- Solar and energy
- Solar inverter
UN-G-V
Solis UN-G-V on a solar inverter: grid voltage too low
Risk level
Medium
Proceed carefully and stop if the check is unclear.
Urgency
Medium
Quick answer
The Solis inverter sees grid voltage below its protection value (UN-G-V, alarm 1011) and stops feeding in. If it is occasional, it recovers by itself once the grid is normal. If it repeats every day, keep the history and tell your installer.
Safety first
Stop and check this first
- Do not open the AC connector or the board: checking wiring and measuring grid voltage is the installer's job.
- Protection limits are only changed with the electricity company's consent, as the Solis manual states.
Safe checks you can perform
- Alarm in the app or on the display
- How many times a day it appears
- Visible state of the AC breaker
Leave these tasks to a qualified professional
- Do not attempt this professional task: AC connector and wire sequence check
- Do not attempt this professional task: Grid standard and protection points
- Do not attempt this professional task: Displayed voltage versus voltage at the AC gland
What a technician must be able to justify
Technician visit
These are the steps they must carry out and show you. Tick them as they work: if steps are skipped, do not accept a part swap.
These are not instructions for opening or handling the equipment yourself. They are the checks that should support a technical conclusion.
AC connector and wire sequence check
What they doChecks all AC side connections, especially the AC connector, the wire sequence inside it and any loose contacts.
They must show youphotos of the AC connector and board before and after.
In writingwhat was corrected and the generation test afterwards.
Grid standard and protection points
What they doVerifies the grid standard and, if the grid is out of range with correct wiring, asks Solis to modify the protection points with the electricity company's consent.
They must show youthe configured grid standard and the alarm history.
In writingthe standard chosen, any value changed and the company's authorisation.
Displayed voltage versus voltage at the AC gland
What they doThe installer compares the voltages the inverter displays with those measured at the AC connector: phase to neutral, phase to earth and neutral to earth on single phase.
They must show youthe voltages on the display and those measured at the AC connector.
In writingthe measured values and where they were taken.
Before accepting a part or repair
Nothing has been shown yet. Do not accept a part swap based on the code alone.
Follow these steps
Note: Follow the documented order. An error code identifies the affected system, but it does not prove by itself which part has failed.
Alarm in the app or on the display
- Who:
- you, with no tools.
- How:
- in the app open the Alarm page, which shows the message, code and solving methods; on models with an LCD, go to Advanced Information with code 0010 and open Alarm Message, as Solis describes.
- Result that matters:
- confirming the alarm is UN-G-V (code 1011) and seeing its times.
- If it appears now and then:
- Solis says it may be a short grid abnormality and the inverter resumes by itself.
- If it repeats often:
- keep the times and move on to the next checks.
- Evidence to keep:
- a screenshot or photo of the alarm with date and time.
Evidence: User Manual for S6 Series Grid Inverter Version 1.1, Release Date: 04,2024 · How do I get to the alarm messages?
How many times a day it appears
- Who:
- you, reviewing the alarm history.
- How:
- count how many times the alarm shows each day and at what times. Solis service separates once or twice a day, which it attributes to an unstable grid, from a continuous error, which needs checking.
- Result that matters:
- knowing whether it is a brief grid issue or a continuous fault.
- If it shows once or twice a day:
- note the times; it is usually the grid and the inverter recovers by itself.
- If it is continuous or the inverter barely generates:
- tell the installer and share the history.
- Evidence to keep:
- the daily count and times of the alarm over several days.
Evidence: 1011 - UN-G-V
Visible state of the AC breaker
- Who:
- you, looking at the board without opening covers or touching wires.
- How:
- find the inverter AC breaker and check whether it is on. Solis asks for a check that the AC side breaker and output cable are connected properly; you only look at its position.
- Result that matters:
- ruling out a breaker that is off or keeps tripping.
- If it is on:
- checking wiring and voltage is the installer's job.
- If it is off or keeps tripping:
- do not reset it again and again; call the installer.
- Evidence to keep:
- a photo of the board showing the breaker position.
Evidence: User Manual for S6 Series Grid Inverter Version 1.1, Release Date: 04,2024
Still not solved
If the error persists, stop here. See what the technician must do and show you.
Where this code applies
A code is meaningful only inside the right product and version context.
Primary scope
- System
- Solar and energy
- Brand
- Solis (Ginlong)
- Product type
- Solar inverter
Known code variants
- Solis alarm 1011
- Solis alarma 1011
- Solis Grid Under Voltage
- Solis low grid voltage
- Solis subtensión de red
- Solis tensión de red baja
- Solis UN-G-V
- Solis UN-G-V01
- Solis UN-G-V02
- Solis under grid voltage
What it means
Solis defines UN-G-V (Grid Under Voltage 01 and 02, alarm 1011) as grid voltage below the protective value set in the inverter according to the local grid standard. The S6 manual says that if it occurs by accident it is a short grid abnormality and the inverter resumes with no manual intervention. If it is frequent, Solis service checks the AC connector connection, the wire sequence, loose contacts, the voltage at the AC gland and the selected grid standard. The code alone never proves that a part of the inverter is faulty.
Warnings and stop conditions
- Mediumeditorial warning
Do not open the AC connector or the board: checking wiring and measuring grid voltage is the installer's job.
Evidence: 1011 - UN-G-V
- Lowsource verified
Protection limits are only changed with the electricity company's consent, as the Solis manual states.
Evidence: User Manual for S6 Series Grid Inverter Version 1.1, Release Date: 04,2024
Symptoms and causes
Probable causes · in order
- Unstable or low grid voltageCommon
If it shows once or twice a day, Solis service attributes it to an unstable grid; the inverter resumes once it detects a normal grid.
Evidence: User Manual for S6 Series Grid Inverter Version 1.1, Release Date: 04,2024 · 1011 - UN-G-V
- AC connection wrong or loosePossible
On new installations, Solis asks for checks that the AC cable is properly connected in the connector and in the right sequence, and for loose contacts.
Evidence: 1011 - UN-G-V
- Wrong grid standard selectedPossible
If the grid standard does not match, the undervoltage threshold does not fit the local grid. Solis asks for the right standard to be selected with the grid turned off.
Evidence: 1011 - UN-G-V
Virtual technician
Does UN-G-V still appear after these checks?
Answer a few questions to narrow down the likely cause and the safest next action. Guidance only - it never replaces a professional.
Sources and technical references
- 1
User Manual for S6 Series Grid Inverter Version 1.1, Release Date: 04,2024
Ginlong (Ningbo) Technologies Co., Ltd. (Solis) · 2024 · manual
- 2
How do I get to the alarm messages?
Ginlong (Ningbo) Technologies Co., Ltd. (Solis Service Center) · 2025 · official_doc
- 3
Ginlong (Ningbo) Technologies Co., Ltd. (Solis Service Center) · 2025 · official_doc
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