Hi

I have two RCT MKII inverters configured in parallel and recently experienced an issue. Following the repair, the inverters are no longer operating in parallel. I suspect this may be related to firmware.

Could you please advise if someone can assist with providing the latest firmware file or support with resolving this issue?

Regards

On 2026/04/10 at 9:35 PM, Ruan jansen said:

Following the repair, the inverters are no longer operating in parallel. I suspect this may be related to firmware.

My guess is that they replaced the control board with one that has different firmware.

Please report the main (U1) firmware versions for both inverters. Your monitoring software (e.g. Solar Assistant, but there are many others) may be able to provide this, or you could use the up or down buttons near the display until you get a display starting with "U1". Report the next four digits.

Edit: Other possibilities include that the paralleling board was not replaced, or one of its cables. Or that you haven't connected the paralleling cables properly, or a pin became damaged with the un- or re-plugging, etc. Also check setting 16, output mode. It should be PAR for paralleling.

Do you see HS and SL on the two inverters? These indicate MaSter and SLave.

Edited April 13Apr 13 by Coulomb