How long solar panels last in Melbourne, and what wears them out

Solar panel lifespan vs warranty life

Solar Victoria’s buyers guide puts it simply: there are no moving parts to wear out in a solar panel, just solid-state cells with very long lifespans. A warranty is the period the maker promises to fix or replace a faulty panel, not the time it will last. Like our other solar guides, the figures here come from the makers’ own documents and Solar Victoria. A solar system has three warranties:

• Product warranty covers faults in the panel’s materials and workmanship: 20 to 30 years for the panels we list.
• Performance warranty guarantees how much power the panel keeps: 87.4 to 92% after 25 to 30 years here. Solar Victoria expects any high-quality panel to keep at least 80% after 25 years.
• Workmanship warranty comes from the installer and covers the installation itself, not the equipment.

How solar warranties work

Solar panel degradation: how much power panels lose each year

Every panel loses a little power as it ages, most of it in the first year. The makers of the panels we list guarantee a loss of no more than 1 to 2% in year one and 0.25% to 0.4% a year after that. These are the ranges our previous site listed; your quote names the exact model.

In kilowatt-hours: a 6.6kW system on a north-facing Melbourne roof makes about 9,319 kWh a year when new, going by the PVGIS model for Mount Waverley, Melbourne. At the lowest guarantee above, 87.4% after 30 years, it would still make about 8,140 kWh a year (our arithmetic, before the weather). Every range here guarantees more than the 80% Solar Victoria expects of a high-quality panel.

What makes panels degrade

The IEA PVPS Task 13 reliability group tracks the main ways panels lose power:

• Light-induced degradation (LID): a drop that typically happens within the first few hours of light exposure, one reason makers allow more loss in year one. The IEA says it now matters little in gallium-doped and n-type cells.
• LeTID (light and elevated temperature): mainly affects p-type PERC modules; n-type TOPCon panels are substantially less susceptible.
• Potential-induced degradation (PID): caused by high system voltage.
• UV: some TOPCon and heterojunction panels lose power under UV in accelerated tests, a problem the IEA calls solvable.
• Thermal cycling: daily heating and cooling that can enlarge microcracks (below).

Every panel range we list uses n-type cells. Canadian Solar’s Australian datasheet claims anti-LeTID and anti-PID performance, and WINAICO’s Australian datasheet claims PID and LID resistance, with an IEC TS 62804-1 anti-PID certificate.

Real-world degradation vs the warranty

NREL’s review of nearly 2,000 measured degradation rates, from 40 years of field studies, found a median loss of 0.5% a year, and its 2016 update of more than 11,000 rates put the median for crystalline silicon at 0.5–0.6% a year. The makers we list guarantee 0.25% to 0.4% a year after year one. At the field median a panel would keep about 87.5% of its power after 25 years; the guarantees here range from 89.4% to 92% in year 25. Year one is allowed more, 1 to 2%, which leaves room for early drops such as LID.

What slower degradation is worth on a Melbourne roof over 25 years

Take the same 6.6kW system, about 9,319 kWh a year when new on a north-facing Melbourne roof. If its panels lost exactly what each warranty allows, this is what it would make over 25 years (our arithmetic, before the weather):

The slowest and fastest curves differ by about 1,800 kWh over 25 years, under 1% of the total. That is real but small next to the roof itself: an east or west roof makes about 13% less a year than a north one.

Compare the panels in full

Which way panels should face

What shortens a solar panel’s life?

One way a panel wears is through microcracks, which Solar Victoria describes as “tiny cracks in the cells that can enlarge over time with thermal cycling (as the panels heat up and cool down each day) or with poor handling practices”. They can cut a panel’s output. Four things speed up wear or damage a panel outright.

Hail

Panels are certified with ice balls fired at the glass under IEC 61215, and REC calls 25 mm the industry baseline. The Canadian Solar TOPHiKu6 and REC Alpha Pure-RX datasheets each list 35 mm under IEC 61215. The Winaico NCX48 glass-glass datasheet lists 45 mm under IEC 61215. REC also reports 55 mm hail at 33.9 m/s in Kiwa PVEL’s hail stress sequence. Phono Solar’s Helios datasheet gives hail up to 35 mm at 97.9 km/h without naming the test, so ask for the rating of the model on your quote.

