- Solar and energy
- Solar inverter
18x37
SolarEdge 18x37 on a solar inverter: AC grid voltage too high
Risk level
Medium
Proceed carefully and stop if the check is unclear.
Urgency
Medium
Quick answer
The inverter measured an AC grid voltage above its protection limit and stops exporting. Note when it happens and consult your grid operator, as SolarEdge advises. Settings and measurements are for the installer.
Safety first
Stop and check this first
- Do not simply ask for the grid protection limits to be raised. SolarEdge only allows changing them if local authorities permit it.
Safe checks you can perform
- Code and message on the inverter screen
- Record of when it appears
- Contact the grid operator
- Grid voltage measured with inverters off
Leave these tasks to a qualified professional
- Do not attempt this professional task: Country setting check
- Do not attempt this professional task: AC grid voltage measurement
- Do not attempt this professional task: AC cable size review
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.
Country setting check
What they doThe installer checks in the inverter that the selected country and grid match the installation.
They must show youthe screen with the configured country.
In writingthe correct country and any change made.
AC grid voltage measurement
What they doWith the inverters off, they measure the AC grid voltage at the connection point.
They must show youthe measured value against the country protection limits.
In writingthe reading, where and when it was taken.
AC cable size review
What they doThey check that the output cable size matches the distance between the inverter and the grid connection point, following the SolarEdge wiring application note.
They must show youthe installed cable size and length.
In writingthe calculation and, if replaced, the new cable.
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.
Code and message on the inverter screen
- Who:
- you, with no tools and without opening anything.
- How:
- look at the inverter screen, or SolarEdge monitoring if you have access, and write down the full code.
- Result that matters:
- that it reads 18x37 V-Line Max.
- If it shows 18x37 V-Line Max:
- grid voltage too high is confirmed.
- If it shows 18x38 V-Line Min:
- that is voltage too low, a different error with similar causes.
- Evidence to keep:
- photo of the screen with date and time visible.
Evidence: Appendix A: Errors and Troubleshooting (Single Phase Inverter with HD-Wave Technology Installation Guide, MAN-01-250-1.2)
Record of when it appears
- Who:
- you, with no tools.
- How:
- note the date and time of each occurrence and whether the inverter resumes producing afterwards.
- Result that matters:
- whether the error is a one off or frequent.
- If it is frequent:
- it gives data for the grid operator and the installer.
- If it happened once:
- keep the record and watch whether it returns.
- Evidence to keep:
- list of dates and times.
Evidence: Appendix A: Errors and Troubleshooting (Single Phase Inverter with HD-Wave Technology Installation Guide, MAN-01-250-1.2)
Contact the grid operator
- Who:
- you or your installer.
- How:
- contact your local grid operator, explain the inverter reports high grid voltage and give the dates and times.
- Result that matters:
- whether the grid operator confirms high voltage on your supply.
- If they confirm it:
- the source is the grid and the operator corrects it.
- If they do not:
- the installer checks the country setting and the AC cable.
- Evidence to keep:
- complaint reference number or written reply.
Evidence: Appendix A: Errors and Troubleshooting (Single Phase Inverter with HD-Wave Technology Installation Guide, MAN-01-250-1.2)
Grid voltage measured with inverters off
- Who:
- qualified installer or electrician.
- How:
- turn off the inverters on site and measure the AC grid voltage at the connection.
- Result that matters:
- the measured voltage against the limits for the configured country.
- If it is already high with no production:
- the source is the distribution grid.
- If it is normal with no production:
- it points to the AC cable or the inverter setting.
- Evidence to keep:
- measured value with date, time and measuring point.
Measuring grid voltage means working near live parts. Qualified electrician or installer only.
Evidence: Appendix A: Errors and Troubleshooting (Single Phase Inverter with HD-Wave Technology Installation Guide, MAN-01-250-1.2)
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
- SolarEdge
- Product type
- Solar inverter
Known code variants
- SolarEdge 18x37
- SolarEdge error 18x37 AC voltage too high
- SolarEdge error 18x37 tensión alta
- SolarEdge error 55
- SolarEdge V-Line Max
What it means
SolarEdge defines 18x37 V-Line Max (error 55 on firmware 3.18xx and earlier) as AC voltage too high at the inverter connection. The manufacturer table points to three sources: a wrong country set in the inverter, which fixes the grid protection limits; high voltage on the distribution grid itself; or an AC output cable too thin for the distance to the connection point. The code does not tell them apart, so voltage is measured with the inverters off.
Warnings and stop conditions
- Mediumsource verified
Do not simply ask for the grid protection limits to be raised. SolarEdge only allows changing them if local authorities permit it.
Evidence: Appendix A: Errors and Troubleshooting (Single Phase Inverter with HD-Wave Technology Installation Guide, MAN-01-250-1.2)
Symptoms and causes
Probable causes · in order
- Wrong country set in the inverterPossible
The selected country sets the grid protection limits. It is ruled out by checking the country setting matches your installation.
Evidence: Appendix A: Errors and Troubleshooting (Single Phase Inverter with HD-Wave Technology Installation Guide, MAN-01-250-1.2)
- High voltage on the distribution gridPossible
If grid voltage is already high with the inverters off, the source is outside your installation and the grid operator assesses it.
Evidence: Appendix A: Errors and Troubleshooting (Single Phase Inverter with HD-Wave Technology Installation Guide, MAN-01-250-1.2)
- AC cable too thin for the distancePossible
When the inverter is far from the connection point, a small cable raises the voltage the inverter sees. SolarEdge recommends a larger gauge cable.
Evidence: Appendix A: Errors and Troubleshooting (Single Phase Inverter with HD-Wave Technology Installation Guide, MAN-01-250-1.2)
Virtual technician
Does 18x37 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
SolarEdge Technologies · manual
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