It would be great if devices like lights and smart switches had a few optional attributes concerning power usage, like their standby and maximum/on power, so that their power usage can be tracked “automagically”.
Right now Im trying to do this manually; for each light/room I am making a template sensor that calculates power usage based on state and brightness, then an integration sensor which I then want to add as individual devices in the energy panel. My goal is to eventually have the combined consumption of all my individual devices match my actual measured power consumption, even using dummy sensors for dumb devices. Or get as close as possible.
The above manual approach kinda works (it doesnt for some template sensors, but thats for another topic), but its a lot of work if you have as many smart bulbs and smart plugs as me.
Ideally this would as simple as for each light or switchable entity (smart plugs, but maybe also TV/media players or really anything that has an on/off state) entering a standby power draw (0.7W doesnt sound like much, but x 50 it adds up ), and a max/ON power.
If its a device that can be dimmed, like a light, power consumption can be calculated in function of brightness (standby power + max power/brightness percentage). This wouldnt be 100% accurate, eg RGB lights may consume less in color mode at full brightness than in white mode, power consumption may also not scale linearly with brightness, but hey, it would be good enough and a huge improvement.