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Install the array mounting and panels

Mount the panels at the design tilt and azimuth, firmly enough to survive local wind and snow, with airflow behind them and access for cleaning.

How

Use racking rated for your wind and snow loads and follow the maker's fixing and spacing instructions.
Set tilt and azimuth from step power-4 and power-5. In snowy areas, steeper tilts help snow slide off: in NREL modelling, snow shedding speeds up with tilt, and systems tilted at latitude lost less to snow than 20 degree systems across most of the contiguous US.
Leave an air gap behind panels: hot panels lose output (about 0.47% per °C for standard modules in the PVWatts model).
Use stainless or compatible fixings to avoid corrosion, especially near the coast. On coastal sites choose panels tested to IEC 61701 (salt mist corrosion), and near barns, manure stores or poultry houses consider panels tested to IEC 62716 (ammonia corrosion); ask the maker for the certificate.
Cover panels or work at night while connecting strings, since panels are live in daylight.
Route and support cables away from sharp edges and sunlight damage, using UV rated cable and conduit.

Safety: Use fall protection on roofs. Treat every panel cable as live.