- An orientation within 30° of due-south is best. Within 60° of S, with a low-slope angle, is OK but energy production can be affected by up to 10%.
- Collector (roof) slope angle of 15° (3:12) to 35° (8:12) is best.
- Sun for at least 6 hours/day spring through fall. Winter shade will not affect annual energy production much
- Open area clear of shading from trees, buildings, etc.
- Roof should be in good condition – at least 10 years life remaining