Yes some brands are intended for solid rock conditions. This type here is more like a giant roto-hammer and Tapcon screw. They have units like this scattered around the country. The job above was at a friends place above Utica, NY. I think he paid $125.00 per installed post. Compared to digging, pouring concrete with an anchor bracket, etc. it was very price competitive. The screws turned it into a one day installation for the rack system. Most of the larger solar installers have access to these machines, call or google around. One installation in Germany along the autobahn they hung one of these small mini excavator rigs, with a cable, from a larger cat above the hillside. The were able to mount a large PV array on a steep, rock cliff along the highway.