If your solar system was installed around 2016, there’s a good chance it’s still switching on every morning. And yet, your electricity bill is still around $800.
This is the quiet problem many households are facing in 2026. A huge wave of solar systems went up 10 years ago, designed for smaller homes, lower energy use, and much cheaper power. Although they haven’t “failed,” they have slowly fallen behind, which can mean some homes are now losing up to 30% of their original output without realising it.
Since the system still works, most owners assume it’s doing its job. However, in reality, many older systems are stuck in a kind of solar limbo — producing just enough to look alive, while quietly costing their owners far more than they should.
Before spending money on repairs, it’s worth asking a more important question: Is your solar system worth fixing at all, or is it time to repower it for how homes actually use energy in 2026?
Why 2016-2017 systems are quietly hitting a wall
Most solar systems installed around 2016 or 2017 were designed for a very different energy reality. Back then, a typical residential install sat between 3kW and 5kW. That was enough to cover daytime usage, offset part of the bill, and take advantage of generous feed-in tariffs (FiTs). Few households were thinking about electrification, EV charging, or running multiple high-load appliances at once.
Fast forward to 2026, and that design no longer lines up with how homes actually use electricity. Energy demand has crept up while grid prices have risen sharply. Air conditioners run longer, home offices are permanent, and more appliances are electric-only. Yet the solar system on the roof is still locked into a decade-old capacity.
At the same time, many of the components in these systems are simply ageing out. Early-generation inverters are often past their original warranty period, panels are operating below their rated output, and monitoring is basic or misleading. The result is a system that hasn’t failed outright, but no longer delivers bill relief.
The invisible 30% problem
Most solar systems don’t fail in a way that’s obvious. They decline slowly, and that’s what makes the problem easy to miss.
Over time, panels lose efficiency due to normal degradation, heat exposure, and general wear. This happens gradually, usually a fraction of a per cent each year. After 10 years, that small annual drop can add up to a 20-30% reduction in output, even though the system still appears to be operating normally.
What makes this harder to spot is how solar performance is usually monitored. A green inverter light only shows that the system is on, not that it’s producing what it should. Monitoring apps show energy being generated and exported, but they rarely show how that compares to the system’s original capacity or to modern performance standards.
Seasonal variation also hides this issue. A cloudy stretch, a mild winter, or a particularly hot summer often gets the blame for weaker results. In reality, the system may simply be producing far less than it did when it was new. The outcome is a slow leak in savings that shows up as electricity bills that stay higher than expected year after year.
How to tell if your solar is becoming a “zombie”
If your system is underperforming, the clues are usually hiding in plain sight. A quick check against the points below can tell you whether your solar is still pulling its weight or just coasting.
- Your bills haven’t improved: Your solar is producing power, but your electricity bill is still stubbornly high or rising year on year, even though your household habits haven’t changed much.
- Current output doesn’t match original estimates: Compare today’s annual generation with the estimate from your original install paperwork. A consistent shortfall can point to degradation rather than weather.
- Your inverter is more than 8-10 years old: Many inverters from 2016 are now out of warranty. Ageing units can limit output or cut in and out without fully failing.
- Monitoring apps show activity, not performance: A green light or moving graph only shows the system is on. It doesn’t tell you whether it’s producing what it should be.
- Your system is 3kW-5kW and still unchanged: Older, smaller systems often can’t keep up with modern household demand, even if every component is technically “working.”
- Seasonal drops feel permanent: If weaker performance never really recovers after summer or winter, it may be degradation rather than short-term conditions.
If several of these sound familiar, the usually usually that the system itself is no longer used to how your home uses energy today.
Repair, replace, or repower? The 2026 reality
If your solar feels like it’s still “alive” but not really saving you money, it might be time to look beyond just repairs — this is also where a professional solar health check can make a huge difference. That’s exactly the kind of service offered by Solar Service Guys – Solar Panel and System Cleaning and Health Checks from Energy Matters, Australia’s dedicated solar servicing experts who focus on inspecting, cleaning and maintaining systems so they perform as they should.
When an older solar system underperforms, the instinct is often to fix what’s there. Swap a panel, replace the inverter, patch the weakest link and hope the savings return. In 2026, that approach often delivers far less value than homeowners expect.
Repairs on older systems can be surprisingly expensive once labour, compliance, and compatibility are factored in. New inverters don’t always play nicely with ageing panels. Replacing individual panels rarely restores lost efficiency across the whole array. In many cases, you’re spending money to keep a system running at a level that was already undersized when it was new.
