Solar panels are prepared for installation on an array frame by initially tipping packages of palletized, bundled, vertically-oriented panels in a preparation area to form a vertical stack of horizontally oriented panel separated from the pallet and packaging material for placement on the upper supporting surface of the transport deck. The transport deck is displaced longitudinally alongside a rack of the array frame, together with a lifting machine having a lifting head on a lifting arm for transferring solar panels from a longitudinal row of stacked solar panels on the transport deck to the array frame. The lifting head may be adapted to support one panel from each of the stacks on the transport deck for simultaneous transfer from the transport deck to the array frame.