Annual solar system health check for Perth homeowners
Perth solar systems run mostly unattended — but a once-a-year check of your monitoring data, a visual inspection, and a cleaning confirms everything is performing as expected and catches problems before they cost you money.

A well-installed Perth solar system needs minimal maintenance — the panels are solid-state with no moving parts, and modern inverters are designed to run unattended for a decade. But an annual check takes 30–60 minutes and can catch issues that cost you hundreds in lost generation if left undetected.
Step 1: Compare generation against last year (monitoring review)
What to look for: Pull up your monitoring platform (Fronius Solar.web, Sungrow iSolarCloud, SolarEdge monitoring, Enphase Enlighten) and compare this month's generation to the same month last year.
Expected year-on-year variation:
- Panel degradation: 0.35–0.55%/year for PERC panels, 0.28–0.40%/year for TOPCon panels
- So a system generating 10,000 kWh in year 2 should generate approximately 9,960–9,945 kWh in year 3 (all else equal)
- A 10–15%+ drop in generation over one year (adjusted for similar weather) is a flag worth investigating
Weather-adjusted comparison: Perth's solar irradiance varies year-to-year by approximately 5–10%. A generation drop of 3–5% isn't necessarily a problem if the reference year was unusually sunny. Compare more than one year if possible.
String-level comparison: If your inverter has multiple MPPT inputs (separate strings), compare string outputs. A string generating 15–20% less than the others is underperforming — possible causes: partial shade, connection issue, panel defect.
Step 2: Visual inspection from ground level
A safe inspection from ground level (no ladder required) can identify:
Panel surface:
- Visible cracking or delamination — panels with cracks have compromised cell connections
- Heavy soiling, bird droppings, or vegetation debris
- Snail trail discoloration (brown lines following busbar patterns — see our panel defects guide)
- Unusual colour changes or yellowing (EVA delamination)
Mounting system:
- Panels still secured flat against the racking (no lifted corners or edges)
- No visible corrosion on mounting hardware (particularly important in coastal Perth — Cottesloe/Scarborough/Rockingham should check annually)
- No panels visibly shifted from their original position
Cabling:
- DC cables visible from ground level: no UV cracking, no rodent damage where cables are accessible
- Conduit runs to the inverter: intact and secured
Inverter:
- Inverter status indicators: should show normal operation (green light on most brands)
- No unusual sounds from the inverter (buzzing, clicking)
- Ventilation clear: no wasps' nests or debris blocking inverter vents
Step 3: Check inverter error history
Most inverter monitoring platforms log faults and errors. Review the error log for the past 12 months:
- Occasional, brief MPPT faults: Normal, usually caused by temporary cloud cover or grid disturbance
- Repeated earth fault (Isolation Fault) events: Can indicate insulation degradation in the DC cabling or panels — worth investigating
- Grid overvoltage events (Vgrid): Common in Perth — the grid voltage at your property may be at the upper limit, causing the inverter to temporarily disconnect. Persistent Vgrid errors may be worth reporting to Western Power
- Anti-islanding trips: Should be rare; frequent trips may indicate grid instability at your connection point
Step 4: Panel cleaning assessment
Perth's climate and the Fremantle Doctor wind pattern means dust accumulation is moderate. Panels that are never cleaned will lose approximately 3–7% of annual generation from dust, bird droppings, and urban particulate buildup.
When to clean:
- After a prolonged dry spell (summer months, especially November–March)
- When bird droppings are visible from ground level
- If monitoring shows a generation plateau despite good irradiance
Cleaning method:
- Cool water (not pressurised) and a soft brush or squeegee
- Dawn/early morning before panels heat up (thermal shock risk with cold water on hot panels)
- No detergents, no high-pressure washers
- DIY safe only on single-storey roofs where you can access safely without a ladder
Step 5: Check battery storage health (if applicable)
For systems with battery storage:
State of health (SoH): Most battery management systems report SoH — the percentage of original capacity remaining. A 10kWh battery at 92% SoH effectively stores 9.2kWh.
Typical SoH by year:
- LFP chemistry: ~98% year 1, declining to ~90% by year 8–10
- NMC chemistry: ~97% year 1, declining to ~80% by year 8–10
If your battery's SoH has dropped more than expected, review cycle history and check whether the battery has been operating at high temperatures (>35–40°C ambient) or routinely deep-cycling below 10% SoC.
Battery charge/discharge cycles: Review the annual cycle count. An EV household may cycle the battery 365 times/year; a less active household 100–150 times/year. Most LFP batteries warrant ≥3,000–6,000 full cycles.
Step 6: Review your Synergy bill
A once-per-year comparison of your Synergy bills:
- Are you importing more than you expected? Check against monitoring data — consumption on the bill should roughly match imports shown in monitoring
- DEBS credits: compare export volume on the Synergy bill against exports shown in monitoring. Significant discrepancies suggest a metering or tariff issue worth querying with Synergy
- Supply charge: confirm the supply charge aligns with your tariff (A1 vs Midday Saver vs DEBS)
When to call a CEC-accredited installer
Flag the following for professional inspection:
- Repeated isolation/earth fault errors
- String generating >15% below the others with no shade explanation
- Any physical damage to panels, racking, or wiring
- Inverter showing no output despite good conditions
- Battery SoH declining faster than warranted
A CEC-accredited solar electrician can perform a formal inspection, thermal imaging scan, and electrical safety check. Cost: typically $150–$350 for a residential inspection.
The annual check is not a service appointment — it's a 30-minute review of your monitoring data and a ground-level visual. It catches problems early. The cost of a missed inverter fault or shaded panel is measured in missed generation across months.
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