Understanding energy consumption

[tyfoon]

I have 4x MHI srk20 zm-s (4 rooms) with 2x SCM40ZM-S (so 2 inside units on 1 outside units).

Two questions:
a) Can someone explain what the energy sensor exactly report? Is there some form of double counting or is the sum of the 4 ESP units also the real sum of the daily energy consumption?

b) 2 of the 4 units report a significant higher 'standby' use then the other 2. Up to 300w per day while they are totally off. See the graphs below. Does anyone have an explanation for that? The sensors show no pump or fan activity in all cases.

Thanks

AC Power (comparing the 2 to show the different behavior):

AC Energy (all overlayed):