High electricity usage is very difficult to conceal. Many people attempting to hide activities with high electric draw (e.g., clandestine indoor marijuana growing) have been caught this way.
The growers that got caught were stealing electricity, or not paying for it. The growers that pay for electricity, and pay the power company, the power company usually doesn't mind them since they are paying.
The big grower that was caught before, was not paying for electricity and the power company decided to investigate why there was a large consumption in a certain area and why they were not getting paid. So ... they caught the grow operation.