What only new construction lets you do
Three things become easy during the build and expensive or impossible afterwards.
- Conduit inside the walls. A retrofit usually means surface conduit down an exterior wall. During construction it disappears into the structure.
- A service panel sized for the future. Solar, a battery and an EV charger all want capacity. Specifying a larger panel now costs a fraction of upgrading later.
- Roof design that suits an array. Plane orientation, minimising vent penetrations on the solar plane, and keeping obstructions off it. This is a conversation with the architect, not the installer.
Builder package or your own installer
Builders frequently offer solar as an option or include it as standard, and the quality ranges from genuinely good to a minimum-compliance box-tick.
The questions are the same ones you would ask anyone: which panel and inverter by model, what size system, what is the price separated from the rest of the build, and who holds the workmanship warranty — the builder, or a subcontractor who may not be around.
Get one independent quote for the same house. You may still take the builder package, but you will know what you are paying for the convenience.
The financing advantage people miss
Solar included in the purchase price is financed with the mortgage, at mortgage rates, over the mortgage term.
A solar loan on an existing home is typically shorter and dearer, and frequently carries a dealer fee built into the principal that is not shown separately. Our dealer fee calculator shows what that does to an advertised rate.
This genuinely favours doing it at purchase — provided the system itself is specified properly and not marked up beyond the saving.
Where solar is mandated
Some jurisdictions require solar on qualifying new residential construction. Where such a requirement applies, the system is part of the build rather than an option.
That does not mean it is beyond scrutiny. A mandated system is often sized to the minimum the code requires, which may be well below what your household will actually use. Ask what size is being installed and what it is sized against, and whether upsizing now is possible.
Requirements change, so confirm the current position for your jurisdiction rather than relying on what was true when the development was planned.
How the work runs
- Raise it at design stageRoof orientation, plane size and keeping vents off the solar plane are architect decisions.
- Specify the electrical serviceSized for solar, storage and EV charging together, not just for the house.
- Rough-in conduitRoof to service panel, and to the garage if a charger is remotely likely.
- Compare the packageBuilder price against one independent quote for the same specification.
- Settle the warranty questionWho honours workmanship, and what happens if the subcontractor is gone.
- Install before or at completionWhile scaffolding and roof access are still straightforward.
- InterconnectUsually alongside the main service connection, which can be quicker than a retrofit application.
What moves the price
We do not publish a national average and present it as your price. These are the variables that separate two quotes for the same job — run your own numbers with the cost guides and calculators, and check what incentives you actually qualify for.
| Factor | Why it moves the number |
|---|---|
| Builder markup | The largest and least visible variable. Compare against an independent quote for the same system. |
| Equipment specification | Minimum-compliance equipment costs less and performs like it. |
| System size | A mandated minimum may be well below your actual consumption. |
| Service panel sizing | Cheap now, expensive later. Specify generously. |
| Conduit rough-in | Nearly free during framing; a visible retrofit afterwards. |
| Storage readiness | Space, clearance and circuit provision for a battery even if you are not buying one yet. |
What to ask before you commit
Take this list to the conversation. A professional who answers these directly is telling you a lot; one who deflects is telling you more.
- What is the price of the solar separated from the rest of the build?
- Which panel and which inverter, by model number?
- What is the system sized against — my expected usage, or the code minimum?
- Who holds the workmanship warranty, and for how long?
- Is the service panel sized for a battery and an EV charger as well?
- Is conduit being roughed in to the roof and the garage?
Common questions
Is it cheaper to install solar during construction?
Usually, yes. Roof access is already established, conduit runs inside the walls rather than on them, and the electrical service can be sized correctly from the start. The saving can be offset if the builder marks the package up heavily, which is why an independent comparison quote is worth getting.
Should I take the builder’s solar package?
Sometimes. Ask for the solar price separated from the build, the specific panel and inverter models, the system size and what it was sized against, and who honours the workmanship warranty. Then compare against one independent quote.
Is solar required on new homes?
Some jurisdictions require it on qualifying new residential construction and many do not. Requirements change, so confirm the current position for your specific location rather than relying on general reporting.
Is it better to finance solar in the mortgage?
Financially it usually compares well, because mortgage rates and terms are typically better than solar loans, which often carry a dealer fee inside the principal. That assumes the system is properly specified and not marked up beyond the financing saving.