Solar panel upgrades in Melbourne: extend or replace your old system

Before you upgrade: what have you got?

Four things decide which upgrade fits, and you can find most of them from the ground:

1. The inverter and panels. Photograph the inverter’s label for its brand and model; the app or your invoice names the panels. Finding your make and model.
2. The install year. Your electricity distributor (ask for the connection date) or Energy Safe Victoria (a Historical Certificate of Electrical Safety) can tell you.
3. What it makes now. PVGIS models about 164 kWh in January and 65 kWh in June for each kW of north-facing panels in Melbourne: compare your app’s figures for the same month. Is it underperforming?
4. The condition of the panels and wiring. Cracks, an ageing DC isolator or a wiring fault need an electrician’s inspection. What an inspection checks.

Upgrade, extend or replace: which fits your old system?

Start with what the system makes now: compare a month in your monitoring app or bills with the same month when it was new. Panels wear slowly, so a big drop points to a fault; a working system that no longer covers your use needs more panels.

Age matters most for the inverter. Solar Victoria’s buyers guide says households who add panels often find that changed standards mean a new inverter anyway.

How long solar panels last

Old 1 to 2 kW systems: keep, extend or replace?

In Melbourne a 1.5 kW system makes about 2,129 kWh a year (PVGIS model, north-facing), against about 9,319 kWh for a 6.6 kW system on a 5 kW inverter. If the original inverter is still running, it may be past the 10 to 15 years Solar Victoria expects an inverter to last, and that usually decides it:

• Keep it while the inverter works, and add a second system beside it when you need more power.
• Extend it with a new inverter that runs the old panels and the new ones: STCs are paid on the new panels only.
• Replace it when the panels are damaged or the inverter has failed. A whole new system earns STCs again, and Solar Victoria says a system 10 or more years old might qualify for its panel rebate.

Was yours on the premium feed-in tariff? It ended on 1 November 2024, so an upgrade no longer loses it: the old premium tariff.

Adding panels: inverter capacity and matching panels

The inverter sets the limit. Under the SAA Technical Requirements (version 1.9, February 2026), a system without a battery needs an inverter rated at least 75% of the panels’ peak power, within the maker’s own maximum: a 3 kW inverter runs up to 4 kW of panels, a 5 kW one up to 6.67 kW. Solar Victoria tells households to check this before accepting a quote. With no room left, a new inverter runs the old and new panels, or a second inverter runs the new ones as a separate system.

Melbourne’s distributors pre-approve up to 10 kW of inverter on a single phase home and 30 kW on three phase, counting solar and battery inverters together, so a second inverter adds to the first: single or three phase.

Matching new panels to old ones

Panels in one string share one current, so mixed old and new panels run at the pace of the weakest; new panels usually go on their own string, ideally a spare tracker (MPPT) input of the inverter. The current ranges on our panels page are 435 to 475 W and take about 2 to 2.1 m² of roof each, so we measure the space left first.

For new panels we fit Canadian Solar, REC, Winaico and Phono Solar, the brands our previous site listed; your quote confirms the model.

The panels we install

Do extensions get STCs? Export approval when you extend

STCs on the new panels

An extension earns STCs on the new panels only; the old panels are not counted again. The Clean Energy Regulator’s rules differ by case. Keeping the existing inverter, the new panels and that inverter must be on the Clean Energy Council’s approved list, the inverter must have room, and every component must meet the current relevant standards. With a new inverter, the installer must re-certify the entire system, including its connection to the home’s wiring, as safe and compliant, and upgrade any part that no longer meets the rules. If your first system’s STC claim is still in progress, wait: expanding before it is approved risks losing every STC for the system.

The STC calculator

Approval from your distributor

AusNet needs pre-approval before installation and sets the export limit from the capacity available when you apply, so it can differ from the old one. CitiPower and Powercor want the pre-approval before you sign, then record the upgraded system and its export limit.

Since 1 October 2024, new, upgraded and replacement systems up to 200 kVA must meet Victoria’s emergency backstop rules, says Solar Victoria: an inverter that can communicate using CSIP-AUS and a connection to the internet. Its installer Q&As count added capacity as an upgrade, and an older inverter may not qualify: one more reason an extension often ends with a new inverter.

