Solar Stirling Engine

[ToeJam]

Hi all;
I'm doing a research project into solar stirling engines, and I'm just wondering if anyone has seen one in the wild, actually working and producing usable power?

I've seen the promo videos for the ones that were supposed to be built in California, and heard about a European competitor.
But I've never actually seen an array of them working and putting power into a grid.

Thanks in advance
Toejam

"Flux capacitor ... fluxing"