Got an Old Solar System? Your Upgrade Options in 2026

Drive through Toowoomba, Dalby, Warwick or Pittsworth and you'll spot them on roof after roof: small solar systems installed between 2009 and 2015, back when 1.5kW to 5kW was considered a big setup. A lot of those systems have done a perfect job. But after 10 to 15 years in Queensland sun degradation can start to creep in and this causes many systems to slow down, un-rectified fault codes pop up, or simply the system is now too small for how the household uses power today.

If that sounds like your roof, you've got four main options. Here's an honest look at each one, what it costs you, and which situation it suits.

Signs Your Old System Needs Attention

Before deciding anything, it's worth knowing what's actually going on. Common signs include:

• Your inverter shows a red light, an error code, or a blank screen

• Your power bills have crept up even though your usage hasn't changed

• Generation on clear days is noticeably lower than it used to be

• Panels show visible damage or dirt buldup, cracks, browning, delamination, or corroded frames

• Your household has grown, added air conditioning, a pool, or an EV, and the system no longer keeps up

A dead inverter is the most common issue. Most string inverters are designed to last around 10 to 15 years, so if yours is original to a 2010–2013 install, it's living on borrowed time. Panels usually outlast inverters by a long way, but older panels lose a little output every year.

Option 1: Replace a Dying Inverter If your panels are in good condition and the system size still suits you, replacing just the inverter is usually the cheapest fix. It gets your system generating again without starting from scratch.

This option suits you if:

• Your panels are undamaged and still producing reasonably well (above 80%)

• You're on the 44c feed-in tariff and want to keep it (more on this below)

• You're happy with your current system size (it's covering your current usage)

One thing to consider: if you're not on the 44c tariff and you think you'll want a battery in the next few years, replacing the old inverter with a hybrid inverter now can save you money later. You fix today's problem and become battery-ready at the same time.

Option 2: Add More Panels Adding panels sounds simple, but on older systems it's often trickier than people expect. Panels from 2011 might be 190–250 watts each; today's panels are well over 440 watts. Mixing old and new panels on the same string can drag the whole string down to the level of the weakest panel.

There are two ways to do it:

• Top up to your inverter's limit: if your inverter has spare capacity, extra panels can be added to bring the array up to the inverter's rating

• Add a second, separate system: a new set of panels with its own modern inverter, running alongside the old one

A second system gives you far more flexibility and the new panels can qualify for the federal STC rebate. However, both options need network approval from Energex or Ergon, and export limits on your connection can affect how big you can go. If you're on the 44c tariff, adding a second system will cost you that tariff so this option generally makes the most sense for customers on standard feed-in rates.

Option 3: Add a Battery

For households on standard feed-in tariffs, a battery is often the upgrade that delivers the biggest change to your power bill. In regional Queensland, the Ergon feed-in tariff dropped to 6.006 cents per kWh from 1 July 2026, down from 8.66c the year before. Exporting your solar earns very little; storing it and using it at night saves you the full grid price instead.

The catch with old systems is that most original inverters can't talk to a battery. You have two paths:

• AC-coupled battery: a battery with its own built-in inverter, added alongside your existing system. Good if your old inverter is still healthy. We recommend Goodwe ESA modular batteries and the Sigenergy batteries with their built-in inverter.

• Hybrid inverter + battery: replace the old inverter with a hybrid unit that manages both panels and battery. Good if your inverter is dying anyway and this can be a little cheaper then the all in one battery modules.

The federal Cheaper Home Batteries Program still applies to batteries added to existing solar. For installations from May to December 2026, the rebate works out to roughly $250 per kWh of usable capacity, so around $2,500 off a typical 10kWh battery. The full rate applies to the first 14kWh, with reduced rates above that. The rebate steps down again on 1 January 2027, so if you're seriously considering a battery, installing before the end of the year locks in the current rate.

One small old system paired with a battery won't always be enough to fill it each day, especially in winter. Often the best result comes from combining a battery with Option 2 or Option 4.