Replacement sounds more decisive, but it isn’t always clear-cut either. Removing and reinstalling solar just to end up with similar capacity locks in the same limitations for another decade. You’re left with a cleaner version of the same problem.
This is where repowering changes the equation. Instead of fixing individual components, the focus shifts to upgrading the system’s capacity and efficiency in one move. For many homes, the cost difference between repairing a tired 3kW system and installing a modern, high-efficiency system is smaller than expected, and the performance gap is far larger.
Why repowering makes more sense now
Repowering today is about redesigning your solar system for how energy is actually used now. Modern panels are significantly more efficient than those installed in 2016.
Advances in cell design, particularly with N-Type technology, mean today’s panels generate more power from the same roof space, perform better in heat, and degrade more slowly over time. That allows many households to move from a 3kW or 5 kW system to 10kW or more without needing extra roof area.
The economics have changed as well. The cost per kilowatt of installed solar has fallen, while electricity prices have climbed. As a result, upgrading to a larger, more efficient system often delivers better bill reduction than pouring money into keeping an ageing system alive.
Repowering also future-proofs the home. A modern system is better matched to battery storage, EV charging, and electrification upgrades. Instead of designing around the limits of old solar, the system becomes a foundation for lower energy costs over the next decade.
The economics: old 3kW vs new 10kW
| Factor | 10-Year-Old 3kW System | Modern 10kW System (2026) |
| Typical install era | 2015–2017 | 2025–2026 |
| Real-world output today | Reduced by up to 20–30% | Near full rated capacity |
| Panel technology | Older P-Type | High-efficiency N-Type |
| Roof space efficiency | Low | High |
| Ability to offset household demand | Limited | Covers most daytime usage |
| Feed-in reliance | High | Lower, more self-consumption |
| Inverter status | Often out of warranty | New, full warranty |
| Upgrade path (battery, EV) | Constrained | Designed to integrate |
| Cost effectiveness | Money spent to maintain limits | Money spent to expand value |
| Long-term bill impact | Modest savings | Significant bill reduction |
What this comparison highlights is value. Repairing or maintaining an older 3kW system puts money into preserving a ceiling on your savings. A modern 10kW system shifts that ceiling entirely, allowing solar to cover more of your actual energy use instead of just contributing to it.
The bigger risk
Keeping an ageing solar system doesn’t just limit what you save today. It can actively block future savings. Many older systems become the bottleneck when homeowners try to upgrade, forcing new decisions to work around outdated capacity and hardware.
A common example is battery storage. A small, underperforming solar system often can’t generate enough surplus to charge a battery effectively. The result is an expensive add-on that never reaches its potential. The same issue shows up with EV charging, where daytime solar simply isn’t enough to meaningfully offset charging loads.
Network rules and tariffs are also changing. In many areas, export limits and reduced feed-in values mean undersized systems lose even more value over time. If your solar can’t cover your own usage first, exporting small amounts becomes far less helpful than it once was.
The risk is that it quietly locks your home into higher grid reliance for years to come. Designing future upgrades around a weak solar foundation often costs more in the long run than addressing the system itself.
Who should seriously consider an upgrade?
Repowering isn’t for every household, but some situations make it far more likely to pay off. If your solar system falls into any of the categories below, an upgrade is often worth running the numbers on:
- Your system was installed before 2018
- Your system is 3kW-5kW and unchanged
- Your electricity bills are still high
- Your inverter is out of warranty
- You’re planning a battery, EV, or electrification upgrades
- Your export credits feel disappointing
If several of these apply, the question you should ask is whether the system is still worth keeping in its current form.
Zombie solar costs quietly
Most older systems don’t fail in a way that forces action. They keep running just well enough to avoid attention, while quietly delivering less value each year. That’s what makes zombie solar so expensive. The cost shows up slowly, through higher bills and missed savings, instead of a single obvious breakdown.
In 2026, the decision is about whether your solar system still matches how your home uses energy today and how it will use energy in the years ahead. For many households, auditing an older system and considering a full repower delivers more clarity than another repair ever could.
Solar should be an asset that actively reduces reliance on the grid, not a relic that looks busy while holding your savings back.
Energy Matters has been in the solar industry since 2005 and has helped over 40,000 Australian households in their journey to energy independence.
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