How to check your solar panel health in Perth: degradation, inspection, and testing

To check your solar panel health in Perth, start with your own monitoring data: pull the last 12 months and compare it to your installer's original generation estimate. A healthy panel loses only a small fraction of its output each year, so a system around 10 years old should still produce roughly 93-96% of its original yield. If your output sits well below that, or it has stepped down suddenly, the next move is a professional inspection using thermal imaging, electroluminescence (EL) testing, or I-V curve tracing to find the failing panels.

Panel degradation is gradual, which is exactly why it slips past most owners. A 10% drop in output doesn't trip any alarms, but on a typical Perth system that lost generation quietly adds up over a year. Here's how to tell normal ageing apart from a real fault, and what to do about it.

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What counts as normal panel degradation, and what doesn't?

A small annual decline is built into how panels age. The question is whether yours is tracking the warranty curve or falling off it.

Normal degradation. Most modern panels are warranted to lose only a small percentage of output per year. Standard PERC panels degrade at around 0.5% a year; back-contact (IBC) panels are slower, closer to 0.25% a year. After 10 years, a healthy system should still produce at least 93-96% of its original output.

Early or abnormal degradation. A system producing 80% or less of its original output at the 10-year mark is underperforming against most modern panel warranties. Older PERC panels from the 2012-2016 vintages degraded faster (in the region of 0.5-0.8% a year), and some low-cost brands from that period aged worse still.

What causes panels to degrade faster than they should?

• Potential-induced degradation (PID): a voltage-related fault affecting cells around the edge of the module, more common in older systems built without PID protection. It can cut an affected panel's output by up to around 30%.
• Micro-cracks: invisible cell fractures from rough handling at install (dropped panels, poor corner padding) or hail. Cracked cells carry higher resistance and produce less.
• Delamination: the protective encapsulant separating from the cell. It opens a moisture path and shows as bubbling or yellowing near the panel edges.
• Solder joint failures: internal connection faults that raise resistance and cause intermittent generation drops your monitoring may pick up.

Day-to-day Perth dust and pollen also drop output, but that is soiling, not degradation. Light rain clears most of it. For when cleaning is actually worth it, see our guide to solar panel cleaning in Perth, and for the long-run ageing picture, solar panel degradation in Perth.

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How do I tell if my panels are actually underperforming?

Before you pay anyone to climb on the roof, confirm the system is genuinely below par rather than just producing what the weather allows.

1. Download your monitoring data (iSolarCloud, Solar.web, Enlighten) for the last 12 months.
2. Compare it to your installer's original generation estimate, which should be in your quote documents.
3. If you don't have the estimate, use a rough Perth benchmark below.

A 6.6kW north-facing Perth system should produce approximately:

• Summer month (Dec/Jan): ~1,100-1,300 kWh
• Winter month (Jun/Jul): ~400-500 kWh
• Annual total: ~9,500-10,300 kWh

If output is 10-15% below expectation: that can point to degradation, more shading (a tree that has grown), soiling, or an underperforming inverter. Worth investigating further.

If output is suddenly 20% or more below expectation: a panel or string fault has likely occurred. Check your inverter fault codes; both the inverter display and the monitoring app show fault history. Our solar inverter error codes guide for Perth explains the common ones, and solar monitoring apps in Perth covers how to read the data properly.

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What can I check from the ground without roof access?

Some faults are visible from the backyard if you know what you're looking at:

• Discolouration: yellowing or browning seen through the glass points to heat damage or encapsulant breakdown.
• Delamination: edge bubbling or white hazing at the panel edges or around the cell lines.
• Bird-dropping build-up: especially on panels near roof peaks or eaves.
• Visible cracks: rare, but possible after hail. Look along the cell lines, where cracks throw faint shadow lines across the cells.
• Frame damage: bent frames or missing mounting clips can flag damage done during installation.

A binocular check from the ground is free and catches the obvious problems. It won't find micro-cracks or PID, which is where professional testing comes in.

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When is a professional inspection worth it, and what does it find?

For systems five years or older, or any system throwing monitoring anomalies, a professional inspection goes where a ground check can't. There are three main methods, and they are usually paid add-ons priced per job, so ask for a quote for your system size and roof access.

Thermal imaging (IR inspection). An infrared camera spots hot cells and bypass diodes, which signal micro-cracks, PID, or failing cells. It is the quickest of the three and a common first step.

Electroluminescence (EL) testing. EL passes a current through the panel and photographs the light it emits; cracks and dead cell areas show up as dark regions. It is the most thorough way to find micro-cracks that thermal imaging misses, and the most involved to run, since panels often have to be disconnected and imaged carefully. It is the priciest of the three, so get a quote.

String-by-string I-V curve tracing. The technician clips a specialised meter (an I-V tracer) to each string and records its current-voltage curve. A healthy string traces a characteristic S-shaped curve; degraded or shaded strings show clear anomalies. Most Perth solar service companies offer it as part of a system audit, so request a quote.

Prices for these specialist tests vary by provider, system size, and access, so get a written quote before you book.

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Can I claim warranty on panels that are degrading too fast?

Often, yes, if the panels are still within warranty and clearly falling below the warranted degradation curve.

First, know which warranty applies. Australian residential panels typically carry a product warranty of 10-25 years and a performance warranty of 25 years. A few premium models extend the performance warranty further, but 25 years is the standard you should expect on the datasheet.

Then work through the claim:

1. Document the underperformance with 12 months of monitoring data.
2. Contact the panel manufacturer directly (not only the installer) with that data and your original warranty paperwork.
3. Get a professional assessment. Manufacturers usually want evidence from an SAA-accredited inspector, or the results of I-V tracing or EL testing.

Claims get harder when the manufacturer has no local office. Chinese brands with Australian distribution (Longi, Jinko, JA Solar, Trina) handle warranty claims through their Australian distributors, so ask your installer who the local distributor is when you buy. For the detail on warranty terms and what each one covers, see our solar panel warranty guide for Perth and making a solar warranty claim in Perth.

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When should I prioritise a panel health check?

Move a health check up your list if any of these apply:

• The system is 8 or more years old and monitoring shows a gradual output decline.
• It was installed before 2016 (older technology, higher PID risk).
• Your area copped a hailstorm (micro-cracking is often invisible to the eye). Our hail-resistance guide for Perth panels covers what to look for after a storm.
• Output stepped down suddenly with no shading or soiling to explain it.
• The panels are from a brand with poor warranty support, especially one that has since left the market.

A Perth system installed before 2018 is worth a professional check. Your monitoring data is the first diagnostic tool you have: if output runs 10% or more below expected on clear days after allowing for soiling, book an I-V trace or thermal inspection. Performance warranty claims are open while panels are in warranty and underperforming against the warranted curve, so it pays to act before the term runs out.