Thanks @mfalkvidd
Yes, I have been down that route as well - stitching my meter together from other sensors already known by mysensors.
I had a look at eg S_WIND, where the sensors can have 3 values, with one of them even in a completely different domain (V_DIRECTION)
So ideally mysensors supported my energy meter as a "thing" with the relevant set of parameters.
Question is if I should add a custom type to mysensors myself, does it support "local" additions? What would be the "correct" way to do it?
Soon I might have all kinds of sensors which has never been in the scope of mysensors, and probably should never be either, like meals served in the canteen, cars in the parking lot and so on.
mysensors appears to have some really cool communication implemented, I can just not fit into the types defined.
I have found that simply setting type using something like msg.setType(99); give me full control, but it is of-course just another hack.