Can a section 8 renter pay more for a power bill than actual rent?

Yes. However, if you see that this is the case with you, you should write to the Housing Authority and let them know that despite your best efforts to conserve electricity (and/or other utility) your bill is excessive (perhaps you're using medical appliances?) They should increase your utility allowance accordingly (they'll ask you for your electric and other bills of the last 12 months, then average them out, then that will become your utility allowance, which then will be deducted from your total tenant payment (TTP). If your power bills exceed your TTP, you may end up paying no rent, and maybe get a check for utility bill assistance.