Firstly, you would have to be under some kind of investigation already for the cops to be able to even request your personal usage data and secondly, they surely have better things to do than prey on DIY growers with all the serious drug trafficking and money laundering going on all the time.
What a sad world this would be if your electricity supplier forwarded your info about domestic use onto the police for whatever reason. It would be even more sad if the cops harassed your ass for growing a plant or two when they know you're not a dealer.
Just imagine the blunder if the police showed up at your door based on electricity use, only to find you're growing some perfectly legal plants or your kid was playing games on his 1000Watt gaming PC setup, while your washing machine and dryer were operating for hours every day.
There are a thousand reasons for increased domestic electricity use. Until the use of electricity is limited by law, no one has the right to even check on you. You still have the right to privacy.
And if I'm wrong, then a revolution is long overdue. Otherwise, we may as well just kill ourselves.