This feature has the third most votes already, so I’m quite sure devs have this on their radar but please continue to vote it up!
I was also quite “blue-eyed” on how an implementation could be done, however, it’s not that simple.
Quick check, what would the cost be for a device when (if) you produce your energy yourself (Solar panels)? How do you then calculate the cost for your light vs your boiler?
Then there’s a clear complexity brought in from the fact that many countries/regions have different pricing originating from the grid companies and it’s quite complex to bring in all this at the same time.
My personal opinion is still that an MVP would suffice as a starting point.
Pricing from template entity and consumption like the “mains” would enable budgeting “on-times” e.g. “spend $10 on heating the boiler today” no matter if I produced the energy consumed or not.
This topic was also brought up during the “What the Heck” month.
Please see the thread here where the complexity on this task is described: WTH!? - Why can't we see electricity cost for individual entities in Energy dashboard? - #19 by Boba_ferret