Solis UN-G-V: Grid Undervoltage
UN-G-V (under grid voltage, code 1011) is the mirror image of OV-G-V: the grid voltage the Solis measures has dropped below the allowed range, so it disconnects to protect itself and the grid. This is usually a grid-side event like a brownout or a weak supply, and the inverter reconnects on its own once the voltage is back to normal.
Grid, your wiring, or the inverter?
- A brownout or weak grid. The utility voltage genuinely sagged. Most common, and it self-corrects.
- Voltage drop on a long or thin AC cable, which can pull the reading low under load.
- A loose AC connection adding resistance.
How to handle it
- Wait for it to clear. If the grid voltage was just low for a while, UN-G-V clears by itself when it recovers. A brief, occasional one is normal on weaker grids.
- Notice how often it happens. Rare and brief is fine. Frequent or long UN-G-V events point to a genuinely weak supply or a wiring issue.
- Check for obvious causes. If your whole area has low or unstable power, it is the utility. If only your system reads low, the AC cabling may be the cause.
- For persistent UN-G-V, call your installer to check the AC cable and connections, or contact your utility about the supply voltage.
Related Solis codes
FAQ
UN-G-V happens a lot in the evening.
Evening demand can pull neighbourhood voltage down. If it is frequent, mention it to your installer and utility, since a chronically low supply is not ideal for the system.
Helpful guides
Sources
- Solis inverter alarm-code list (UN-G-V = grid voltage below threshold; verify grid connection and voltage, confirm standard setting).
- Solis installer documentation.
⚠️ Safety disclaimer. Solar inverters carry lethal DC and AC voltage even when "off". This guide covers observation only. AC cabling and connection checks must be done by a licensed installer or electrician.