Why should solar be planned before construction?

Solar design is easier when the roof, switchboard and electrical routes have not yet been finalised. You can preserve useful roof faces, avoid unnecessary obstructions, choose sensible inverter and battery locations, and allow electrical capacity for future loads without undoing finished work later.

Do not size the system from an old electricity bill that belongs to a different home. Build an expected load profile for the finished house instead.

What changes in Victoria from 1 January 2027?

The Victorian Government says new residential buildings must be built all-electric from 1 January 2027, subject to the published scope and exemptions. New commercial buildings are also brought into the all-electric requirements, while industrial and agricultural buildings are treated differently.

For a new home, that means cooking, hot water, space heating and cooling are increasingly planned around electricity from the beginning. Solar and electrical design therefore need to account for more of the home's total energy use.

Design around the loads the completed home will actually have

  • Heat-pump hot water: a flexible load that can often be scheduled into solar hours or Victoria's midday no-cost window.
  • Induction cooking: efficient, but contributes to evening instantaneous power demand.
  • Electric heating and cooling: can be one of the largest seasonal household loads.
  • EV charging: potentially a very large flexible load and a strong reason to protect roof and electrical capacity.
  • Pool equipment: pumps and heating can add substantial, often shiftable demand.
  • Battery storage: changes the value of extra solar and may require dedicated equipment and switchboard planning.

Separate annual energy in kWh from simultaneous power in kW. The first helps size generation and storage. The second matters for inverter, battery output, switchboard and supply decisions.

Design the roof with solar in mind

Before roof penetrations and services are fixed, identify the roof faces most useful for solar and avoid unnecessarily fragmenting them with vents, aerials or plant where practical and compliant.

Orientation is not simply north versus everything else. East and west arrays can spread generation into morning and afternoon, which may suit an all-electric household's consumption profile. The best layout depends on shade, roof geometry, tariff and expected loads.

Allow enough clear area for the system you expect to need in five or ten years, not only the minimum array that suits the home on handover day.

Should a new all-electric home use three-phase power?

Three-phase supply is not automatically required for every new all-electric home, but it is worth discussing early when the design includes larger solar inverters, high-power EV charging, large heating or cooling loads, a pool, workshop equipment or future expansion.

The useful question is not whether three-phase is “better”. It is whether the expected simultaneous loads and proposed solar, battery and EV equipment justify the extra capacity and design flexibility.

Make sure the switchboard has appropriate capacity and spare space for the planned system and likely future additions.

Read the single-phase versus three-phase guide ↗

Choose inverter, battery and cable locations before walls and landscaping are finished

A practical inverter location needs suitable ventilation, weather protection and access. A future battery also has siting and clearance requirements that can make some apparently convenient walls unsuitable.

Coordinate conduit and cable routes while the building is open. Consider roof-to-switchboard pathways, inverter communications, consumption monitoring, EV-charger cabling and a future battery connection.

Pre-wiring does not mean buying every product now. It means avoiding unnecessary demolition or exposed retrofitted cable routes later.

Should the new home include a battery from day one?

Not automatically. A battery should be sized against expected evening demand, solar generation, tariff opportunities, backup requirements and future loads.

Even if the battery is deferred, decide where one could safely go, how it would connect and which circuits you may want backed up. Those decisions are easier before the main switchboard and final electrical layout are complete.

Victoria's Midday Power Saver also means eligible households can access up to 24 kWh of no-cost grid electricity between 11 am and 2 pm. That can influence future battery charging strategy, but the outside-window tariff still matters.

Work through battery sizing ↗

Plan EV charging as part of the home energy system

Decide where vehicles will park, the likely charger location and whether you expect one EV or multiple vehicles. A dedicated cable route and switchboard allowance can be inexpensive during construction and awkward later.

An EV does not necessarily require a home battery. It is often better treated as a flexible load that can charge directly from solar, overnight off-peak electricity or the Midday Power Saver when the vehicle is home during that period.

New all-electric home solar checklist

  • List expected electric appliances and major loads before sizing solar.
  • Estimate EV charging and pool loads separately.
  • Protect useful roof area and coordinate roof penetrations.
  • Discuss single-phase versus three-phase supply with the electrical designer.
  • Allow switchboard space for solar, battery and EV equipment.
  • Choose practical inverter and future battery locations.
  • Plan conduit and cable routes before walls are closed.
  • Check the actual DNSP connection and export arrangement for the property.
  • Revisit system sizing after occupation using real smart-meter data.

Build the expected household before the first bill exists.

Use the household builder to map future appliances, then take that profile into the solar and battery calculator.

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Sources and further reading

Editorial references checked: 5 October 2026

Source labels identify who published each reference, not an independent endorsement. Confirm current requirements and exact product terms before purchasing.