If your libbi displays Code 155 / W04: Solar Loss, the libbi has detected that Solar PV has been connected, but no Solar Generation is being produced.
What does this mean?
Your libbi expects to receive power input from the connected solar PV system. When the system detects that the PV input is inactive or producing zero energy, Code 155 / W04: Solar Loss, will be displayed. This could occur due to several reasons such as, night-time, low light conditions or disconnected PV system.
This is not normally a fault but can occur on libbi with no solar being connected.