Planning solar during a home renovation in Perth: timing, pre-wiring, and coordination

A home renovation — whether a full knockdown-rebuild, major addition, or switchboard upgrade — is an opportunity to set up your home's electrical infrastructure for solar and battery storage at significantly lower cost than a standalone solar installation. Here's what to coordinate and when.

Why a renovation is the best time for solar prep

The two biggest cost components in a solar installation are the equipment (panels, inverter) and the labour (particularly conduit runs and switchboard work). During a renovation:

• Conduit runs are cheap when walls are open. Running conduit from the roof to the switchboard inside an open wall cavity costs $20–$80 for materials and 30 minutes of an electrician's time. The same run in a finished home requires cutting, patching, and repainting — $300–$800 in additional labour.
• Switchboard work is already budgeted. If you're upgrading your switchboard anyway (which most renovations require), the marginal cost of preparing for solar (adding a main switch, space for a solar/battery circuit breaker, earth bar sizing) is minimal.
• Roof access is unobstructed. During a reroofing or roof framing phase, it's easy to install roof penetrations, rafter brackets for flush-mount rails, or roof tiles set aside for conduit exits.

If you're reroofing during a renovation

A reroof is the best opportunity to future-proof for solar:

Have your solar installer assess the roof framing before tiles go on. The solar installer can:

• Identify the best rafter positions for rail attachment (typically 600mm centres, but varies)
• Advise on the roof pitch and orientation for maximum output
• Install roof penetrations (conduit exits, rafter brackets) while the roof is stripped

Request specific actions before reroofing:

1. Install a 25mm conduit from the roof space to the switchboard location (wire pull later)
2. Leave the conduit capped at the roof exit point
3. Have the solar installer review the tile/metal interface for future rail attachment

For metal roofing (Colorbond): Rail attachment on Colorbond uses standing seam clamps or tri-clamp tiles — no penetrations. Easier than tiles.

For concrete/terracotta tile roofing: A roof penetration is standard — typically an aluminium flashing plate around a 40mm conduit. Install this before tiles go on.

Switchboard preparation during a renovation

Even if you're not installing solar immediately, prepare the switchboard for future solar:

Minimum pre-solar switchboard preparation:

• Dual-pole mains switch (required for solar grid connection — single-pole is not acceptable)
• Spare circuit breaker positions (minimum 2 — one for solar inverter, one for battery/EPS circuit if future battery is planned)
• Adequate earth bar capacity (solar adds additional earth bonding requirements)
• Space for a bi-directional meter (if moving from single-direction meter — your switchboard needs space for the meter to be upgraded by Western Power)

Ask your electrician explicitly: "Can you prepare this switchboard for future solar and battery installation?" — it's a standard request and adds minimal cost during a switchboard replacement.

Three-phase vs single-phase: If your renovation involves a significant load increase (large ducted AC, EV charger, large workshop), consider three-phase power supply at this stage. Three-phase solar is available and simply uses a three-phase inverter — but retrofitting from single to three-phase supply later involves Western Power fees ($3,000–$8,000+) that you avoid by doing it now.

Coordinating the solar installer with the builder

Solar installers are a specialised trade — they're typically not managed by your builder as part of the standard construction programme. You need to coordinate them yourself.

Recommended sequence:

1. During design/approvals phase: Get a solar installer to assess your renovation design — roof pitch, orientation, shading from proposed new structures (pergola, second storey, neighbouring buildings)

2. Before roof frame inspection: Have the solar installer attend (or provide specifications to your builder/framing contractor) for rafter placement and roof penetration prep

3. Before internal linings go on: Have your electrician install conduit runs while walls are open. The solar installer should specify conduit size (typically 25mm or 32mm) and route

4. After switchboard installation but before linings: Confirm the switchboard has adequate solar preparation (see above)

5. After practical completion (or as a last trade): Solar installer returns to install panels, inverter, and commission the system. NCN with Western Power takes 5–20 business days — factor this into your handover timeline if you want the system operational at move-in.

What you can defer vs what to do now

Do NOW during renovation (low cost while disruption is already happening):

• Conduit runs (roof to switchboard)
• Switchboard preparation (main switch, spare positions, earth bar)
• Roof penetrations or bracket installation if reroofing
• Three-phase supply upgrade if contemplating large loads

Can defer until after move-in:

• Panel installation
• Inverter installation
• Battery installation (but pre-wire for battery location if you know where it goes)
• NCN approval with Western Power

Pre-wiring for the battery is worth doing if you know the battery location. A 10kWh battery (Sungrow, BYD, Alpha ESS) is typically wall-mounted in the garage or utility room. Pre-wiring a 240V circuit to that location (with conduit space for DC cables from future solar) saves $200–$500 later.

Heritage and planning constraints in Perth

Some Perth suburbs have heritage overlays or built form requirements (particularly in inner suburbs and coastal areas) that affect panel placement. Before your renovation design locks in, check:

• Heritage overlay: If your property is on the State Register or local government heritage list, panels visible from the street may require heritage council approval. Rear or side roof placement is typically accepted without full heritage approval.
• Tree clearing: Mature trees removed during a renovation may be the best time to address future shading — urban tree permits in Perth require landowner application, but trees on your own lot with the landowner's approval are generally permissible to manage.
• Stormwater and drainage: Changes to the roof during renovation may require updated stormwater plans — solar panels affect water runoff patterns.

Renovation + solar: approximate cost difference

Installing solar conduit and switchboard prep during a renovation vs retrofitting later:

| Item | During renovation | Retrofit later | Saving | |---|---|---|---| | Conduit run (roof to switchboard) | $80–$200 | $300–$800 | $220–$600 | | Switchboard main switch + spare positions | $100–$300 | $400–$800 | $300–$500 | | Roof penetration/bracket prep | $100–$250 | $200–$500 | $100–$250 | | Total typical saving | | | $620–$1,350 |

The solar equipment itself (panels, inverter) costs the same whether installed during or after the renovation. The saving is purely in electrical/building work that's cheapest while the house is already open.

The window where renovation disruption is already happening is the cheapest time to prepare your home for solar. Even if you're not ready to commit to panels and an inverter yet, pre-installing conduit and switchboard preparation at renovation time saves $600–$1,350 and avoids patching and repainting finished work later.