oops. I meant about 150W of LED (for that size screen)
But you don't really want to greatly oversize the screen, that can cause the growth to try to spread out too much. Just size it according to how much you feed: 12 sq in for each cube of food per day, or for single sided, double that. Then once you figure up that size based on what you actually feed, don't go more than 2x that size.
So if you feed 4 cubes/day, that's 4 x 24 = 96 sq in, 2x that is about 200 sq in.
Now for lighting, for single sided, you want to shoot for the higher end light level once the screen is established, lower to start.
For LED, I recommend one 660nm Deep Red LED every 4-8 sq in. For so 100 sq in single sided, that's about 12 to start, 24 once the screen is going strong.