Option 4: Full System Replacement

Sometimes the honest answer is that the old system has had a good innings. A full replacement makes sense when:

• Panels are damaged, heavily degraded, or from a manufacturer that no longer exists

• Your system is 1.5–3kW and your household now uses far more power

• You're not on the 44c tariff, so there's nothing to protect

• You want a battery-ready hybrid system built properly from day one

A modern 6.6kW to 10kW system with quality panels and a GoodWe inverter will typically generate two to four times what an old 1.5–3kW system produces, on the same roof space or less. New systems qualify for the federal STC rebate, applied as an upfront discount, although the STC rebate also reduces every 6 months until the scheme ends in 2030.

We remove and dispose of the old equipment as part of the job, so you're not left with panels stacked in the shed.

Protecting Your 44c Tariff Before It Ends in 2028

If your system was installed before July 2012, you may still be on the Queensland Solar Bonus Scheme's 44 cents per kWh feed-in tariff. That's roughly seven times the current regional rate, and it runs until the scheme ends on 30 June 2028.

Under the Queensland Government and Energex/Ergon rules, you can generally:

• Replace your inverter with one of the same or smaller capacity

• Replace faulty components with like-for-like parts

• Add panels only up to the rated capacity of your existing inverter

You will lose the 44c tariff if you:

• Install a larger inverter

• Add panels that take your array above your inverter's rated capacity (Energex and Ergon allow only a small tolerance on panel replacements)

• Add a battery that can discharge while your solar is generating, or export to the grid

• Add a second generating system that runs at the same time as your 44c system

• Add someone other than your spouse to the electricity account

Once the 44c tariff is removed, it doesn't come back. So for most 44c customers, the smart move is to keep the system running with like-for-like repairs until mid-2028, then plan a bigger upgrade, new panels, a hybrid inverter and a battery, once the tariff ends. If your system dies completely before then, it's worth running the numbers: a dead 44c system earns nothing, and a full replacement might come out ahead.

Which Upgrade Is Right for You?

Why Talk to a Local Installer First

Upgrading an old system isn't one-size-fits-all. The right answer depends on your tariff, your inverter's approved capacity, your roof space, your network connection, and how your household uses power. Get it wrong on a 44c system, and you can lose thousands of dollars in feed-in credits overnight.

We're based in Toowoomba and work on older systems across the Darling Downs and regional Queensland every week. We'll check your current setup, look at your bills, confirm your tariff status, and give you an honest recommendation even if that recommendation is to leave it alone for now.

📞 Got an old system that's slowing down? Call William on 0424 030 189 or visit www.qldoutbacksolar.com for a free, no-pressure system check.

 References & Further Reading

Government rebate details and tariff rates change regularly. We recommend checking these sources for the latest information.

1. Queensland Government: Solar Bonus Scheme 44c feed-in tariff https://www.qld.gov.au/housing/home-energy-savings/solar-bonus-scheme Official rules on what you can and can't change without losing the 44c tariff.

2. Energex: Solar feed-in tariff changes https://www.energex.com.au/contractors/solar-installers/solar-feed-in-tariff-changes Conditions under which the 44c tariff is removed in South East Queensland, including panel replacement tolerances.

3. Ergon Energy: Solar feed-in tariff changes https://www.ergon.com.au/network/contractors/solar-installers/solar-feed-in-tariff-changes The equivalent rules for regional Queensland customers on the Ergon network.

4. Queensland Competition Authority: Regional solar feed-in tariff 2026–27 https://www.qca.org.au/project/customers/solar-feed-in-tariffs/regional-queensland-feed-in-tariff-2026-27/ Official source for the 6.006c/kWh Ergon network feed-in tariff, effective 1 July 2026.

5. Federal Government: Cheaper Home Batteries Program https://www.dcceew.gov.au/energy/programs/cheaper-home-batteries Official details on the battery rebate, eligibility, tiers and scheduled reductions.

6. Clean Energy Regulator: Small-scale Technology Certificates https://www.cleanenergyregulator.gov.au/RET/Scheme-participants-and-industry/Agents-and-installers/Small-scale-technology-certificates How the STC rebate works for new panels and replacement systems.