Solar Road Stud - Road Safety Equipment Supplier - RoadSky. Solar road stud is used on Highways, at parking lots, also used on curves on roads. Material:Cast Aluminum, Plastic, Glass. Solar Panel Voltage:2V/100-200mAH, 3.5V/78-120mAH and etc. Solar Panel Material:Monocrystalline silicon or polycrystalline silicon.