Project Site Assessment
What the exam tests
Site assessment tests your ability to judge solar access, shading, roof/site conditions, electrical service capacity, and customer load. The goal is a design that fits the real site, not just a nameplate array.
Core rules
- Solar window: evaluate 9 a.m.–3 p.m. solar time; use a sun-path tool and true south, not magnetic south.
- Shading: identify near and far shading, including trees, chimneys, and future growth. One shaded module can limit a string; bypass diodes reduce but do not eliminate loss.
- Roof condition: inspect covering, age, decking, framing, and attic; measure usable area after fire setbacks and access paths.
- Structural: verify rafter size, span, spacing, and snow load; a site assessment is not a structural engineering letter.
- Electrical: record service voltage, main breaker, busbar rating, panel spaces, meter location, and utility transformer; check interconnection limits early.
- Load: review 12 months of bills and major loads; distinguish energy offset from demand reduction.
- Ground mount: check soils, frost depth, floodplain, setbacks, and trench routes.
Worked example
A roof measures 20 ft × 12 ft. After 2 ft fire setbacks and access, usable area is 16 ft × 10 ft = 160 ft². A 400 W module is about 17.6 ft², so 9 modules fit: 3.6 kW STC. With 4.5 peak sun hours and a 0.80 derate, daily energy ≈ 3.6 × 4.5 × 0.80 = 13.0 kWh/day. If the customer uses 30 kWh/day, PV offsets about 43%, not the whole load.
Traps
Using compass south; ignoring afternoon shade; counting every square foot as usable; skipping busbar and main-breaker checks; assuming bill kWh equals array size; treating a site visit as a structural stamp.