Spot on. I made a whole bunch of Solar Concentrator models and did a number of calculations on them. The work was probably flawed for very precise budgeting but order of magnitude should have been correct and even then it would not work, not even close.

The best I found was a moveable array of mirrors and stationary collectors but this too is fragile and a maintenance headache. Leaks of working fluid and mechanical problems would ruin the economics even if you could get the basics to work out in your favor.