BigV makes a point, even tho on a cloudy day, UV rays still pass thru clouds. Indoors you are simulating the sun, the way i figure it, a light schedule like you are talking about would throw the plants off considerably (imagine if all of a sudden the sun switched to an 8-4 schedule) not to mention you are going to need to change your light schedule when you start flowering, so what may save you 5 bucks now, is gonna be completely different in a month or 2. Im just offering my 2 cents here, but if I were you, i would find an electrician (preferably an experienced friend) to wire your HPS to a 240V source, and run your lights during the day to avoid any detection. My 400w hps jacked my bill up a grand total of 15 bucks (altho my room is big enough to not require an exhaust fan i cant imagine that would add much more). So even if you triple that number for the 1000w, 45 dollars isnt bad, try going thru ur house and changing out all of your bulbs to CFLs, and practice good energy saving techniques (turning the fridge down, microwave less often if you have a gas oven, dont heat or cool rooms you dont need to) If all else fails you can ask your electric company to put you on a fixed plan where they average your last 3 months usage and create a fixed rate from that. I dont think your idea is retarded, i just dont think something mother nature designed to grow off of her light schedule is going to prosper having shorter "days"