Solar alarm light

1. 1The ornamental design for a solar alarm light, as shown and described.

FIG. 1 is a perspective view of a solar alarm light showing my new design.
FIG. 2 is a front view thereof.
FIG. 3 is a rear view thereof.
FIG. 4 is a left side view thereof.
FIG. 5 is a right side view thereof.
FIG. 6 is a top view thereof.
FIG. 7 is a bottom view thereof; and,
FIG. 8 is a rear, right, bottom perspective view thereof.
The broken lines in the drawings depict portions of the solar alarm light that form no part of the claimed design.