[Qwertious]

Solar thermal requires lots of pipes that you pump molten salt and/or steam through, it's far more expensive than PV. The efficiency doesn't matter as much as the cost, unless you're limited by land to build grid PV on.

There are no moving parts in PV or these bricks, which means they'll have near-zero maintenance costs.

Also I'm pretty sure solar thermal can't heat steel - it relies on steel pipes throughout the entire system.