The ornamental design for an solar panelassembly, as shown and described.
FIG. 1 is a front top right perspective view of a solar panel assembly showing my new design;
FIG. 2 is a back top left 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 right side sectioned view thereof;
FIG. 7 is a top view thereof; and,
FIG. 8 is a bottom view thereof.
The broken lines shown illustrate the portions of the solar panel assembly that form no part of the claimed design. The diagonal broken lines illustrate transparent elements covering components of the solar panel assembly, where the internal components are not transparent.