Site Assessment, Design Package Review, and Pre-Installation Planning
This domain tests site evaluation before hardware is ordered: solar access, shading, roof condition and structure, collector orientation and tilt, and the route from collectors to storage or pool equipment.
Solar access and orientation
Use a true-south reference, not magnetic south; correct compass readings for local declination. In the northern hemisphere, a solar thermal array generally faces within 30° of true south. Year-round domestic hot water is usually mounted near latitude tilt; winter-dominant loads tilt steeper, and summer pool loads tilt flatter. Check the solar window from about 9 a.m. to 3 p.m. on December 21 and June 21, and account for future tree growth and new construction.
Roof and structure
Record roof covering, age, layers, rafter size and spacing, sheathing condition, and span. Confirm the roof can carry collector dead load plus wind and snow loads; a licensed engineer may be required. Identify penetrations, vents, chimneys, and access paths, and verify that collectors will not block attic ventilation or roof drainage.
Loads and routing
Size collector area from the daily hot-water load or pool surface area, not from available roof space alone. Map the pipe route for length, insulation, freeze protection, and drainback slope. Locate the pool pump, filter, heater, and heat-exchanger bypass.
Worked example
A roof reads 150° magnetic with 13° east declination, so true azimuth is 163°-within 30° of south. December shade at 10 a.m. covers the west third of the roof, so shift the array east and shorten the pipe run.
Traps
Using magnetic south; ignoring winter shade; assuming an old roof will last the system life; forgetting pool equipment access.