Okay, so according to google, a 46 bowfront is 36x15x20
If you look here:
AI Sol - Performance
There is a par chart for a 36x36 area at a 24 inch depth. With some creative rock work, you could probably make one unit work - but you would have some lower light in the corners of the tank assuming you mounted the module in the middle.
I need to play around with mine a little bit, but I appear to get pretty good coverage on the 180 with the three units. There is a lot more shimmer than what I had with my MH fixture, and there are some shadows created by the rock (more so than with the MH). I think this is due to the optics on the LED's versus the reflector on the MH
Since your tank is only 20 inches deep, the other thing you could do is look at replacing the 40 degree optics in the center pucks to 70 degree optics that are in the corner pucks. This would give you less depth penetration, but more spread. From the par charts that I've seen, you'd probably be okay
The other person you may want to bounce this off of is Parachute, I beleive he had the first gen unit, and has upgraded to the new Sol Blue