The ornamental design for a panelfan, as shown and described.
FIG. 1 is a perspective view of the panel fan;
FIG. 2 is a rear plan view of the panel fan of FIG. 1;
FIG. 3 is a bottom plan view of the panel fan of FIG. 1;
FIG. 4 is a front plan view of the panel fan of FIG. 1;
FIG. 5 is a right plan view of the panel fan of FIG. 1;
FIG. 6 is a left plan view of the panel fan of FIG. 1; and,
FIG. 7 is a top plan view of the panel fan of FIG. 1.
The broken line showing of portions of a fan is included for the purpose of illustrating environmental structure and forms no part of the claimed design.