I think if you used this TEC http://www.customthermoelectric.com/...Q_spec_sht.pdf to do your 4 parallel sets of 4 TECs in Series, so 16 TEC's on a 12v PSU you could achieve some decent numbers. Aim for 20*dT, each TEC get's 3v and about 5.5amps, and uses 16.5watts and has a Qmax of about 20-22 at 20*dT, so with all 16 TECs your using about 264 watts to give you a Qmax of about 320w. So keeping it simplified like that your doing pretty well, of course a lot of other stuff will come into play, but that is a basic approximation of what can be done with lots of these lil suckers.