No, power augers (even hydraulic ones) don't work well in incredibly rocky clay soil. My landlord tried to use one a couple years ago, got about a foot deep, and gave up and grabbed a shovel and digging bar.
I have the privilege of being licensed and insured for such and have a working relationship with the county fire marshall who issues the permits, so I used a rock bar to open a little hole to the right depth and then sprung the hole with a small binary explosive charge. Covered with matting hung from a borrowed tractor's bucket, so no danger of launched projectiles.
Saved a whole lot of backbreaking digging, do recommend.
In my experience, if you’re willing to sacrifice the bit, they can save time in the earth composition you mention vs manual excavation if the driver has enough power (especially if mounted to a skid steer, just drive the bit towards success depth). Thanks for the reply, always curious on improving the speed and efficiency of ground mount installs.
