OK, i get it now (i think):

with the 400W TEC linked above i can keep a 395W heat source at room temperature (0dT), or i can cool a 130W source to 50C below room temp (50dT) (or anywhere in between). with 4 in series i can cool 1120W@0dT or 370@50dT ("very" ballpark - but hopefully, you get the point). is that about right? (not the actual math - but the relationships)

of course i understand that you'll never be able to run a TEC at 100% and get 0dT (room temp with a 400W source) - the CoP at 100% would probably be about .6 - so you could maybe cool a 240W heat source and keep 0dT...maybe, i don't know...