Critical What does this mean?
A safety-rated fault — there may be a risk of electric shock, fire, or equipment damage. Do not try to fix this yourself. Call a qualified electrician.
Solis Inverter Ground-Fault — What the 1033H Alarm Means for You
When your Solis shows a GROUND-FAULT alarm (code 1033H), it has detected current leaking from the DC (solar panel) side of your system to earth — and it has disconnected itself from the grid to protect your equipment. This is one of the more serious alarms a Solis can raise: a damaged cable or a poorly sealed connector somewhere in your array is touching ground. Do not keep restarting the inverter to clear it. Note the alarm code, leave the system safely off, and call your installer — they will trace the faulty string with voltage-to-ground and insulation tests.
What should I do first?
Two quick questions — we'll point you to the right starting point.
Is this code still showing on your inverter's display?
Is your system producing power right now?
What this code means
Your panels operate at several hundred volts DC, and every part of that circuit is supposed to be fully isolated from earth. A ground fault means that isolation has broken down somewhere: a live conductor is making contact with the panel frames, the mounting rails, or the ground itself. Because Solis inverters are transformerless, a DC ground fault can drive current through paths that were never designed to carry it — which is why Solis’s own seminar material calls ground faults relatively common but unusually damaging to inverter equipment.
Its insulation monitoring watches continuously. The moment it detects the leak, it raises the GROUND-FAULT alarm, logs code 1033H, and disconnects from the grid until the fault is eliminated — a deliberate refusal, since re-energising a grounded array risks arcing, equipment damage, and fire.
Where do these faults come from? Solis’s troubleshooting seminar names three classic sources: the insulation on a panel’s DC cable gets damaged and touches the metal mounting bracket; an MC4 connector in the string is poorly sealed so moisture bridges it to the bracket; or the DC cable running from the string to the inverter has damaged insulation reaching ground. Age, UV, rodents, wind abrasion, and sloppy original workmanship all feed the same three.
What is this downtime costing you?
Rough estimate while your system isn't producing. Adjust the numbers to match your setup.
≈ – kWh of lost production per day.
Estimate only — assumes ~80% real-world output vs. nameplate. Actual losses depend on weather, shading, panel direction, and your tariff.
Common causes
- Damaged insulation on a panel’s DC cable within the string, letting the conductor touch the metal mounting bracket — the most common cause in Solis’s seminar.
- A poorly sealed MC4 connector in the string, where moisture ingress creates a conductive path to the bracket or frame.
- Damaged insulation on the DC homerun cable between the string and the inverter, contacting ground along its route.
- Long-term weathering — UV degradation, wind abrasion, or rodent damage exposing conductors over the years.
- Water ingress after heavy rain — moisture doesn’t usually create a fault in healthy cabling, but it reliably exposes insulation that was already marginal, which is why ground faults often appear in wet weather.
Safe steps to try
Work top to bottom, ticking off each step as you complete it. 0 of 5 done.
Is your inverter still under warranty?
Before paying for a repair, check — your installer may fix this free.
Based on typical standard warranty terms — always confirm with your warranty card or installer paperwork, as terms vary by model, region, and purchase date.
When to call an electrician
Call your installer immediately — a ground fault is not a wait-and-see alarm. The inverter has already done the only safe thing it can (disconnect); everything after that is fault-finding on a live DC array, which Solis’s own documentation frames as work for trained people: the official troubleshooting method is to disconnect each string’s DC switch and measure PV+ to ground and PV− to ground with a meter. A healthy string reads roughly 100–1000 V to ground, decaying below 20 V during the measurement; a grounded string shows one polarity near 0 V and the other above 600 V and steady. Your technician will also verify insulation resistance. If you smell burning, see scorch marks, or the alarm followed a lightning strike, say so on the call — and if there is any sign of arcing or smoke, treat it as an emergency, keep clear, and call emergency services.
Frequently asked questions
Why won’t the inverter reconnect by itself?
Because the fault hasn’t gone away. The inverter disconnects from the grid as protection and stays off until the ground fault is physically eliminated — no amount of restarting fixes a damaged cable.
The fault appeared after heavy rain. Is that a coincidence?
Almost certainly not. Moisture is the classic revealer of damaged insulation — a cable that tests fine when dry can leak to ground as soon as water bridges the damaged spot. Wet-weather ground faults are a textbook pattern.
What does the “above 2 MΩ” insulation figure mean?
It’s the pass mark for the array’s insulation resistance test. Above 2 megohms the insulation is sound; below it, the cable or connector under test is leaking and needs repair or replacement.
Can a ground fault cause a fire?
It can, if ignored — current flowing through unintended paths generates heat, and damaged DC conductors can arc. That’s precisely why the inverter disconnects and why you shouldn’t keep forcing it back on.
Need a professional?
This fault is a safety risk — do not attempt to fix it yourself. Contact a qualified solar electrician in your area.
Sources: meaning and troubleshooting verified against the manufacturer's documentation — Solis Seminar Episode 39, “How to Quickly and Effectively Determine Ground Fault” (solisinverters.com) — “inverter will display a GROUND-FAULT alarm when it starts running, and the alarm code is 1033H. At the same time, it will disconnect from the grid until the fault is eliminated”; causes: damaged DC cable insulation touching the metal bracket, poorly sealed MC4 connector, damaged string-to-inverter DC cable; troubleshooting: disconnect each string’s DC switch and measure PV+ / PV− to ground (healthy: 100–1000 V decaying below 20 V; faulty: one polarity ~0 V, the other >600 V and steady). Solis Seminar Episode 55 — insulation resistance testing; healthy insulation above 2 MΩ.