Thanks for the suggestions - shop does have 4 good quality windows on the
long south wall, a couple on the east and none on the north or west. Has a
dark roof too. As time and budget allow, I'll consider adding solar thermal
collectors, but for now I've pretty much spent what I can....
....The house is a passive solar design, with r50 roof, r38 SIP first floor,
and r28 ICF basement. Overhangs and shade roof designed to shade windows in
summer, south half of house has a stepped down sub-floor to accomodate
1-7/8" of gycrete with tile over it for the main floor thermal mass, and the
walk-out basement has good underslab insulation. All energy star appliances
and every light and lamp is either CFL or T5. Energy star 5+ / HERS score
of 50! Electrical was setup to easily accept PV when it drops in price, and
next spring we plan to add solar thermal for dhw if budget allows.