CMS 5000-Grid Fault Message

  • Energy bill higher than usual?


  • Installer gone broke?


  • Out of manufacturer’s warranty by just a few months?



Although the CMS Solar Inverter is known to have a few problems, once fixed they should perform admirably. However, CMS has been in receivership and therefore, no warranty exists for their products.

Andrew noticed an issue with his inverter when he received his electricity bill for the quarter. Instead of having a credit amount on his bill, Andrew now owed a large sum of money to the energy company. . Error message on display screen read “GRID FAIL”, which is not a common error.

Whilst on site, ACE performed initial diagnostics. AC and DC power supplies were both okay with no leaking cracks, no burnt components or cracked moffets. There was a burnt smell and two blown 240-volt ceramic fuses.

The report we gave our offsite solar engineer was unable to give confirmation of a complete repair. We supplied Andrew with new inverter quotes and a quote to replace two DC isolators with new heavy duty switch style isolators, as the existing ones are non-compliant. Due to the unknown of where the fault actually lies, we need to perform a diagnostic test in most circumstances.

If your CMS 5000 solar inverter is displaying the Grid Fault message, then there is a software fault where the grid’s measured data in voltage and frequency are above the required specifications.

Trouble Shooting Tips


Below are some suggested solutions to your CMS 5000 Solar Inverter Grid Fault problem:

  1. Log into the CMS inverter with a software device.
  2. Modify the grid parameters.

Please note that these are general tips only and are based on our current and past experience and therefore, not specific to your solar inverter problem. What we usually find is people trying these troubleshooting tips and if these fail, they give us a call and we can perform diagnostic tests. What we usually find is people trying these troubleshooting tips and if these fail, they give us a call and we can perform diagnostic tests and provide a solution.


  • 50% of the time it’s a quick easy fix for any solar tech…
  • Error messages and fault codes that are due to an external fault elsewhere in the solar system.
  • The solar system is tricking the inverter into thinking it has that error or fault.
  • External faults are relatively easy to find and repair. Once fault is repaired, the inverter is back online.
  • Other 50% of the time
  • There is a fault, which requires more diagnostic type of testing to locate the fault. Out of these about 1 in 4 can be solved onsite. Things like a dodgy install or water damage somewhere.
  • The rest of the time it’s the inverter that’s the problem. 1 out of every 2 times the inverter can be sent away for repairs or we can organise those repairs under warranty with the manufacturer, and…
  • The rest of the time the inverter was of low quality and either not fixable of not good value to fix. If this is the case we would quote on an inverter with similar specs to replace it with. Getting your system back online fast with high quality parts.
  • In the worst case scenario, rare ground leakage faults are very difficult to find and fix but we have also had experience locating these aswell.
Be careful some dodgy solar guys will just say you need a new inverter without performing any tests just so they can sell you a new inverter that you may not even need!
Nevertheless, we can help you with any solar problem you may have. Call us on 1300 796 500!


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