Solar inverter tripping on high grid voltage? What it means
If your solar curve has a hole in the middle of a sunny day (output falls straight to zero, then climbs back a few minutes later), the panels are rarely the problem. Most often the inverter has disconnected because the grid voltage at your meter went too high.
Why the voltage goes up
Your inverter can only push power out if its voltage is slightly higher than the grid's. On a street where many homes have solar, everyone exports at once around noon and the local voltage rises. A transformer set on a high tap, or a long or thin cable between the inverter and the meter, adds to it.
The limits an inverter works to
Many inverters ship with the limits from IEC 61727, the standard for grid-connected solar:
| Limit on a 230 V supply | |
|---|---|
| High voltage | 110% → 253 V |
| Low voltage | 85% → 195.5 V |
| Frequency | nominal ±1 Hz |
Go past them and the inverter must stop exporting, then wait for the grid to settle before it reconnects. Some inverters first cut their output back before they trip. Installers often widen the limits within what the utility allows, so yours may run on above 253 V. The settings menu or the installer's commissioning sheet shows the real values.
How to tell if it's happening to you
- The dips happen on clear days around midday, not on cloudy ones.
- The inverter's display or app shows a grid over-voltage or AC voltage high fault.
- Grid voltage readings sit close to the high limit just before each stop.
Helio checks this for you. Its grid check plots the day's grid voltage against the limits, counts how long it spent above them, and marks a stop as a likely high-voltage trip when the voltage was within 3 V of the limit just before. When the voltage goes high but the inverter keeps running, it says that too, so you know your limits have been widened.
What to do about it
- Collect evidence. A week of daily minimum and maximum grid voltage is far more convincing than "it keeps switching off". Helio's export includes both for every day, with the time of the peak.
- Ask your installer to check the AC cable size and length between the inverter and the meter, and the inverter's voltage settings against what your utility allows.
- Complain to the utility with those readings if the voltage is high even when your system is off. A transformer tap change is their job, not yours.
Don't change grid protection settings yourself. They exist so that line workers are safe when the grid is down.
See the grid check on the demo roof or read how many units a system should make per day.
Questions
Why does my solar inverter switch off at noon?
On a sunny day the most likely cause is high grid voltage. When the voltage at your meter goes above the inverter's limit, it must disconnect for safety, then waits and reconnects. It looks like a sharp drop to zero in the middle of the day's curve.
What grid voltage is too high for a solar inverter?
Many inverters ship with limits from IEC 61727: 85% to 110% of nominal, which is 195.5 V to 253 V on a 230 V supply. Installers sometimes widen these within what the local utility allows, so check your inverter's settings.
Can I just raise the inverter's voltage limit?
Not on your own. The limits are a safety and grid-code setting, often approved by the utility at connection. Ask your installer, who can check what is allowed in your area.
Does high voltage damage solar panels?
The panels aren't affected; they sit on the DC side. The inverter protects itself and the grid by disconnecting. The cost is the units you lose while it is off.
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