The HGL systems offer tremendous energy savings at a tremendous price -- so high, that I doubt you would ever recoup the cost of purchase. One indoor banana would require a $700 to $1200 (US) expenditure.
One 100W high-end system (Procyon 100) will not be sufficient for fruiting banana plants, you will need two -- each placed off-center and pointing back down towards the base of the plant. To use the 3 Watt single wavelength bulbs, you need arrays of them: for every 2 630nm bulbs you need about 4 660nm bulbs, 5 455nm bulbs, and 6 470nm bulbs. That's a total of 17 bulbs in one array, but you will need at least 2 arrays for one banana plant or equivalent vegetative growth.
Their approach to light source is based on combining 4 specific wavelengths (455nm, 470nm, 630nm, 660nm) in one system. In doing so, they minimally approximate the wavelengths most used by common ornamentals. There is nothing in the lamps to diffuse frequency, so the output is very specific and misses some desirable sub-dominant wavelengths. The transmitted wavelengths will interact with each other to produce a small amount of additional wavelengths, but these will be outside the photo-active range of plants.
I would prefer to own a bulb that utilizes frequency modulation to better approximate the greenish curve shown below. The newer florescent plant light bulbs all do this very well, and very affordably!