Hail damage isn’t a manufacturing fault. Canadian Solar’s Australian warranty, for example, excludes power failures and surges, flood, fire, lightning, accidental breakage and “other events outside CSI Solar’s control”. Moneysmart lists storms among the insured events a home building policy names, and says the rebuild cost you insure can include solar panels, so check that your policy covers them. After a hailstorm, look from the ground, don’t climb onto the roof, and call a licensed electrician about any cracked glass: what to do after storm damage.

Heat and daily temperature swings

Panels heat up and cool down every day, and Solar Victoria says that thermal cycling can make microcracks grow. Heat matters for the inverter too. Solar Victoria’s maintenance guide warns: “Anything preventing air flow could overheat the inverter in hot weather and reduce its life.” Keep its vents and heatsink clear of dust and cobwebs.

Salt air near the coast

For homes near the bay or the coast, Solar Victoria points to IEC 61701, the standard for resistance against salt mist corrosion for solar modules installed in coastal areas. REC lists IEC 61701 (severity 6) for the Alpha Pure-RX. Winaico lists IEC 61701 for the NCX48 glass-glass. Canadian Solar’s Australian warranty excludes panels subject to “extraordinary hot, salt or chemical exposure”, so ask for the salt mist certificate of the exact model.

A poor installation

Solar Victoria says substandard assembly can shorten a panel’s life or speed up its degradation, and rough handling on the way to the roof can enlarge microcracks. Canadian Solar’s warranty doesn’t cover improper installation, or a design that leaves the panels constantly shaded. Wear on other parts matters too: Energy Safe Victoria warns that an ageing DC isolator can let moisture in, a fire risk, and both it and Solar Victoria ask for a service at least every 2 years by a licensed A-Grade electrician, preferably accredited by Solar Accreditation Australia. Solar Victoria says regular maintenance can extend the life of a rooftop system.

Solar servicing and repairs

Inverters and batteries wear out first

Solar Victoria’s inverter guide says panels should last more than 25 years, but inverters are not generally expected to last much more than 10 or 15, so you can expect to replace the inverter at least once. When it fails, the panels make no power until it is repaired or replaced. Solar Victoria suggests an inverter warranty of at least 5 years. The makers of the inverters we list offer:

• Sungrow: 10 years from installation in Australia (at most 11 years from manufacture).
• Fronius: 10 years when the inverter is registered on Fronius Solar.web within 30 months of delivery.
• Alpha ESS: 10 years product warranty (Australian datasheet).

Home batteries

A battery is the other part that ages faster than the panels. The batteries on our battery comparison carry maker warranties of 10 to 15 years, promising 70% of their capacity at 10 years. The battery lifespan guide explains the throughput limits and temperatures behind those numbers.

How long solar batteries last

How solar inverters compare

When does an old solar system need work?

Age alone isn’t a reason to replace working panels. Act when one of these happens:

• The inverter fails or shows faults. Usually that means a new inverter, not new panels.
• Output drops more than the warranty allows. Compare your monitoring app’s figures with the same months in earlier years (the weather varies, so look at several); output well below the performance guarantee can support a warranty claim.
• A service finds damage. Solar Victoria says a service looks for cracks, chips and discoloration, and the record can support a warranty claim on the panels.
• You use more power now. A bigger household, a battery or an electric car can outgrow an old, small system.

Few households add panels to an old system, Solar Victoria notes, and those who do often find that changed standards mean a new inverter anyway. Victoria’s premium feed-in tariff ended on 1 November 2024, so extending a system no longer risks losing it. We can inspect the system and tell you whether it needs a repair, a new inverter, more panels or a new system.

Upgrading an old solar system

What happens to solar panels at the end of their life?

In Victoria it has been illegal to put e-waste in household rubbish or landfill since 2019, and Solar Victoria counts solar panels, inverters and energy storage equipment as e-waste at the end of their life. Old panels must go to a lawful e-waste collection point or solar PV recycler, and Solar Victoria says specialist recyclers can recover up to 90% of a panel for reuse. An installer who removes panels must ensure the waste is taken to a place authorised to receive that type of waste. Taking a system down is electrical work for a licensed electrician.

Solar panel removal and recycling

Solar panel lifespan: your questions