Outdoor Solar Lights

Although they haven’t been stolen YET, I expect my solar power lights to get stolen sooner or later. I was wondering if you know a good way to prevent them from getting stolen (other than moving them somewhere else or not putting them out at all)?. Oh, and i would not like to make a cement foundation for them or buy different ones -lol. Any help will be greatly appreciated

oh, and please make the answers reasonable, don’t be crazy.

Drill a hole through the base of each one, just below ground level, and string a plastic-jacketed steel cable through them all; then bury the cable in a shallow trench between the lights.