Solar PV Installation and Mounting
Domain 4 tests hands-on execution: how arrays are attached, flashed, bonded, torqued, and protected on roofs, ground mounts, and other structures.
Roof attachment and weatherproofing
- Locate rafters with a stud finder and confirm by pilot hole; lag screws need the manufacturer's minimum embedment (commonly 2.5–3 in) into structural members.
- Every penetration needs flashing integrated with the roofing - a flashed standoff or pitch pad plus roofing-compatible sealant. Sealant alone is not flashing.
- Keep modules 3–6 in above the roof for airflow and cell cooling, following the rack manufacturer's standoff height.
Mechanical rules
- Mid-clamps go between modules and end-clamps at array edges; they are not interchangeable.
- Torque to the rack manufacturer's specification with a calibrated wrench. Over-torque crushes frames and voids warranties.
- Bonding: rail splices, module frames, and rack parts need listed bonding hardware or a continuous equipment grounding conductor sized per 250.122.
- Conduit: support within 3 ft of boxes and every 10 ft; add expansion fittings on long runs and at roof transitions; use UV-rated, wet-location raceway outdoors.
Worked example
For a 6:12 roof pitch, rise ÷ run = 6 ÷ 12 = 0.5, so the roof angle is tan⁻¹(0.5) = 26.6°. Instead of eyeballing the tilt legs, set them from the rack manufacturer's table for 26.6°; rails then run parallel to the roof plane and clamps land inside the marked clamp zones on the module frame.
Traps
- Torquing by feel rather than a calibrated specification.
- Swapping mid-clamps and end-clamps.
- Skipping bonding jumpers across rail splices.
- Standing or kneeling on module glass; carry modules vertically by the frame.