Solar panels on a new build
More new homes than ever arrive with solar already on the roof, and the trend is only going one way as building rules tighten toward low-carbon homes. That sounds like the problem is solved, but a developer-fitted array is not always what you'd choose yourself. Whether you're buying a finished new build or having one built, a few checks make the difference between a token gesture and a system that genuinely pays. Here's what to look for.
Why new builds increasingly have solar
Building regulations have been pushing new homes toward lower carbon, and the Future Homes Standard is set to require new-build homes in England to be highly energy efficient and low-carbon, which in practice means many will include solar as standard. The upshot: if you're buying new, panels may already be part of the package rather than an upgrade you choose.
The catch: developer systems are often small
To meet a regulation at lowest cost, a developer may fit the smallest system that ticks the box, sometimes just 1 to 2 kWp, a handful of panels. That's better than nothing, but it can leave a lot of suitable roof empty and generate far less than the roof could. Knowing the rule-of-thumb output helps you judge it: a system makes roughly 900 to 1,050 units a year per kWp, as set out in how much electricity do solar panels generate. A 1.5 kWp token system makes a fraction of what a typical 4 kWp array would.
What to check on a finished new build
| Check | Why it matters |
|---|---|
| System size (kWp) | Tells you the real output; small systems may be worth expanding |
| Ownership | Confirm the panels are yours, not on a roof lease |
| MCS certificate | Needed to claim export payments; the proof it was done to standard |
| Registered for export (SEG) | So you're actually paid for what you send back |
| Monitoring set up | So you can see it's working and spot faults |
| Warranties handed over | Panel, inverter and workmanship cover transferred to you |
Missing paperwork is the most common new-build issue: the system exists but the MCS certificate, SEG registration or warranties never make it to the buyer. Insist on the full pack, the same one that matters in what is MCS certification.
If you're having a home built
Specifying solar during a self-build or custom build is the cheapest time to do it well. The scaffolding is already up, the roof is accessible, and you can choose orientation and a sensibly sized array rather than a minimum one. You can also design the roof around the panels, avoiding the shading and layout compromises covered in is my roof suitable for solar. Done at build stage, solar is integrated rather than retrofitted.
Can you expand a small new-build system?
Often, yes. If the developer fitted a token array and you have spare south, east or west roof, an MCS installer can usually add panels later, though it's more expensive than doing it all at once because of separate scaffolding and call-out costs. If you suspect your new home's system is undersized, get a quote for expansion and weigh it the way how to read a solar quote describes.
The detail most people miss
A new-build system being small doesn't mean solar "isn't worth it" for your home; it means the developer optimised for compliance, not your bills. The roof, the 0% VAT and the export tariff are all still in your favour. Treat a token array as a starting point you can build on, not the final answer, and judge the full potential of the roof rather than the minimum that was fitted.
Frequently asked questions
Increasingly yes, as building rules push new homes toward low carbon. Many now include solar as standard, though often a small system sized to meet the regulation.
The kit is usually fine, but developer systems are often small, so they generate less than the roof could. Check the system size and consider expanding if there's spare roof.
Usually, if you have suitable spare roof. An MCS installer can extend the system later, though adding panels separately costs more than doing it all at once.
A set of building standards intended to make new homes in England highly energy efficient and low-carbon, which in practice means many new builds will include solar.