Yes, I have used RETScreen and understand a solar wall can be modeled within
it. In fact, Conserval has already done this for us. In considering
SolarWallR, all the air handlers have been sized down and when I enter in
the system inputs for capacity there isn't enough juice so I have to
incorporate solar air heating into this model. Either that or autosize
everything to get 300 and subtract the retscreen model as an ECM.

So create a plenum for each air handler and then make all the plenum walls
Trombe-wall and just fiddle with it until it works, maybe. I can spend a
minute on it and try. Either way its modeling reality, right? There should
be a lot more discussion on this. Someone must have submitted an energy
model with solar air heating to USGBC using equest.

Kevin