I bought a stand of DecorNova solar-powered lights (https://smile.amazon.com/gp/product/B01LVYSINI/) to hang on my deck. The kit came with a stake, but I didn't have anything to stake it into.

This piece is designed for standard size outdoor deck screws. There is a weird feature to give it more stability in the hot sun if you print it in something like PLA- screw a deck screw up through the bottom before mounting it.