If you got a knock-n-talk for power consumption, someone gave your billing data to the cops. There's privacy laws that cover your power utility and any other companies you deal with. If your pwr co gave the information to the cops without a warrant, you should have done them for violations of privacy. It'd certainly have been worth a few g's plus your costs.
You're quite right- a warrant on power use alone would never happen, and in the same vein, any police contact on bases that wouldn't attract a warrant is inappropriate. You do have the right to be unmolested by police unless they have probable cause to believe you are suspected of a crime. A high power bill AIN'T 'probable cause' because the kWh figures alone do not specifically identify what the power was used for.
Now, a high power bill AND someone getting busted walking out of your house with a bag of buds- and they MAY have probable cause, but the 'evidence of drug activity' will have to come first so the cops can subpoena the pwr co for your power use history, unless of course they have trawled your rubbish or paper recycling and you were silly enough not to shred your bill- or someone near and dear to you leaked it to them.