Find your fault
Eight faults cover almost everything that goes wrong with Australian rooftop solar. Each one explains what it usually turns out to be, whether the system is safe to leave running, and what you can safely check yourself before anyone drives out.
Red light or an error code — An error code is the inverter telling you which part failed
Inverters do not fail silently — they log the fault and show a code. Most codes fall into three families: a grid problem (voltage or frequency outside the limits the inverter is legally required to trip on), an isolation or earth fault on the DC side, or an internal hardware fault. The code decides whether this is a network job, a same-day safety job, or a repair.
Watch it. If the code mentions isolation, insulation, earth or Riso, treat it as the isolation-fault case below and shut the system down. Any other code is generally safe to leave running while you get it looked at.
Worth checking before anyone visits
- Photograph the screen, including the exact code — it is the single most useful thing you can give a repairer, and it is often enough to price the job before anyone drives out.
- Note whether the fault clears and comes back, or stays permanently. Intermittent points at the grid; permanent points at hardware.
- Check whether it happens at the same time each day. Late-morning-to-mid-afternoon faults are usually grid voltage.
Typical fix: Read the code, test the DC strings and the AC connection, then either escalate to the network operator, replace the failed component, or recondition the inverter.
Screen is blank — no lights at all — A completely dead inverter is usually power to it, not the inverter
A blank inverter with no lights at all is more often a supply problem than a dead unit: a tripped solar breaker in the switchboard, a switched-off AC isolator, or a failed isolator — isolators are one of the most common failure points on Australian rooftops, largely from water getting in. A genuinely dead inverter is the next most likely cause, and after roughly ten years it is the likeliest.
Safe to leave running. A dead inverter is not dangerous in itself. It is also not generating, so every day it stays dead costs you money — this is the fault people leave longest and it is the one with the clearest payback on fixing.
Worth checking before anyone visits
- Check your switchboard for a tripped breaker labelled solar, PV or inverter. If one has tripped, you may reset it once — if it trips again, stop and call an electrician.
- Check the AC isolator (usually a grey box near the inverter or the meter) is switched on.
- Check the rest of the house has power, so you are not chasing a solar fault during an outage.
Typical fix: Test the supply first, replace a failed isolator or breaker if that is the cause, and only then assess the inverter for repair or replacement.
Isolation, insulation or earth fault — Stop. Shut the system down and get a licensed electrician out
An isolation or earth fault means current may be leaking out of the DC side of your system — commonly because water has got into rooftop wiring, a connector or a junction. In the worst case that can make a metal roof, gutters or panel frames live at DC voltage, which is a shock and fire risk. Rooftop solar DC can be lethal and it does not switch itself off when the sun is up.
Shut it down now. Follow your system’s shutdown procedure (AC isolator off, then DC isolator off) if you can do so safely from ground level, and call a licensed solar electrician. Do not repeatedly restart it to see if it clears. Do not go on the roof. Do not open the switchboard or any isolator. This is licensed work.
Typical fix: Insulation-resistance testing across the DC strings to find where the leak is, then repair or replace the wet connector, cable run or junction — and make the array safe before anything is re-energised.
Drops out in the middle of the day — That pattern is grid overvoltage — and it is usually not your inverter
This is the most common inverter error in Australia and it is the one most often misdiagnosed as a broken inverter. When the voltage in your street rises above the limit — commonly around 255 V — Australian Standards require your inverter to disconnect. It shuts down exactly when the sun is strongest, because that is when every solar system in the street is pushing at once. The inverter is behaving correctly. The voltage is the problem, and voltage in the street belongs to your network operator.
Safe to leave running. Not a safety issue — the shutdown is the safety mechanism doing its job. It is a money issue: you lose your best generating hours every clear day it happens.
Worth checking before anyone visits
- Note the times it drops out. A tight late-morning-to-mid-afternoon band on sunny days is the signature.
- Check whether it recovers on its own once the sun drops. Overvoltage trips usually do.
- Check your monitoring app for the voltage reading at the moment it cut out, if your inverter reports one.
