Solar on older Perth homes: what to know before you install

Perth has a large stock of homes built between the 1950s and 1980s — brick veneer, double brick, or fibro/asbestos cement construction, often with hip roofs, old wiring, and pre-RCD switchboards. These homes are perfectly good candidates for solar, but they come with specific considerations that affect what you'll pay and what your installer needs to assess.

Switchboard compatibility

The most common extra cost for older Perth homes is switchboard replacement or upgrade.

What a standard modern switchboard needs for solar:

• Residual Current Devices (RCDs): required under current WA wiring rules. Older homes may have ceramic fuses or early-generation circuit breakers without RCD protection.
• Available space for the solar production meter and additional circuit protection
• Main switch rated for the additional generation current from the inverter

Cost of switchboard upgrade: $1,000–$3,500 depending on condition and required work. In some cases, a full switchboard replacement ($2,000–$4,500) is the only code-compliant option.

What your installer should check:

• Presence and rating of existing RCDs/MCBs
• Main switch ampacity relative to the intended solar system's inverter output
• Available space in the existing board
• Earth continuity (older homes sometimes have incomplete or corroded earthing)

Important: Solar installers must bring solar-connected circuits into compliance with current wiring rules. An installer who quotes solar without inspecting the switchboard should be asked directly how they plan to handle potential board issues.

Roof access and structure

Hip roofs: Many pre-1980 Perth suburban homes have hip roofs — roofs that slope on all four sides rather than the standard gabled two-slope design. Hip roofs typically provide less north-facing roof area than gabled roofs, reducing panel count. An east/west panel split across two hip roof faces is often the practical solution — fewer panels but distributed generation across morning and afternoon.

Roof pitch: Older Perth homes often have steeper roof pitches (25–35°) than contemporary homes (15–22°). Steeper roofs require safety equipment and take longer to install on — expect a modest price premium. Perth's north-facing roof at 25–30° is actually close to optimal for solar generation, so there's no performance penalty.

Roof material age: Older terracotta tile roofs may have become brittle with age. Walking on old terracotta without breaking tiles requires care. Good installers use tile hooks that distribute weight — but very old or cracked tiles may need partial re-tiling before installation. A reputable installer should assess roof condition during the quote.

Asbestos cement (fibro) considerations

Perth has significant fibro construction from the 1950s and 1960s, including many fibro homes in inner and outer suburbs. Fibro walls are not a solar concern. Fibro roof sheeting is.

Is your roof fibro? Check the roof sheeting material. Corrugated fibro cement sheets are distinctly different from corrugated colorbond iron — the colour tends to be grey-green and the surface rougher. Homes built before approximately 1985 with corrugated roof cladding may have fibro.

What can and can't be done on fibro roofs:

• Drilling into fibro sheeting to mount solar racks is not permitted under WA WorkSafe rules because drilling releases asbestos fibres
• Solar panels cannot be mounted directly to fibro roof sheets using penetrating fixings
• Options: freestanding solar carport/pergola on the property, or roof replacement with metal sheet before solar installation

Roof replacement cost: Fibro roof removal and replacement with colorbond: $15,000–$40,000 depending on roof area. This makes solar-before-roof-replacement the correct order of operations — install solar after the re-roofing, not before.

Note: fibro that is in good condition and unbroken poses minimal risk. Drilling or disturbing it does. If you're unsure whether your roof contains asbestos, commission an asbestos inspector before proceeding.

Wiring and metering

Old wiring: Homes built before 1965 may have rubber-insulated wiring that has degraded over time. This doesn't directly prevent solar installation — the solar cabling is new — but degraded house wiring may prompt the electrical inspector to require remediation of specific circuits.

Metering: Older homes often still have accumulation meters (spinning disc type) rather than smart meters. Smart meter installation is required for DEBS (solar export credits). Western Power arranges meter upgrades as part of the solar connection process — this is automatically triggered by the connection application, but adds time to the overall connection timeline.

Two-phase vs single-phase supply: Most Perth homes have single-phase supply. A small number of pre-1970 homes have two-phase supply (120V/240V split, non-standard) — this is rare but requires specific investigation during the solar quote.

What to ask your installer upfront

For any home built before 1985, make sure your installer:

1. Inspects the switchboard in person before quoting (not a phone quote only)
2. Identifies whether a switchboard upgrade is included in or excluded from the quote
3. Confirms whether the roof material is asbestos cement before proposing mounting
4. Notes the roof pitch and access requirements in their methodology

A detailed scope from the installer — covering all of the above — protects you from unexpected costs between quote acceptance and installation day.

Asbestos identification should be performed by a licensed asbestos assessor. Switchboard assessment and electrical compliance requirements are determined by the installing electrician and must meet current WA wiring rules. Additional costs vary significantly by property.