Buying a Perth home that already has solar: what to check before you settle

Perth has one of the highest solar penetration rates in the world — more than 40% of eligible properties now have rooftop solar. When you buy a home with an existing system, you're inheriting everything that came with it: the tariff the system is registered on, the inverter's remaining life, any outstanding connection or compliance issues, and whatever export limit the network has applied.

Some inherited solar systems are assets worth thousands of dollars. Others are liabilities that will cost money to fix or replace within a few years.

Step 1: Find out what tariff the system is registered on

This is the most financially significant question. Three possibilities:

REBS (Renewable Energy Buyback Scheme): Closed to new entrants in 2014. If the system was installed before July 2020 and the seller enrolled in REBS, it pays a flat 7.135c/kWh for all exported electricity. This tariff is rare, valuable for export-heavy households, and non-transferable.

DEBS (Distributed Energy Buyback Scheme): 10c/kWh for peak exports (3pm–9pm), 2c/kWh for off-peak exports. This is the current scheme and does transfer with ownership — the new owner simply continues receiving DEBS credits on their Synergy account.

Not enrolled in any buyback scheme: The system may be generating but exporting for zero payment, or the previous owner may not have completed the Synergy DEBS enrolment process. Worth fixing before settlement.

How to check: Ask the vendor for their Synergy account statements showing DEBS credits, or ask their solar installer which scheme they're on. REBS credit lines appear distinctly on Synergy bills.

The REBS transfer issue: REBS is NOT transferable to a new owner. If the property is on REBS and you buy it, your account will be placed on DEBS instead. You cannot retain REBS when you take over the property. This changes the financial calculation — if the system was optimised for REBS (export-heavy, no battery), the new economics under DEBS may be different.

Step 2: Assess the inverter age and condition

Solar panels commonly last 25–30 years. Inverters typically last 10–15 years. In a system installed in 2012 or 2013 (common in the first WA solar boom), the inverter may be approaching end-of-life.

Typical inverter costs:

• 5kW string inverter replacement: $1,500–$3,000 (installed)
• 10kW three-phase inverter: $2,500–$4,000 (installed)

What to ask:

• When was the inverter installed? (Panels and inverters don't always share the same age — inverters are sometimes replaced mid-life)
• What brand and model is it?
• Is the inverter warranty still active, and who is the WA warranty agent?

How to check in the field: The inverter should have a label showing manufacture year and model. A competent solar inspector can pull this detail during inspection.

Step 3: Check the system size against the current export limit

Systems installed before export limits were introduced (commonly pre-2018 in many Perth suburbs) were often approved with no cap or higher caps. Some older systems in constrained suburbs had their export limits retrospectively adjusted.

More commonly, you may be buying a system that was installed with a fixed 5kW inverter export cap but the household now has an EV or battery planned — which may require a new Western Power application to increase.

What to establish:

• What is the current network-approved export limit?
• If the system has 6.6kW of panels on a 5kW inverter, is there any overpanelling headroom left?
• Can the export limit be increased if needed?

Western Power's connection approval letter is the authoritative source. If the vendor can't provide this, the system's network connection status should be verified via a solicitor enquiry to Western Power.

Step 4: Panel condition and output monitoring

A functioning monitoring platform (Fronius Solar.web, SolarEdge monitoring, Sungrow iSolarCloud, or the Tesla app for Powerwall) lets you see historical generation data. Ask for access to the monitoring account, or request the installer pull the last 12 months of generation data.

What to look for:

• Does generation match expectations for the system size in Perth? (A 6.6kW system should generate approximately 9,000–10,500 kWh/year)
• Are there any panels showing zero or very low output (indicating a failed panel or disconnected string)?
• Are there error codes in the inverter history (indicating past faults)?

Without monitoring: An electricity company report showing quarterly generation from the smart meter is an alternative. Synergy can provide this history if the meter is a smart meter.

Step 5: Physical inspection

A qualified solar inspector (look for CEC accreditation) can conduct a solar-specific inspection covering:

• Panel condition: delamination, micro-cracks (visible under UV light), discolouration
• DC isolator condition (known failure point, especially older red-button isolators — recalled and frequently replaced but some remain)
• Roof penetration seals and weatherproofing
• Wiring condition in the roof cavity and at the inverter
• Inverter condition, operating temperature, error log

Solar inspection cost in Perth: approximately $200–$400. For a system worth $8,000–$12,000, this is reasonable due diligence.

Step 6: Outstanding compliance or connection issues

Some systems were installed under one network approval and later modified (additional panels added, inverter swapped) without updated Western Power approval. This can affect compliance and insurance.

Ask:

• Has the system been modified since the original Western Power approval?
• Are all CEC certificates and compliance documentation available?

Summary: quick checklist before settlement

• [ ] Confirm which export tariff (REBS or DEBS) and understand transfer implications
• [ ] Establish inverter age and remaining warranty
• [ ] Request monitoring data or last 12 months of generation history
• [ ] Obtain Western Power connection approval letter
• [ ] Commission a solar inspection if system is over 7 years old
• [ ] Confirm no outstanding modification or compliance issues

REBS and DEBS tariff rules from Synergy's published tariff schedule. Export limit information from Western Power's residential solar connection policy. Solar inspection costs are indicative Perth market rates as of June 2026.