SMA Neither an extension nor a replacement is possible in this device class

I was requested to help debug an SMA installation:

You might have gotten the “ Neither an extension nor a replacement is possible in this device class “ on your sunnyportal after plugging a second inverter over speedwire to your sunny home manager 2.0

I’m making this post as even SMA help couldn’t solve the issue: the sunny home manager cannot operate more than one battery inverter, no matter the type, no matter the connection. It will not be able to operate a SMA tripower with an SMA SBS, or other combinations.

If you plug two battery inverters in, the second one will use the home manager to measure the grid input/output and will oscillate with the already included battery inverter. The only way could be to use modbus commands and a separate piece of code.

Their website doesn’t specify this clearly. I only did this as a test to help troubleshoot, as we only use one inverter with battery regularly.

Hope this helps. If you have a used, damaged or broken inverter or battery, do not hesitate to reach out.