We claim the ornamental design for a photovoltaic panel system, as shown and described.
FIG. 1 is a perspective view of a photovoltaic panel system showing our new design;
FIG. 2 is a front view thereof;
FIG. 3 is a rear view thereof;
FIG. 4 is a top view thereof;
FIG. 5 is a bottom view thereof;
FIG. 6 is a left side view thereof;
FIG. 7 is a right side view thereof;
FIG. 8 is a perspective view thereof, shown in environmental use;
FIG. 9 is an expanded view of the respective region marked in FIG. 1;
FIG. 10 is an expanded view of the respective region marked in FIG. 1; and,
FIG. 11 is an expanded view of the respective region marked in FIG. 1.
The dash-dot-dash broken lines immediately adjacent to the shaded area define the bounds of the claim design and form no part thereof. The remainder of the broken lines are provided for environmental purposes only and form no part of the claimed design.