Buying a new build: what to ask about the solar

Start with the dates, not the panels

A new home is not automatically built to the Future Homes Standard just because you are buying it after March 2027. Transitional arrangements protect work whose building control application was submitted before 24 March 2027, provided it commenced before 24 March 2028 — see the timeline.

So the first question is administrative, and the sales office can answer it: when was the building control application for this plot submitted, and when did work commence?

On a large site, plots released in different phases can sit on different sides of that line. Two houses on the same estate, finished the same month, may have entirely different solar provision, and both are lawful.

What “compliant” actually guarantees

Less than most buyers assume, and it is better to know that going in.

The requirement is an output target, benchmarked against a notional array on a south-east to south-west roof at 45 degrees, unshaded — the arithmetic is on the 40% rule page. It says nothing about:

• your electricity consumption, or when you use it
• whether a battery is fitted, or whether the house is wired for one
• whether the array is on the best roof plane rather than the cheapest
• the quality of the panels or the inverter
• whether you can export, or at what price

That last one deserves emphasis. The government’s own impact assessment concedes there “may be some new build sites where solar export to the grid is not possible with current infrastructure”, in which case affected households “would only realise partial or no benefits from solar export”. It expects the incidence to be low. It is still a question worth asking on a large new site.

The documents to ask for

Ask for these before exchange, and treat any reluctance as information:

The BREL report is the one to insist on, because it is the document that would record a shortfall, and it exists whether or not anyone offers it to you.

Ownership, and the question that costs money later

On the overwhelming majority of new builds the panels come with the house. But “usually” is not “always”, and the consequences of the exception are severe enough to be worth one written question:

Is there any lease, licence or other third-party interest over the roof or the installation?

If there is, it appears on the registered title, and it is the same structural problem as a rent-a-roof lease — a legal interest over part of your roof that your lender has views about. Better found now than at week six of your next sale.

Ask your conveyancer to confirm the position on the title rather than relying on the sales office.

What to ask about extending it later

The cheapest time to make a house battery-ready or expandable is while it is being built. By the time you move in, it is a retrofit.

• Does the inverter have headroom for additional panels, or is it sized exactly to the array?
• Is there a spare way in the consumer unit, and space for a battery?
• Has cabling or ducting been run to a plausible battery location — garage, loft, utility?
• Are there estate restrictions in the transfer on external alterations? These are common on new estates, and they can bite on adding panels later — see covenants.
• Is there an EV charge point, and is it solar-aware?

Red flags at the sales office

• “It’s all covered by the Future Homes Standard” in answer to a specific question. The standard is an output target; it does not answer ownership, warranties or export.
• No kWp figure available. This is on the specification. Someone knows it.
• The MCS certificate “will follow”. It often does. It also often does not, and after completion your leverage is gone.
• A solar saving quoted with no assumptions. Ask what self-consumption rate and what unit price it assumes. If they cannot say, the number means nothing — the same test we apply to any quote.
• “You can’t add a battery” stated flatly. Sometimes true for good reasons, often not true at all. Ask why.

If the home has no solar

Check the transitional dates first — it may be entirely lawful.

Then treat it as a house without solar, which is not a disaster: you can install a system specified for your usage, on the roof plane you choose, with the battery you want, and claim SEG on an MCS installation of your own. Our buying cluster is written for exactly that.

What you should not do is assume a new build without panels can be brought up to standard by the developer as a goodwill gesture after completion. That conversation goes much better before exchange.