A pre-approval can come back with a 0 kW export limit. On United Energy’s network, homes given one have been able to choose flexible exports instead since 1 July 2026: up to the inverter’s limit (at most 10 kW) most of the time, with a CSIP-AUS compliant inverter and an internet connection. CitiPower and Powercor offer the same choice. Whatever the limit, exports earn only your retailer’s rate: the Essential Services Commission has set no minimum feed-in tariff since 1 July 2025.

Export limits on each network

Size the extension to daytime use, a battery or electrification

Because exports earn little and may be capped, size the new panels to what the home will use: more daytime use now, a battery that stores the surplus for the evening, or a planned switch from gas appliances or petrol car to electric. Re-run the solar calculator at the new total size to see how much of the extra output you would use yourself.

Replacing old panels, an old inverter or the whole system

Replacing solar panels

A damaged panel can be swapped for one of a similar size and rating, and one producing well below its performance warranty may be a warranty claim. Keeping the old inverter means no STCs: the Clean Energy Regulator treats it as an update to a system that has already claimed.

Removing and recycling old panels

Replacing the inverter

When an inverter fails, the panels make nothing until it is repaired or replaced. A replacement must meet the backstop rules unless it is like for like on a system approved before 1 October 2024, and a hybrid inverter lets you add a battery later. An inverter alone adds no panels, so it earns no STCs.

For new inverters we fit Sungrow, Fronius and Alpha ESS, the brands our previous site listed; your quote confirms the model.

Inverter repair or replacement

Replacing the whole system

If the panels are damaged, or the system is small and the inverter failing, replacing everything may beat patching it, and a new system earns STCs again. Solar Victoria’s panel rebate is for addresses with no solar installed in the last 10 years, and it says owners of a system 10 or more years old might be eligible to replace or expand it. Your distributor or Energy Safe Victoria can tell you when yours went in.

Solar Victoria’s panel rebate

Upgrading a system another company installed

Most upgrades are to a system someone else put in. Three sets of rules apply before any work starts:

• The old installer’s warranty. Solar Victoria says the installation warranty covers the installer’s own workmanship, not the panels or inverter, and its maintenance guide warns that a warranty could be void if a service isn’t done by the company that installed the system. Ask the old installer in writing what theirs still covers once another company alters the system, and get the new installer’s terms for its own work.
• The makers’ conditions. Sungrow’s inverter warranty excludes unauthorised repairs, and a claim can be refused after replacing the inverter without Sungrow’s prior consent; Canadian Solar’s panel warranty excludes repairs without Canadian Solar’s authorisation, or tampering. Read your own brands’ terms: what voids a warranty.
• The Clean Energy Regulator’s rules. Keeping the existing inverter, every component must meet the current relevant standards. With a new inverter, the new installer must re-certify the entire system, including its connection to the home’s wiring, as safe and compliant: that covers the parts the first company fitted too.

Send us the brands and models, and a photo of the inverter label, when you book, and we’ll confirm what we can do with the system.

Systems installed by another company

The old premium feed-in tariff and upgrades

Victoria’s premium feed-in tariff paid at least 60 c for each kWh exported. It started in late 2009, closed to new applicants at the end of 2011 and was limited to systems of 5 kW, say CitiPower and Powercor. Adding panels made a household ineligible for it, so owners on it had good reason to leave their systems alone.

The scheme ended on 1 November 2024, so there is no premium rate left to lose. Exports now earn your retailer’s own feed-in tariff: Victoria has had no minimum since 1 July 2025 (the last, in 2024–25, was 3.3 c per kWh flat). Extra panels pay mainly through the power you use yourself, in daylight or from a battery.

How feed-in tariffs work now

Adding a battery at the same time

If the inverter is being replaced anyway, a hybrid inverter can run the panels and a battery together; if the old inverter stays, an AC-coupled battery brings its own inverter. Under the SAA rules, a system with a battery may carry more panels than the 75% ratio allows, up to the inverter maker’s limit, so doing both at once can make room for more panels.

The Cheaper Home Batteries Program discount applies to a battery added to existing solar as well as new solar, if it meets the program’s rules, including being able to join a virtual power plant (source: Clean Energy Regulator).

AC vs DC coupled batteries

The battery rebate

How much does a solar upgrade cost?

• Panels alone: about $80 to $300+ each, retail, before installation (Solar Choice Price Index, October 2026, market data).
• A battery for existing solar: 10 kWh with its own inverter averaged $8,284 installed after the rebate, nationally (Solar Choice Battery Price Index, August 2026, market data).

Get an upgrade quote

Solar upgrades: your questions