Typical fix: An electrician logs the voltage at your switchboard to prove the trip, then it goes to your network operator to correct the supply. Inverter settings can sometimes be adjusted within the Standard, but the underlying fix is the network’s.
Producing much less than it used to — Working, but not earning — the most expensive fault to ignore
A system that runs but underperforms is losing money quietly, every day, which is why it can go unnoticed for years. The usual causes are one dead string or a failed MPPT input (so half the array is offline while the inverter still reports "OK"), new shading, soiling, a failed optimiser or microinverter on one panel, or genuine panel degradation on an older array.
Safe to leave running. Not dangerous. But a half-dead array can look completely healthy from the ground and from the app — the drop is only visible if you compare against what the system should be making.
Worth checking before anyone visits
- Compare this month against the same month last year in your monitoring app, not against last month — solar output is seasonal and month-on-month comparisons mislead.
- Look for a step change on a specific date rather than a gradual slide. A step means something failed; a slide means shading, soiling or age.
- Check whether anything new is shading the roof — a neighbour’s build, a grown tree, a new antenna.
Typical fix: String-by-string testing against expected output to find the dead section, then replace the failed optimiser, microinverter, string fuse or MPPT input.
Bill went up or credits stopped — The bill is often the first place a solar fault shows up
Feed-in credits disappearing can mean the system stopped exporting — a fault, a tripped breaker, or an export limit — or it can mean nothing is wrong with the system at all and your retailer changed your feed-in rate or your plan. Both happen often enough that the first job is telling them apart, and that is a five-minute check, not a call-out.
Safe to leave running. Not a safety issue. Worth checking quickly though: if it is a fault rather than a tariff change, every billing period you wait is money you do not get back.
Worth checking before anyone visits
- Compare the feed-in rate on your latest bill against an older one. A rate cut is a retailer change, not a fault.
- Check the exported kWh figure on the bill, not the dollars. If exported kWh has collapsed, it is the system; if only the dollars moved, it is the tariff.
- Check your inverter is actually on and generating on a sunny day.
Typical fix: Confirm whether export has genuinely stopped, then trace it — inverter fault, tripped breaker, meter configuration, or an export limit applied by the network.
Storm, water, hail or animal damage — Visible damage means make it safe first, assess second
Hail, wind-lifted panels, water in the inverter or isolator, and cockatoos and possums chewing rooftop cabling are all routine causes of Australian solar faults. Damaged DC wiring on a roof is the same hazard as an isolation fault, and the damage you can see from the ground is often not all of it.
Shut it down now. If wiring is exposed, panels are cracked or lifted, or water has got into the inverter or an isolator, shut the system down from ground level if you can do so safely and keep people away from anything metal that connects to the array. Do not go up to look.
Worth checking before anyone visits
- Photograph everything you can see from the ground — it is what your insurer will ask for and what a repairer prices from.
- Check whether your home and contents policy covers rooftop solar. Many do, and a damage repair is one of the few solar faults that is often claimable.
Typical fix: Make the array safe, then a full assessment and a written report — repairs and replacements are usually staged around the insurance claim rather than done in one visit.
Not sure — something is not right — Not knowing which fault it is, is itself a normal starting point
Most people do not find out their solar has a problem from the inverter — they find out from a bill, or because they happened to walk past and notice a light was off. Systems can sit half-broken for years. A full system check exists exactly for this: it tests every part rather than chasing one symptom.
Watch it. If you can see any burn mark, smell anything hot, or the inverter mentions isolation, insulation or earth, stop and treat it as urgent. Otherwise it is safe to leave running while you get it checked.
Worth checking before anyone visits
- Take a photo of the inverter screen and any lights on it, whatever they say.
- Open your monitoring app if you have one and compare this month with the same month last year.
- Note roughly when you last know it was working properly.
Typical fix: A full system check — DC strings, inverter, isolators, switchboard connection and output against expected — which is what most Australian repairers sell as a fixed-price diagnostic.