DEFINITELY not for this kind of project. You want to keep the power as low as possible while maintaining a respectable MH/s. This rig I have should be able to theoretically push out 300MH/s on 250-300W. Plus, I don't have enough room to create a device of any sort capable of suppling 750W in a green way.
If it helps, I get 410MH/s on 300W (measured at AC) with a not-green CPU and a few HDDs since it's my gaming rig. If you drop to a low power CPU and minimize the HDD, I'll think 250W should be pretty doable. Personally I would had done this, might had gotten the panels cheap since the company next door sells them. Except my location doesn't give me enough direct sunlight
