Solar inverter warning lights and error codes in Perth: what they mean

A handful of inverter warnings are genuine safety faults, an insulation fault or an arc-fault trip needs a licensed electrician, not a reset, so check for those first. We flag them clearly below so you know when to stop and pick up the phone. Most of the rest clear on their own or are easy to understand from your couch. Start by opening your monitoring app and checking one thing: is the system generating right now? If it shows power flowing on a sunny day, the warning was probably a transient fault that cleared itself, and you can relax. If it shows 0W on a clear day, the fault is live and this guide will tell you what it means and who to call.

Here's the fast version, then the detail for each brand and fault type.

The 30-second triage

1. Open your monitoring app. Fronius uses Solar.web, Sungrow uses iSolarCloud, GoodWe uses the SEMS Portal, and SMA uses Sunny Portal.
2. Check today's output on a sunny day. Power above 0 kW means the inverter is working; the warning may already be history.
3. Look at the physical light on the inverter. Green is healthy. Red is an active fault. Orange or flashing is usually a warning or a communication drop.
4. Match the fault to a category below. Grid, insulation, over-temperature, DC voltage, communication, or arc-fault.
5. Safety faults stop here. Insulation (ISO) and arc-fault (AFCI) mean switch off at the DC isolator and call a licensed solar electrician. Do not reset them.

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How do I tell if my inverter is actually broken or just showing an old fault?

Open your inverter monitoring app and look at live output. If the app shows generation on a sunny day, with kW output above zero, the inverter is working, and the error was most likely a transient fault that cleared on its own.

If the app shows 0W on a sunny day, or a long gap with no data, the fault is active and worth chasing down. The rest of this guide walks through the common causes.

One quick check that saves a lot of worry: a blank monitoring app is not the same as a dead inverter. Communication can drop while the inverter keeps generating happily. More on that under the communication section below.

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What do the common inverter warnings actually mean?

Perth inverters throw a fairly predictable set of faults. Here are the six you're most likely to see, what each one means, and whether you can act on it yourself.

Grid fault or grid code error

What it means: the inverter saw the grid supply drift outside its allowed voltage or frequency window and disconnected to stay safe. Australian grid rules (AS/NZS 4777.2) require every inverter to shut down when grid voltage or frequency moves outside set limits. This is the inverter doing its job, not failing.

Common causes:

• A brief grid voltage spike or dip, which is common in Perth suburbs where a lot of homes export solar around the middle of the day.
• A Western Power planned or unplanned outage.
• Power-quality problems on the local street network.

What to do: if the fault has cleared and the inverter is generating again, there's nothing to do. Grid faults usually self-resolve. If the same fault trips several times a week with no obvious outage, ring your electricity distributor, Western Power. Sustained voltage problems on your street are a network issue for them to investigate, not a fault in your gear.

Insulation resistance fault (ISO or RCD fault)

This one is a genuine safety fault, so treat it seriously.

What it means: the inverter has detected low insulation resistance on the DC side, between the solar panels and earth. That can point to damaged DC wiring, water getting into a junction box, a cracked panel, or a failing DC isolator.

What to do: don't try to diagnose this yourself. Switch the solar system off at the DC isolator near the inverter, the red rotary switch you can reach from the ground. Don't go onto the roof to reach the rooftop isolator yourself, that's a job for whoever you call next. Then call your installer or a licensed solar electrician. This fault should never be reset without someone investigating the cause first. The related risk of a failing DC isolator is covered in our guide to DC isolator fire risk on Perth rooftops.

Over-temperature warning

What it means: the inverter itself has overheated and either throttled its output or shut down to protect its electronics. This shows up most in Perth summers, especially when the inverter is bolted somewhere with poor airflow or catching direct afternoon sun.

What to do: check where the inverter is mounted. Is it in direct sun, particularly that harsh western afternoon light? Is there room around it for air to move? A lot of Perth inverters live in unventilated garages, which is exactly where heat builds up. If the warning appears on hot days and clears by evening, the fix is usually about the location: add shade, improve ventilation, or in some cases relocate the unit.

If it's already well shaded and well ventilated but still faulting on temperature, the cooling fan or something internal may be failing. That's an installer callout.

