The solar panels present a large flat surface (sail) to the wind, and can upset the whole apple
cart (so to speak.) If you normally have wind, then you should tie the unit(s) down with small cables or ropes to two or three ground anchors. Anchors can be stakes, bolts in concrete, or even heavy objects that can't blow away.
Grover--- Resident prognosticater. If you need specifics, contact me at email@example.com.