Residential its harder but an industrial/commercial property could possibly have multiple power inlines, a diesel generator for emergency power, and perhaps solar panels on the roof and batteries. It may have agreement to use power within specific ranges during the day for different prices and supply power back to a power company or neighbouring businesses.

Under those conditions it's always possible to divert power to 'adjust' the perceived power usage.

My point was that block chain doesn't validate anything - a private key will prove that the data (good or bad) is from the specific user, block chain won't validate that its good.