DC high voltage or string voltage out of range

What it means: the DC voltage coming off the panels went above the inverter's maximum input. Panel open-circuit voltage climbs as the panels get colder, so this can happen on a very cold, clear morning before the sun warms the array.

Is it normal? A rare cold-morning spike is normal physics and nothing to worry about. Repeated faults are not. If the warning shows up on warm days, or keeps recurring through the year, that usually points to a wiring problem: panels wired in the wrong string configuration, or too many panels in series for the inverter.

What to do: occasional cold-morning events, leave them. Anything recurring or happening in mild weather, contact your installer, because the string may need to be rewired.

Communication or monitoring disconnected

Good news first: this is not a generation fault, and it's the most common warning of the lot.

What it means: your monitoring app shows no data, but the inverter is very likely still generating away on the roof. The link between the inverter and the monitoring server drops over WiFi or Ethernet all the time, and it doesn't touch your solar output.

Signs it's only a communication issue:

• The inverter's own display, if it has one, shows normal generation figures.
• The physical LED on the inverter is green, not red.
• Neighbours with the same inverter brand also have gaps in their monitoring.

What to do: check your home WiFi is up. Restart the inverter's WiFi or Ethernet link using the manufacturer's app or manual. If the gap runs past 48 hours and your WiFi is fine, ask your installer to check the communication module. For a deeper look at reading the apps themselves, see our guide to solar monitoring apps for Perth homes.

Arc fault detection (AFCI) trip

This is the second genuine safety fault on the list.

What it means: some newer inverters include Arc Fault Circuit Interrupter (AFCI) protection that detects electrical arcing on DC wiring, a real fire risk in a roof cavity. When it detects an arc, it shuts the system down.

What to do: a licensed solar electrician needs to inspect the DC wiring. Do not reset an AFCI trip without that inspection. DC arcing can start fires in the roof space, so this is not one to clear and hope.

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Which fault code matches my inverter brand?

Every brand names its faults differently and shows them in its own app. The single most reliable move for any brand is to read off the exact code your unit is showing, then look that code up in the manufacturer's support portal, because the same fault family can carry different code numbers across firmware versions.

Fronius: faults appear as numeric state codes in the Solar.web app, each with a short description. Read the exact code your inverter is displaying and look it up in the Fronius support portal for the current meaning. The code families broadly track the categories above: grid, communication, and insulation faults each have their own range.

Sungrow: codes show on the LCD display and in the iSolarCloud app, which gives a description for each. Grid-voltage codes are usually transient and self-clear once the grid settles. An insulation (ISO) fault is the safety fault covered above and needs an electrician. For anything you can't identify, read the exact code and check it against Sungrow's support material.

GoodWe: codes appear in the SEMS Portal. If you have a battery connected, battery fault codes are listed separately from inverter fault codes, so check which one is actually flagging. For any GoodWe code the app doesn't explain, contact your installer.

SMA: use the Sunny Portal or the Sunny Boy Smart Energy app. SMA works on a condition and event system: red conditions are faults that need action, yellow conditions are warnings you can usually monitor. Look the event code up in SMA's event-code list on their support site.

If you're still choosing a brand rather than diagnosing one, our Perth inverter brands guide and how to read solar inverter specs cover what to look for before you buy.

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Should I call my installer or an electrician?

Both are valid first calls, and the right one depends on the fault. Here's the split.

Call your installer first for:

• Any recurring error that resets but keeps coming back.
• Over-temperature faults that persist past a hot afternoon.
• DC high-voltage warnings.
• A system that isn't generating with no obvious error showing.

Call a licensed solar electrician (SAA-accredited) directly for:

• An insulation or ISO fault.
• An arc-fault (AFCI) trip.
• Any fault where you switched the system off for safety and you're not sure it's safe to switch back on.
• A system that stopped generating after a storm or severe weather.

That last one comes up more than you'd expect in Perth. If a big blow has just been through, our guide to solar systems in Perth storms and extreme weather covers what to check. And whoever you call, it pays to know they're properly accredited: here's how to check a solar installer's credentials in Perth.

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If your inverter is showing an active fault and you're unsure what it means, your installer is the right first contact. They can pull the inverter's diagnostic log through their service tools, which shows far more detail than the consumer app. If the fault turns out to be the inverter itself failing rather than an external cause, our guides to inverter lifespan in Perth and what an inverter replacement costs walk through what comes next.