How to Solve Error 09 in Off Grid Conversol Inverters

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How to Solve Error 09 in Off Grid Conversol Inverters

Error Code 09 and how to prevent it

The inverters have internal overvoltage protection but the actual protective devices have also their absolute maximum limit.

In most cases, if the Inverter’s IGBT or DC-DC MOSFET are damaged then the inverter always reports the Error 09 alarm. The inverter converter the DC power to pure AC sinewave . Hence, DC-DC MOFSET and Inverter IGBT are also frequent failure components. It could be due to the high AC surge or PV surge to damage these sections. To avoid such problem, we would also recommend installing the external SPD for PV input and AC input.

Adding surge protection devices will reduce the risk of getting 09 error.  If your installation is protected by surges in voltage then your warranty will not be invalidated.

The best practise in electrical installations is to install the SPD’s in a PV DC-Combiner box (between solar panels and inverter DC input) and a single phase or three phase SPD at the AC-output of the inverter. The latter is usually part of the consumer unit and requires only 2 positions in the enclosure. It is important to mention that all surge protection devices must be earthed following the wiring insructions.

You can purchase the right combiner box online, before you do that check the max PV voltage of your inverter and the manufacturer will install the correct SPD devide. There are 3 voltage categories for off grid inverter: 100Vdc, 145v and 500V.

Error description in the manual: Bus Soft Start Failed.


When the error appears you have to return the inverter to the manufacturer. If the main board is beyond repair, then a brand new inverter-board will be installed.