Why a Brand’s History in Australia Matters More Than the Number on the Warranty Certificate

1. Nothing happens on the twenty-fifth birthday

One of the most persistent misunderstandings in solar is that panels have an expiry date. People hear “25-year warranty” and picture a system that works for twenty-five years and then stops.

That is not how panels fail, and mostly it is not how they behave at all. A solar panel is a sheet of glass over a silicon wafer with no moving parts, sealed in a laminate and framed in aluminium. It does not wear out in any mechanical sense. What it does is fade, slowly, predictably, and considerably more slowly than most people expect.

The useful question is not how long panels last. It is how much output they will still be delivering at a given point, and what will actually break before then.

2. What does the field data actually show?

The most widely cited work comes from the United States National Renewable Energy Laboratory, which analysed degradation across nearly 2,000 solar installations worldwide and found a median degradation rate of 0.5 per cent per year for crystalline silicon modules. That figure has proven durable, holding up across subsequent and much larger datasets, with more recent meta-analysis placing the median in the range of roughly 0.5 to 0.7 per cent per year.

Independent long-term field work by the United States National Institute of Standards and Technology reached the same median of 0.5 per cent per year across a wide range of crystalline silicon modules. Two large independent bodies of research converging on the same number is about as good as evidence gets in this field.

What that means in practice is straightforward. Degradation compounds, so a panel losing 0.5 per cent annually is not losing a fixed number of watts each year but a fixed proportion of what it currently produces.

Figures are compounded from the stated annual rate. They do not include a separate first-year light-induced degradation step.

The gap between the top and bottom rows is around sixteen percentage points of output at year 25. That is the practical value of buying a well-made panel, and it does not show up anywhere in the first year of ownership.

3. Are panels actually getting better at this?

Yes, and the improvement is more meaningful than the efficiency gains that get all the marketing attention.

Older systems from the 1990s and early 2000s typically degraded at 0.7 to 1.0 per cent per year. Modern modules, particularly those using N-type cell architectures, sit at the low end of the distribution around 0.25 to 0.30 per cent. Recent field monitoring of current modules from manufacturers including Jinko, Trina and LONGi has shown median annual degradation of roughly 0.3 to 0.6 per cent, with most of the loss occurring in the first year.

The main reason is a change in silicon type. P-type PERC cells, the mainstream technology from roughly 2015 to 2023, suffer boron-oxygen light-induced degradation, a chemical effect causing one to three per cent of output to disappear within the first weeks of sunlight exposure. N-type silicon does not contain the boron-oxygen defect pair responsible, so that first-year loss is largely eliminated. It is a real durability improvement rather than a marketing one, and it is the strongest technical argument for buying N-type panels today.

4. Why does the number on your bill fall faster than the panel degrades?

Because the panels are only part of the system, and this distinction causes a lot of unnecessary worry.

Module degradation measures the decline in a panel’s output when tested under standard conditions. That is where the 0.5 per cent median comes from. System degradation measures the decline in electricity actually delivered to your home, and it is a different and larger number. NREL’s system-level analysis found a median closer to 0.75 per cent per year.

The difference is everything between the cells and your switchboard: inverter efficiency declining with age, soiling accumulating on the glass, resistance rising in cabling and connectors, and gradual mismatch between panels as they age at slightly different rates. Some of that is recoverable through cleaning and maintenance. Some is not.

There is also a climate effect. Systems in hot environments degrade measurably faster than those in mild ones, which is directly relevant to a Queensland roof. A panel that would lose 0.5 per cent a year in a temperate climate will typically lose more in sustained heat.

5. What actually fails first?

Almost never the panels. In our experience, and consistently in the published failure data, the order looks like this.

1. The inverter. It contains the most active electronics, runs hardest, cycles daily, and generates its own heat. Most Australian systems will need at least one inverter replacement across the life of the panels. This is normal and should be budgeted for rather than treated as a failure of the system.
2. Connectors and terminations. DC connectors, junction boxes and isolators are where the majority of real-world faults appear. These are largely installation-quality issues rather than product issues. Mismatched connector brands, poor crimps and inadequate weatherproofing are all avoidable at install time and all cause problems years later.
3. Rooftop isolators. A well-known Australian weak point, particularly on older systems, where water ingress and ultraviolet degradation of enclosures cause failures and in some cases fires.
4. Backsheet and encapsulant. On genuinely old or poorly made panels, the polymer layers can yellow, delaminate or crack after decades of ultraviolet and thermal cycling. This is a slow failure mode and is rare on quality modules within their warranted life.
5. The cells themselves. Microcracks from hail, mechanical stress during installation, or transport damage can progress over time. Cell-level failure that is not caused by external damage is uncommon.

The practical conclusion is that installation quality has more influence on how long a system lasts than the panel brand does. A well-made panel installed badly will fail before a mid-range panel installed properly.

6. What does Australia do to a solar panel?

More than most of the international data accounts for, which is why local context matters when reading global degradation figures.

