The ornamental design for a solar panelassembly, as shown and described.
FIG. 1 is a front top left perspective view of a solar panel assembly showing our new design;
FIG. 2 is a front top right perspective view thereof;
FIG. 3 is a front elevation view thereof;
FIG. 4 is a back elevation view thereof;
FIG. 5 is a right side elevation view thereof, the left side view being symmetric thereto;
FIG. 6 is a top view thereof; and,
FIG. 7 is a bottom view thereof.
The diagonal shade lines illustrate transparent elements covering components of the solar panel assembly, where the internal components are not transparent.