What if the information is kept strictly in the system and encrypted so that no one can access it except the system. Then the system generates the proper aggregate reports. This would protect individuals rights to privacy while allowing a mindless system access to the sensitive information and manage the grid properly. Surely aggregate information is all the power company people would need to operate a smart grid. (Both aggregate across a household over a period and aggregate of all customers in real time)
Now of course there could be questions about back doors, hackers, etc but at least no one would be able to legally use the information against you in court or to obtain a search warrant (I am assuming that would be part of the 'deal').
Maybe I am missing something huge, so please let me know if I am, but this sort of solution seems like a reasonable way to get both of best worlds.