The ornamental design for a solarstreetlamp, as shown and described.
FIG. 1 is a first perspective view of a solar street lamp showing my new design;
FIG. 2 is a second perspective view thereof;
FIG. 3 is a front elevational view thereof;
FIG. 4 is a rear elevational view thereof;
FIG. 5 is a left side view thereof;
FIG. 6 is a right side view thereof;
FIG. 7 is a top plan view thereof; and,
FIG. 8 is a bottom plan view thereof.
The broken lines in the drawings illustrate portions of the solar street lamp which form no part of the claimed design. The diagonal lines in the drawings indicate transparency.