Hey @mander, currently, the device has to have the capability of incrementing a Watt counter (since kWh is energy usage and W is consumption over time). Some device developers will build this into their device and you can reset the W counter through the device whenever you’d like. However, I have one of these devices and have noticed that I can’t seem to reliably get power consumption from it as events. Device Apps that are capable of counting Ws often don’t send these as events on the ST network, however, you could certainly find some energy meter device code and see if you could modify it to do so!
This is a great idea for an expression inside Initial State though, some way to define a formula for producing a W signal when given a kWh signal over time. Currently, you can define your own equations inside the expressions feature, but this kind of equation would be better suited to have a helper expression because of the time component.