricity supply, and your gas supply. You're not locked in to any one provider.
Should I add a battery to my new build solar panels?
Adding a battery is the question most new-build solar owners come to fairly quickly — and it's a reasonable one. Without storage, the electricity your panels generate during the day is either used immediately or exported to the grid at the SEG rate (typically a few pence per kWh). A battery lets you store that surplus and use it in the evening, when you'd otherwise be buying electricity at the full import rate.
Whether a battery is worth it for your home depends on your usage pattern, system size, and how much you export. Households that are out during the day tend to export more and stand to gain more from storage; households that work from home often self-consume more of their solar already. Our guide to whether solar battery storage is actually worth it walks through the honest maths.
The good news on costs: under HMRC's VAT Notice 708/6, adding a battery to an existing solar system currently qualifies for 0% VAT — a rule that has applied to retrofit batteries since 1 February 2024. This rate is in place until 31 March 2027, after which it is expected to rise to at least 5%. So if you're planning to add storage, doing it before that deadline makes financial sense. Our guide on 0% VAT on solar panels and the March 2027 deadline has the full detail.
In most cases, adding a battery to an existing new-build solar system is technically straightforward. An AC-coupled retrofit battery works with almost any existing inverter, so you're unlikely to need to replace your whole system to add storage.
Other things worth doing in the first few months
Tell your home insurer. Solar panels are a material change to your property. Let your insurer know — most standard policies will cover them as part of the building, but it's worth confirming in writing so you're not caught out by a claim.
Find out what your inverter is telling you. Your inverter (usually a box on the wall inside, often in the loft or utility room) displays or logs how much electricity your system is generating. Many modern inverters have an app. Understanding your generation data helps you see whether the system is performing as expected and spot any issues early.
Note the warranties. Panels typically carry a 25-year performance guarantee; inverters usually have a 5–10 year warranty. Check the paperwork now, while the developer is still reachable, rather than when something goes wrong in year three.
Check whether your electricity tariff suits solar. If you're on a flat-rate import tariff, a time-of-use tariff that rewards shifting usage to off-peak hours could suit you better — especially with a battery. See our roundup of the best energy tariffs for solar panel owners in 2026.
When might your new-build solar not be worth much?
Being honest: if the system isn't MCS-certified and the developer won't resolve it, your options are limited. You can still use the electricity you generate for free — that value remains — but you can't access SEG payments, and some future buyers' solicitors may flag the absence of certification. It's worth pushing hard on this during your snagging period.
Similarly, if your household is rarely home during daylight hours and you have no battery, a significant portion of your generation may be exported at low SEG rates rather than offsetting your own bills. That doesn't make the panels worthless — far from it — but it does mean the case for adding storage is stronger.
If you want to understand how your system compares to what others pay for solar, or you're thinking about adding panels or a battery, get free, no-obligation quotes from vetted local MCS-certified installers through FairSolar. It costs nothing, there's no obligation, and you'll have a clear benchmark to work from.
Frequently asked questions
My new build came with solar panels — do I need to do anything to start benefiting?
Yes — you need to register for Smart Export Guarantee (SEG) payments to get paid for surplus electricity you send to the grid. You'll need your MCS Installation Certificate (from the developer's handover pack), a SMETS2 smart meter, and an application to a licensed SEG supplier. The panels will be generating from day one, but SEG payments only start from when you register, so don't leave it too long.
How do I check if my new build solar panels are MCS-certified?
Check your developer handover pack for an MCS Installation Certificate. You can also search the MCS Installations Database at certificate.microgenerationcertification.org using your address. If nothing comes up, contact the developer — they should be able to provide the certificate or confirm which installer fitted the system.
Can I add a battery to the solar panels on my new build?
In most cases, yes. A retrofit battery can be added to almost any existing solar system using an AC-coupled setup. Until 31 March 2027, adding a battery to an existing home solar system qualifies for 0% VAT — so it's worth acting before that deadline if you're considering it.
Do I have to use the same energy supplier for SEG as for my electricity?
No. As Ofgem confirms, you can choose any SEG-licensed supplier to receive your export payments — it doesn't have to be your current electricity or gas supplier. It's worth comparing SEG tariff rates before you apply, as rates vary significantly between suppliers.
My new build solar system isn't MCS-certified — what can I do?
Raise it with the developer in writing, ideally before your snagging period closes. If the installer who fitted the panels is MCS-certified, the certificate may simply have been mislaid. If the installer wasn't MCS-certified, it's harder to resolve retrospectively and becomes a dispute with the developer. Without MCS certification, you can still use the solar electricity for free, but you cannot register for SEG export payments.