Solis UN-G-F: Grid Under Frequency
UN-G-F (under grid frequency, code 1013) is the mirror image of OV-G-F: the grid frequency dropped below the allowed range, so the Solis disconnected to follow grid-protection rules. Frequency is the utility's job, so UN-G-F is almost always a grid-side event that clears by itself once the grid recovers.
What usually causes UN-G-F
- A short grid frequency dip on the utility side.
- A weak or overloaded grid, where frequency sags under heavy demand.
- Running off a generator that bogs down under load.
How to handle it
- Wait for it to clear. The inverter reconnects automatically once the frequency is back in range. A brief, occasional UN-G-F is normal.
- Notice the frequency. Rare is fine; frequent UN-G-F suggests an unstable or overloaded supply.
- On a generator, make sure it is not overloaded and is tuned for stable output.
- For persistent UN-G-F, contact your installer or utility about grid stability.
Related Solis codes
FAQ
Why do OV-G-F and UN-G-F both show up sometimes?
An unstable grid can swing both above and below the frequency limits, so you may see both over-frequency (OV-G-F) and under-frequency (UN-G-F) on a shaky supply.
Helpful guides
Sources
- Solis inverter alarm-code list (UN-G-F = grid frequency below the limit; verify grid connection and standard setting).
- Solis installer documentation.
⚠️ Safety disclaimer. Solar inverters carry lethal DC and AC voltage even when "off". This guide covers observation only. Grid and generator issues should be handled by your installer, utility, or a qualified technician.