Solar and Battery in a New Build: What to Decide Before the Walls Close

Building a new home? Prepare conduit, switchboard space, and backup circuits before the walls close.

Building a new home means signing off on hundreds of choices, from tapware to tile grout. Most can be changed later, but a handful of electrical decisions can’t; at least not cheaply. Once the plasterboard goes up at the end of rough-in (when wiring is run through the open frame), that window quietly closes.

The good news is that a solar and battery new build doesn’t require buying a battery today. You can make your house a battery-ready new home for a small cost now, then add the battery in two, three, or five years without cutting into finished walls.

Why a New Build Is the Only Time These Decisions Are Cheap

At frame stage, an electrician can run cable or conduit (a protective sleeve that cables pass through) in minutes. After handover, the same job means cutting access holes, fishing cable through insulated cavities, then patching and repainting. Replacing an undersized switchboard can reach four figures on its own.

There’s also a blind spot. Many builders now offer a solar pre-wire, but battery provisions are rarely raised. Most builder electricians think in terms of panels, not storage. If you’re planning an all-electric home, these battery-side gaps are the ones that cost the most to fix later.

Solar Pre-Wire: The Basics Your Builder May Already Offer

A solar pre-wire new build package usually means empty conduit running from the roof space to the switchboard area, ready for panel cabling. When you discuss new build solar conduit, ask for:

• 32mm conduit rather than 29mm, with separate runs for DC and AC cabling where possible
• A draw wire (pull string) inside, so installers can pull cable through quickly
• Capped ends, to keep out dust, insulation, and pests

Roof orientation matters, too. North-facing roofs generate the most power, and east and west still work well. That's usually settled at the design stage. The bigger, less-discussed decisions sit on the battery side.

The Battery-Ready Provisions Most Builders Don’t Raise

Switchboard Spare Capacity

Your switchboard is the panel of circuit breakers that distributes power around the home. Builder-spec boards are often sized for day-one needs, with few spare positions. For switchboard spare capacity in new build, ask for room for solar, a battery, a future EV charger, and a separate backup section. Four space positions is a sensible minimum. If an EV is likely, it’s worth reading about sizing a battery around EV charging early.

A Properly Designed Backup Circuit

This is the most overlooked decision in any new build. During a blackout, a battery only powers the circuits connected to its backup output. A backup circuit new build plan means deciding now which circuits those are and grouping them in their own section of the switchboard. The usual list is the fridge, lighting, NBN modem, garage door motor, and a few power points.

At rough-in, that’s a simple layout choice. After handover, it can mean reworking the board and tracing circuits behind finished walls. Whole-home backup is possible, but it depends on your inverter and your battery capacity. For a realistic picture, see how a battery behaves during a long outage.

Reserve the Battery Location in the Floor Plan

Battery location for new home design is really about claiming space before something else does. The ideal wall, often in the garage near the switchboard, is also where the hot water unit, laundry tub, or shelving tends to land. Once those go in, the battery gets pushed further away, adding cable runs and cost. Mark a reserved battery zone on the plan now, guided by where a home battery can legally go.

Room to Expand

Most modern home batteries are modular. Capacity, measured in kWh, grows as you add modules. Reserve space for the system you might want in five years, not just the one you’d buy on day one, and factor in the clearance a battery system needs.

VoltX Energy home batteries have a scalable, modular design. They’re built to grow with you, and a well-planned zone makes adding capacity safely down the track far simpler.

Three-Phase Supply: Decide Now, Not Later

Most Australian homes run on single-phase power, a single supply line. Three-phase uses three lines and suits heavier loads such as ducted air conditioning or fast EV charging. A three-phase supply new home connection is much cheaper to arrange during construction than a retrofit, which involves network applications and new cabling. Whether it’s worth it depends on whether single-phase or three-phase suits your household.

What’s Worth Doing Now vs What Can Safely Wait

Items in the left column cost little now and a lot later. You can decide the items in the right column once you’re living in the home and know your actual usage.

What to Ask Your Builder About Solar and Battery

Treat what to ask your builder about solar as a battery conversation, too. Take these questions to your electrical selection meeting:

• Is solar and battery pre-wiring a standard inclusion or a paid variation, and can I have that in writing?
• Will you run 32mm conduit with a draw wire from the roof space to the switchboard?
• How many spare positions will the switchboard have?
• Can essential circuits be grouped for future battery backup?
• Can we keep the nominated battery wall clear of hot water units and shelving?
• Is three-phase available at this site, and what does it cost now?
• Can you send dated photos of conduit and cable runs before plasterboard goes up?

Photos matter because site supervisors change and conduit disappears behind walls. It also pays to have a battery specialist review your electrical plan before rough-in. Our advisors at VoltX Energy can review plans with future storage in mind. When the time comes, you’ll also know what to expect on installation day.

Conclusion

The cheapest time to prepare your home for a solar battery is before you close the walls. Conduit, switchboard capacity, a reserved battery zone and a properly designed backup circuit cost little at rough-in and considerably more afterwards.

You don't need to buy the battery now, and you don't need every upgrade. The right mix depends on your household, your budget and your plans for the next few years. The goal is simply to keep your options open, so a short conversation with your builder now can save a costly retrofit later.