i believe tha average cost is 9cents...but that doesnt really matter per se, b/c electric companys charge by ur peak not ur total...so i u average bout $40 a month, and jus one time for like 30 min or something u hit a big spike, which put it at like we'll say $60, u will b charged $60 even tho it was jus for that brief moment, even if turn ur power off for the rest of the time....so try to run the lights when nothin else is runnin, and u shouldnt have to much of a big jump in ur electity cost...