• Ultraviolet intensity. Australia has among the highest UV levels of any populated country. UV drives polymer degradation in the backsheet and encapsulant, and it is the mechanism behind several long-term failure modes.
• Heat. Panels are rated at 25 degrees Celsius. Australian roof-mounted panels routinely reach 65 to 75 degrees in summer. Sustained heat accelerates every chemical degradation process in the laminate, and heat is the single largest environmental factor in Queensland.
• Thermal cycling. The daily swing between overnight low and midday high stresses solder joints and cell interconnects. Inland areas with large diurnal ranges are harder on panels than the coast.
• Humidity. Subtropical South East Queensland combines heat with high humidity, which is the specific combination that drives moisture ingress and corrosion. Damp heat testing exists precisely because of climates like ours.
• Coastal salt. Salt mist accelerates corrosion of frames, mounting hardware and electrical connections. Most manufacturers exclude installations within a defined distance of the ocean, commonly 500 metres, unless a salt-mist certified product is specified. This is a genuine warranty condition and is worth confirming against your specific address.
• Hail. South East Queensland gets severe hail. Panels are impact tested, but a severe storm can cause microcracking that is invisible from the ground and only shows up later as reduced output. After a significant hail event a system is worth checking properly, and the damage may be an insurance matter rather than a warranty one.

None of this means panels do badly here. It means the difference between a well-built panel and a cheap one shows up faster in Australia than almost anywhere else, and that independent stress testing (thermal cycling, damp heat, mechanical load, hail) tells you far more about how a module will age on your roof than its efficiency rating does.

7. What is the warranty actually promising?

Two separate things, and they are frequently confused in quotes.

The product warranty covers defects in the panel itself: manufacturing faults, delamination, frame failure. This is typically 12 to 25 years depending on the manufacturer and tier.

The performance warranty guarantees a minimum output at defined milestones. A typical modern N-type warranty guarantees around 98 per cent after the first year, then a maximum annual decline, ending at somewhere between 87 and 90 per cent of nameplate at year 25 or 30. Older PERC-generation warranties commonly ended around 80 to 84 per cent at year 25.

Two things are worth understanding about performance warranties. First, they are deliberately conservative: manufacturers warrant a level they are highly confident of exceeding, which is why real-world degradation consistently outperforms the warranted curve. Second, claiming against one is genuinely difficult, because you must demonstrate that output has fallen below the warranted line after accounting for weather, soiling, shading and inverter behaviour. That requires monitoring data over time, which is a practical argument for having a system that logs performance properly from day one.

8. Should you replace an old system?

Usually not because the panels have failed, and this is worth thinking about carefully because it is where a lot of money gets wasted.

A fifteen-year-old system is probably producing somewhere in the region of 90 per cent of what it originally did, assuming reasonable quality and no physical damage. The panels are not the problem. The problem, if there is one, is usually that the system is far too small for the household it now serves, a legacy array sized for a premium export tariff, on a house that has since acquired air conditioning, a heat pump and possibly an electric vehicle.

That is a capacity question, not a lifespan question, and the answers are different. Adding capacity alongside a functioning older array is frequently better value than replacing it. Where replacement does make sense is when the inverter has failed and is obsolete, when the array occupies roof space that a modern system would use far more productively, or when the existing installation has safety or compliance issues that make it uneconomic to maintain.

The one situation that genuinely requires care is a system on a legacy premium feed-in tariff, where modifications can affect eligibility. That needs to be worked through before anything is touched.

9. How to get the most life out of a system

• Insist on quality at the connection points. Matched connectors, correct crimping, proper weatherproofing and quality isolators prevent the majority of real-world faults. This is where installation quality either earns or costs you years.
• Monitor it. A system that logs performance lets you notice a fault in weeks rather than at the next bill, and gives you the evidence needed for a performance warranty claim.
• Keep the glass reasonably clean. Soiling is one of the recoverable components of system-level degradation. In most of South East Queensland rainfall does much of this, but dust, pollen and bird activity accumulate.
• Manage shading as vegetation grows. A tree planted the year the system went in becomes a genuine production problem a decade later.
• Have it inspected periodically. A visual and electrical check every few years catches connector degradation, isolator failure and mounting issues before they become expensive.
• Check the system after severe weather. Hail damage in particular is often invisible from ground level.

10. The short answer

A quality solar panel installed properly in South East Queensland should still be producing around 85 to 90 per cent of its original output after twenty-five years, and will keep generating well beyond that. The panels will very likely outlive the inverter, possibly by two inverters. They may well outlive the roof they are mounted on.

What determines whether you get that outcome is less about the brand on the frame than most quotes suggest, and more about the quality of the installation, the suitability of the design and whether anyone checks on the system across its life. Those are the parts you have most control over.

Fred Amiri
Licensed electrician and accredited solar designer. Fred designs and installs every Energy Gate system personally across Brisbane, the Gold Coast and South East Queensland. No subcontractors.

Key takeaways

• Twenty-five years is a warranty period, not an expiry date. Panels fade rather than fail.
• The long-run median degradation rate is 0.5 per cent per year, which leaves roughly 88 per cent of output at year 25.
• Your bill falls faster than the panels degrade, because system losses include the inverter, soiling and cabling.
• The inverter is the practical lifespan limiter. Budget for at least one replacement.
• Installation quality matters more than the brand on the frame, and it matters more here than almost anywhere else.

Not sure how your existing system is holding up?

Most systems that seem to be underperforming are not failing, they are undersized, unmonitored or carrying a connector fault nobody has looked at. It is usually worth checking before it is worth replacing.