SolarEdge AC Voltage Too High or Too Low: Grid Voltage Errors Explained

If your SolarEdge inverter is showing AC voltage errors (codes 18x37 for high voltage or 18x38 for low voltage), the problem usually isn't your solar system — it's the electrical grid your system connects to.

What's Happening?

Your solar inverter must match the grid's voltage and frequency to safely export power. If the grid voltage drifts too high or too low, the inverter shuts down as a safety measure. This protects both your system and the grid.

Think of it like trying to merge onto a highway — if traffic is moving too fast or too slow, you can't safely merge.

Common Causes of High Grid Voltage

Too much solar in your neighborhood. When many homes on the same transformer have solar systems all producing at peak, the local grid voltage rises. This is especially common in sunny suburban neighborhoods.

Long distance from the transformer. Homes at the end of a power line run often experience higher voltage fluctuations.

Utility voltage set too high. Some utilities maintain higher-than-normal voltage to compensate for long distribution lines.

What You Can Do

1. Report it to your utility. They may need to adjust the local transformer or voltage settings.
2. Check your inverter's country settings. Make sure the grid protection parameters match your local utility's specifications.
3. A qualified installer may be able to adjust the voltage trip points within permitted ranges (with utility approval).

These errors can be frustrating because they're often outside your control. But knowing when they happen — and how much production you're losing — gives you the leverage to work with your utility to resolve the issue. SolarDoctor's health score tracking makes that impact visible.