You could use a FishNeedIt 2 bulb T5HO light, which would give you around 40 micromols of PAR, with the light sitting on top of the tank. Or, you could use a Catalina Aquarium one bulb T5HO light suspended about 10-12 inches above the top of the tank, to get about the same amount of light. Or you could use 3 Home Depot worklights, with the aluminum dome reflectors about 10 inches in diameter, with 14-15 watt CFL bulbs, with the reflectors sitting on top of the tank, for about the same amount of light. Or, you could hang those HD worklights about 2 inches above the top of the tank, with 23-25 watt bulbs, for about the same light.
So, you can see that the bulb wattage isn't what counts, but what specific lights you use, and how high they are above the substrate. About 40 micromols of PAR is probably enough light to grow HC (dwarf baby tears), but you need good CO2 to do that, even with more light.