Solar inverter dead, blank, or showing a fault
The rooftop solar has stopped generating — the inverter display is blank, or it's alive but sitting on a fault code. The owner usually notices when the power bill jumps.
Safety first
PV strings are LIVE whenever there's daylight — the DC side doesn't switch off with the sun up, and DC arcs don't self-extinguish. Never open DC isolators under load or open string wiring live. In Australia, work on the PV (DC) side is for accredited/appropriately competent people; the AC side to the board is ordinary licensed work. Isolate in the sequence the shutdown procedure label gives.
Isolate, lock out / tag out, and prove dead before working unless a live test is specifically required, authorised, and carried out under proper supervision. Always follow local regulations, your site procedures, and the equipment manufacturer's documentation.
Apprentice mode
Full walk-through — the why, what readings mean, mistakes & safety.
Likely causes
Ranked from most to least likely.
- 1
AC supply to the inverter lost
Most likelyThe dedicated solar breaker/main switch at the board is off or tripped, or an upstream RCD has taken it out. An inverter with no grid reference shuts down (anti-islanding) — many models also go completely blank without AC.
- 2
DC isolator failed or switched off
#2Rooftop and wall DC isolators are a notorious weak point — water ingress, heat damage, or simply left off after roof work. No DC in, nothing to convert.
- 3
Grid outage or voltage/frequency outside limits
#3The inverter is healthy but disconnected itself because the grid is out or outside its programmed window — it reconnects by itself once conditions return.
- 4
Inverter internal failure
#4Electrolytics, relays and boards do die — especially in units mounted in full sun. Both supplies present with a dead display points here.
- 5
A specific fault code doing its job
Least likelyIsolation faults, earth faults and arc-fault detections deliberately stop generation — the code on the display (or app) is the diagnosis, so read it before pulling anything apart.
Reports are saved on this device to reflect what you actually find.
Testing sequence
Work through one test at a time. Expected reading and what each result means.
On the tools? Job Mode shows one test at a time with thumb-sized buttons — your place and readings carry straight over.
Enter Job ModeRead before you touch: note any display/LED state or app fault code, and photograph it. Then check the dedicated solar breaker and any RCD at the switchboard.
Either a meaningful fault code, or a tripped/off solar breaker staring at you.
A fault code directs the rest of the job (isolation fault → its own guide). A tripped breaker: find out why before simply resetting.
No code, breaker on — verify the AC supply actually reaches the inverter next.
View all expected readings at once
Fault-finding flowchart
The same logic as a decision tree.
- 1start
Solar inverter dead or on a fault
→ step 2 - 2decision
Is there a fault code on the display or app?
Yes→ step 3No→ step 4 - 3result
The code IS the diagnosis — follow it (isolation fault has its own guide).
- 4decision
Solar breaker on and AC present at the inverter?
Yes→ step 5No→ step 6 - 5decision
DC isolators on, healthy, and string voltage present in daylight?
Yes→ step 7No→ step 8 - 6result
AC supply fault — find why the breaker/RCD is out or trace the run to the inverter.
- 7result
Both supplies present + dead unit = inverter failure. Manufacturer/installer job.
- 8result
DC-side fault (isolator, connector, string) — accredited solar diagnosis, no live DC work.
Common mistakes apprentices make
- Cycling isolators in random order under full sun — follow the labelled shutdown/startup sequence.
- Resetting a tripped solar breaker or RCD without asking what tripped it.
- Blaming the inverter without checking the humble AC breaker first — it's the most common 'fault'.
- Ignoring the fault code and app history, which often names the problem outright.
When to stop & escalate
String/rooftop DC faults, isolation faults and anything requiring panels or DC wiring to be opened belong with an accredited solar electrician. Inverter internal failures are manufacturer-warranty jobs — don't open the unit. If it disconnected on grid limits repeatedly, see the grid-overvoltage guide.
If you're past your competence, authorisation, or the safe limits of the job — stop and hand it on. There's no fault worth getting hurt over.
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Related faults
Solar inverter shutting down or derating on grid overvoltage
The inverter runs, then backs off or disconnects through the middle of the day with overvoltage events in its log. Generation (and the feed-in credit) suffers — worst on bright days when everyone's exporting.
Solar inverter showing an isolation / earth fault (often after rain)
The inverter refuses to start (or shuts down) on an isolation, ISO, ground-fault or Riso error — classically first thing on a dewy morning or after rain, sometimes clearing as the day dries out. Something on the DC side is leaking to earth.
A circuit breaker keeps tripping (domestic)
One circuit breaker keeps tripping — instantly on reset or after a load runs — and you need to tell an overload from a short or a faulty appliance.
No power to the whole house
The entire home has no power — nothing works. Could be a supply outage, the main switch/main safety switch, or a main fault, and the first job is to tell which.