Annual solar system health check for Perth homeowners

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.

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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.

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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

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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

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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

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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.

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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)

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When to call an SAA-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

An SAA-accredited solar electrician can perform a formal inspection, thermal imaging scan, and electrical safety check. Cost: typically $150–$350 for a residential inspection.

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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.