In addition to asking "Do you need that much?" (which is a good question), I would also be asking if you have the time to take care of that many plants? Taking care of this many plants by yourself can be terribly hard and it will be about a full time job.
If you pay your power bill it will not be a problem. It is a common misconception that people get busted because their power bill is high, but that is not true. People get busted because of stupid things they do, like telling other people, leaving growing debris around, not dealing with odors--that kind of thing.
While I think that Sherrwood's estimate of every plant yielding 4 ozs is optimistic, a 45 plant grow is going to yield a lot (if you have the time to take care of them properly). I am in a non-MMJ state and the penalties get way worse over 25 plants so I always keep my plant count below that. That is something you should keep in mind--while you will not get busted for using a lot of power, there are a lot of things that can and will trip you up. I always know that I could be busted at any time for reasons beyond my control and therefore keep by plant count below the "mandatory jail time" count, which is 25 where I live.
So, questions to ask yourself...Do I need that much? Do I have the time to take care of this many plants as they should be cared for? Am I willing to go to prison?