Solar inverter replacement in Perth: what to expect and what it costs

Your inverter is the part of your solar system most likely to fail first. Panels commonly keep working for 25 to 30 years or more. The inverter, which converts your panels' DC output into the AC power your home uses, wears out well before that. If your Perth system went in between 2010 and 2016, you're either due for an inverter replacement or getting close.

The short version: a like-for-like string inverter swap is the cheapest fix, and it makes sense if your panels are healthy and you have no battery plans. Want a battery within a few years? A hybrid inverter now saves you paying twice. And if you're on the old REBS feed-in tariff, check with Synergy in writing before you change anything, because losing REBS is permanent. The sections below walk through each of these.

How do I know my inverter is failing?

There are four common signals. Any one of them is worth acting on.

It is showing fault codes. Modern inverters display error codes on the screen or in their monitoring app. The ones to watch for:

• Isolation failure: DC wiring insulation has broken down. This is a safety issue, so get it looked at straight away.
• Grid fault: the inverter can no longer sync with the grid frequency.
• Overtemperature: the internal thermal management has failed.
• GFCI trips: the ground fault protection keeps tripping.

If you want to decode what a specific message means before you call anyone, our guide to common solar inverter error codes in Perth covers the frequent ones.

Its output has dropped for no obvious reason. If your monitoring shows generation well below what healthy panels should produce on a clear day, and a clean plus a shade check do not explain the gap, the inverter may be running at partial capacity without flagging a fault.

It is well past its warranty. An inverter running at 12 years or more with no monitoring visibility is a quiet risk. You may not notice it's underperforming until your bill savings slip.

It has stopped completely. No light on the display, no output in the app. That can be a blown fuse, an AC or DC isolator failure, or a failed circuit board inside the inverter.

For the bigger picture on how long these units are built to last and what shortens that, see our solar inverter lifespan guide for Perth.

What are my replacement options?

You have three main paths, and the right one depends on the state of your panels and whether a battery is on your horizon.

Like-for-like string inverter. Replace the failed unit with a current string inverter of the same capacity. This is the most cost-effective route when your panels are in good shape and you have no plans to add battery storage. The string inverter brands commonly sold in WA include Fronius, Sungrow, GoodWe, SolarEdge and SolaX. Inverter prices have come down over the past decade, so a straight swap today is a smaller job than many people expect.

Upgrade to a hybrid inverter. A hybrid inverter is battery-ready: it manages solar, battery and grid in one unit. If you think a battery is likely within the next few years, fitting a hybrid when your string inverter fails positions the system for a battery retrofit later, and it means you're not paying to replace the inverter twice. Adding the battery down the track costs less than a full retrofit would, because the battery-capable inverter is already in place. Our hybrid inverter guide for Perth explains how they work and when a plain string inverter is still the smarter buy.

Switch to microinverters or DC optimisers. If you're replacing the inverter because of shade problems rather than age or failure, that moment can be a good opportunity to move to a microinverter setup, where each panel runs more independently. It's a bigger rework than a straight swap, so expect it to cost more. Our microinverter versus string inverter comparison lays out the trade-offs.

What does an inverter replacement cost in Perth?

There is no single price, and anyone quoting one sight unseen is guessing. What you pay depends on the inverter type and capacity, the brand, your installer, and whether your existing cabling and monitoring gear are compatible with the new unit.

As a rough shape of the market:

1. A like-for-like string inverter swap is the lowest-cost option, since it is the most straightforward job.
2. A hybrid, battery-ready inverter costs more than a like-for-like string swap, because you're buying the extra battery-management capability up front.
3. A microinverter conversion typically costs the most, because it's a larger rework of the system rather than a single-unit swap.

There is also usually a service call and diagnostic fee to identify the fault, which may be separate from the replacement itself. Ask whether it's credited against the job if you go ahead. Get itemised quotes from more than one SAA-accredited installer, and make sure each quote is for the same scope so you're comparing like with like. Figures move with the brand and the site, so treat any number you see online as indicative only and let the quotes in your hand set your expectation.

Will replacing my inverter cancel my REBS feed-in tariff?

If you're on the old Renewable Energy Buyback Scheme, this is the most important thing on the page. REBS pays a flat 7.135 cents per kWh for every unit you export, at any time of day, and it's closed to new customers. The current DEBS tariff pays a higher 10 cents per kWh in the midday window but only 2 cents at all other times, so how the two compare for your household comes down to when your system actually exports. The point is that REBS is a legacy arrangement you can't get back once it's gone, so it's worth protecting.

A like-for-like inverter replacement does not cancel REBS. It's still the same system, and routine maintenance or a straight replacement keeps your REBS intact.

A bigger change might. Adding panels to increase capacity, reconfiguring the system, or in some cases fitting an inverter of a substantially different capacity can trigger a Synergy review of your REBS eligibility.

So the rule is simple: if you're on REBS and you're doing anything beyond a like-for-like swap, confirm it with Synergy in writing first. Losing REBS is permanent, and the higher rate doesn't come back. If you want to understand how the two schemes compare before you make a call, read how DEBS and REBS compare.

Should I add a battery when I replace the inverter?

For a household whose inverter fails after 2020, the decision usually comes down to one question, and it's easiest to walk through in order.

1. Do you want a battery within the next few years? If yes, pay the premium for a hybrid inverter now and add the battery later. You avoid replacing the inverter a second time.
2. No battery on the horizon? Fit a good like-for-like string inverter and keep the cost down.

One caveat if you're on REBS: adding a battery may affect your REBS status, so get explicit written confirmation from Synergy before you connect one to a REBS-enrolled system. If you're weighing the battery question more broadly, our guides on adding a battery to an existing Perth solar system and what "battery-ready" actually means go deeper.

Who should replace my inverter, and what should I ask them?

You have a few options for who does the work:

• Your original installer, if they are still trading.
• The inverter manufacturer's warranty service team, for a failure that is still within warranty.
• An SAA-accredited solar installer, for an out-of-warranty replacement.
• Some electricians who specialise in solar fault diagnosis.

Before you commit, ask each one:

• Is this a like-for-like replacement or an upgrade?
• Will the new inverter still work with my existing monitoring system?
• Will this affect my REBS status, if I am on it?
• What warranty comes with the replacement inverter?
• Do you provide a written service report?

On that warranty question: the New Energy Tech Consumer Code sets a minimum five-year whole-of-system warranty for Approved Sellers, so that is your floor for the installed job. The product warranty on the inverter itself is set by the manufacturer and varies from model to model, so check the specific unit's datasheet rather than assuming. If a battery-ready hybrid is on your shortlist, our hybrid inverter guide is worth a look before you sign.

What should I do after the new inverter is in?

Four quick jobs once the replacement is running:

1. Test the generation. Check the output in the monitoring app within the first 24 hours after a clear day.
2. Compare it to what you should be getting. At Perth's 5 peak sun hours, a 6.6 kW system should produce roughly 26 to 32 kWh on a clear summer day. If your numbers are well short of that, flag it early.
3. Update your Synergy records. If Synergy needs to be told about the inverter change for your REBS or DEBS arrangement, do it promptly.
4. Keep the paperwork. Installation certificate, inverter serial number, and warranty documents, all in one place.

If your solar generation has dropped noticeably compared with a year or so ago, upload your most recent Synergy bill to BillWise. The analysis can tell you whether your consumption has shifted or whether the drop looks like an inverter problem.