That “clip” appear to be a YHDC split core c.t, from the same family as our standard one.
Reading the installation instructions, the only way I can think that your device might work is, it transmits an analogue replica of the current wave to the control box, and the relative phase of voltage and current are compared there, hence the direction of power flow can be inferred. I would imagine that, to have a decent battery life, that cannot be done continuously (as the diverters published here do) but it must be done on a sampling basis - maybe for only a few mains cycles every half-minute or something like that.