Warning What does this mean?
Your system is down or running degraded, but this is not an immediate safety danger. Work through the safe steps below.
Huawei Inverter Alarm 2035 — What Causes Unbalanced Grid Voltage?
Alarm 2035 means the difference between your three grid phase voltages has exceeded the inverter's upper threshold — the phases are out of balance with each other. This is almost always a grid-side condition rather than an inverter fault: uneven loads, a weak neutral connection, or heavy single-phase demand nearby. The SUN2000 stops feeding in and recovers automatically once the phases come back into balance. If it happens frequently, the fix involves your installer and usually your local power operator, not the inverter.
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
On a three-phase supply, the three phase voltages should sit close together — in a 400 V system, all three phases should read roughly 230 V each to neutral. Alarm 2035, "Unbalanced Grid Voltage," fires when the spread between the highest and lowest phase voltage grows beyond the protection threshold Huawei sets for the local grid code. In plain terms: one phase is sagging while another is floating high, or one phase is being pulled around by something on the network.
This is a Major alarm in Huawei's classification, but "Major" here describes how the inverter responds, not how dangerous it is to you. The SUN2000 disconnects its output to protect itself and your home from feeding into — or drawing from — a distorted supply, then watches the grid and reconnects on its own when the phases settle back into balance. The inverter is behaving exactly as designed; it is the messenger, and shooting it (by replacing the unit or resetting everything) won't change the message. Persistent imbalance lives upstream of your inverter: in the street's distribution, in your building's wiring, or in how loads are spread across the three phases.
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
- Uneven loading across the three phases — for example, most of a building's heavy single-phase loads (heaters, EV chargers, air conditioning) sitting on one phase.
- A loose, corroded, or undersized neutral conductor in the building wiring or the utility service, which lets the phase voltages drift apart under load.
- High solar export on one phase in the neighborhood pushing that phase's voltage up while the others sit lower.
- Utility-side issues: a failing distribution transformer tap, a broken conductor, or switching work on the local network.
- A loose AC terminal or breaker in your own switchboard affecting one phase leg to the inverter.
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 a professional if the alarm recurs regularly — weekly or daily — or if generation losses are becoming significant. Your installer should verify the AC cable terminations and measure the phase voltages at the inverter; if the imbalance is confirmed upstream, the next call is to your local power operator, who is responsible for supply quality. Huawei's own troubleshooting says exactly this: frequent occurrences mean checking whether the grid voltage is within the acceptable range, and contacting the local power operator if it is not. Any work inside the switchboard, on terminals, or on the service connection is electrician-only. If you ever see flickering lights across the house alongside the alarm, treat it as a wiring-integrity concern and get an electrician promptly.
Frequently asked questions
Will alarm 2035 clear on its own?
Usually, yes. If the imbalance is temporary — a passing load, network switching, a hot afternoon of solar export — the SUN2000 detects the phases returning to balance and reconnects automatically. Only recurring alarms need investigation.
Is my inverter broken?
Almost certainly not. Unbalanced grid voltage is a supply-side condition, and the inverter is doing its protection job by disconnecting. Replacing the inverter would not fix a phase imbalance coming from the street or the switchboard.
Can I see which phase is the problem?
Yes — the FusionSolar app shows per-phase voltage. Look at the readings logged around the alarm time: the outlier phase is the one drifting. Hand those readings to your installer; they save a lot of diagnostic time.
Should the protection threshold be adjusted to stop the nuisance tripping?
Only your installer can do this, only through the app, SmartLogger, or NMS, and only with the consent of the local power operator. Widening protection thresholds without approval can breach your grid-connection agreement.
Why does it happen more on some days than others?
Imbalance follows load and generation patterns. Hot evenings with air conditioning on one phase, or sunny middays with heavy single-phase solar export in the street, are classic triggers.
Need a professional?
This fault may need professional diagnosis. Contact a qualified solar electrician in your area.
Sources: meaning and troubleshooting verified against the manufacturer's documentation — SUN2000-(8KTL, 10KTL, 12KTL, 15KTL, 17KTL, 20KTL)-M0 User Manual, Issue 03 (2019-07-19), Section 7 Maintenance — Alarm 2035 'Unbalanced Grid Voltage', Major: 'The difference between grid phase voltages exceeds the upper threshold' (solar.huawei.com).