Thanks for your reply, Lauren.
I am in E TN. The windows in question are 3' x 5' - two in the LR, one in the BR. They will be shaded by a "hedgerow" of fast growing locust trees, about 15' away, already 15' tall, plus a large shade tree that already blocks the early morning sun. the BR is 180 sf with 8' ceilings, the LR is 200 sf with high ceiling that opens to a 100 sf kitchen.
It will be suitable for the solar storage scheme that you promote because of the "mezzanie" area over the kitchen and bath. If I sell it to someone who is interested in solar aspects I will send them your way for consultation.
I have sized the front porch so it can be used for solar collection with the addition of sliding doors. But it is a "spec house" so too soon to say if the buyer will want one.
I'm not wanting to buy specialty windows. Right now the choices are low-e coating or no coating (if allowable), essentially the same price. They are argon filled.