Grow lights?

I'm building a 15x15(ish) greenhouse for the winter, going to make some hydroponics towers inside. what grow lights should I get? I'm growing lettuce, some basil/dill/other herbs, and maybe some other leafy greens. no fruit. I've read that leafy greens like 30 watts/sq ft, how would that work for a hydroponics tower? also, I'm off grid with nothing but solar and propane. In the Pacific Northwest. Thanks!