Overall 300 watts of cfl is probably enough, but the problem with cfl is penetration of the light. If you dont get those lights right up to the leaves then they wont get enough light. Discharge lamps like hps and mh dont have that problem so much. It would be better to get 8 40watt cfls and arrange them right up to the leaves and flowers, otherwise your yield will be really small. Thats the only way to do cfl grow, and that is why you see some peoples pics of cfl grows with all these lights hanging all over the place, to get them as close as possible. Good luck!