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

Perth solar panels installed 5–15 years ago may be significantly underperforming without the owner being aware. Panel degradation is gradual — a 10% reduction in output doesn't trigger alarms, but at $300–$500/year in lost value it adds up. Here's how to assess your system's health.

Normal vs abnormal degradation

What's normal: Solar panels are warranted to lose no more than 0.35–0.60%/year in output (varies by brand and vintage). After 10 years, a healthy system should produce at least 93–96% of its original output.

What's early degradation: Systems producing 80% or less of original output at 10 years are underperforming against most modern panel warranties. Older PERC panels from 2012–2016 vintages had higher degradation rates (0.5–0.8%/yr) and some low-cost brands from that period performed worse.

Common causes of abnormal degradation:

• Potential-Induced Degradation (PID): A voltage-related degradation affecting cells on the periphery of the module. More common in older systems without PID protection. Can reduce affected panel output by 10–30%.
• Micro-cracks: Invisible cell fractures from installation (dropped panels, inadequate corner padding) or hailstorm damage. Micro-cracked cells have higher resistance and lower output.
• Delamination: Separation of the protective encapsulant from the cell. Creates moisture ingress paths and visible bubbling or yellowing at panel edges.
• Solder joint failures: Internal connection failures causing increased resistance — intermittent generation drops that monitoring may catch.

Step 1: compare output to expectations

Before arranging an inspection, check whether your system is actually underperforming or just producing what it should in current conditions.

What to check:

1. Download your monitoring data (iSolarCloud, Solar.web, Enlighten) for the last 12 months.
2. Compare to your installer's original generation estimate (should be in the quote documents).
3. If you don't have the estimate, a 6.6kW north-facing Perth system should produce approximately:
   • Summer month (Dec/Jan): ~1,100–1,300 kWh/month
   • Winter month (Jun/Jul): ~400–500 kWh/month
   • Annual total: ~9,500–10,800 kWh/year

If output is 10–15% below expectation: This may indicate degradation, shading increase (tree growth), soiling, or inverter underperformance. Investigate further.

If output is suddenly 20%+ below expectation: A panel or string fault has likely occurred. Check inverter fault codes (the inverter display and monitoring app both show fault history).

Step 2: visual inspection from ground level

You can identify some issues without roof access:

• Discolouration: Yellowing or browning panels (visible through the glass) indicate heat damage or encapsulant degradation.
• Delamination: Edge bubbling or white hazing at panel edges or around cell lines.
• Bird dropping concentration: Particularly on panels near roof peaks or eaves.
• Visible cracks: Rare but can occur after hail. Look at the cell lines — cracks create visible shadow lines across cells.
• Frame damage: Bent frames or missing mounting clips can indicate installer damage during installation.

Step 3: professional inspection

For systems 5+ years old or those showing monitoring anomalies, a professional inspection adds:

Thermal imaging (IR inspection): An infrared camera identifies hot spots in panels — cells or bypass diodes running hot indicate micro-cracks, PID, or failing cells. The cost of thermal imaging inspections in Perth is typically $300–$800 depending on system size and access.

Electroluminescence (EL) testing: EL testing passes a current through the panel and photographs the resulting light emission — cracks and inactive cell areas show as dark regions. This requires panels to be removed (or at least disconnected and imaged in place), so it's more expensive ($800–$2,000 for a typical residential system). EL testing is the gold standard for detecting micro-cracks invisible to thermal imaging.

String-by-string I-V curve tracing: The installer clips a specialised meter (I-V tracer) to each string and records the current-voltage curve. A healthy string produces a characteristic S-shaped curve; degraded strings or shaded panels show anomalies. Most professional solar service companies in Perth offer I-V tracing as part of system audits ($400–$900).

Warranty claims on degrading panels

If your panels are within warranty (product warranty typically 10–25 years; performance warranty typically 25–30 years) and are underperforming against the warranted degradation curve:

1. Document the underperformance with 12 months of monitoring data.
2. Contact the panel manufacturer (not just the installer) with the monitoring data and your original warranty documentation.
3. Obtain a professional assessment — manufacturers will typically require evidence from a CEC-accredited inspector or the results of I-V tracing or EL testing.

Panel warranty claims in Australia can be complex if the manufacturer has no local office. Chinese manufacturers with Australian distribution (Longi, Jinko, JA Solar, Trina) have warranty claim pathways through their Australian distributors — ask your installer who the local distributor is when you buy.

When to prioritise a health check

• System is 8+ years old and monitoring shows a gradual output decline
• System was installed pre-2016 (older technology; higher PID risk)
• Perth hailstorm event (micro-cracking is often invisible to the naked eye)
• Sudden step-down in output not explained by shading or soiling
• Panels from a brand with poor warranty support (especially brands that have since exited the market)

Perth solar systems installed before 2018 are worth a professional health check. Monitoring data is your first diagnostic tool — if output is 10%+ below expected on clear-weather days after accounting for soiling, arrange an I-V trace or thermal inspection. Performance warranty claims are available if panels are within warranty and underperforming against the warranted curve.