I worked with Arno about a decade ago and he was still sharp as a tack.
Since the pressure varies depending on solar flux and how much was in the tank we couldn't use a turbine (the shape of the turbine is tuned to a constant flow) so instead used multi-stage steam engines (the first new steam engine designed probably in 75 years. These were ordinary container-sized pressure vessels and the steam engines were built into a container too. Easy to repair; you could make your own parts, and last forever.
Cheap PV and batteries killed it.
Arno was full of good advice.
Positive Q sign = lying in bed unconscious with tongue drooping down one corner of mouth; means either dead or will be soon.
Source: Retired neurosurgical anesthesiologist (38 years in practice)
My proof: https://scholar.google.com/citations?user=5DdrMc8AAAAJ&hl=en
In general land is less expensive than the cost of trackers or concentrators (capital cost incl installation, plus op ex of maintenance & power) so you deal with your cosine loss by just installing more panels.
https://www.greentechmedia.com/articles/read/terrajoule-unst...
The advantage of the mechanical system is that it would last indefinitely and could be repaired on site. People in India could make most of the spare parts themselves and do the maintenance themselves.
But the advantages of the semiconductor + battery systems were: 1 - no moving parts and 2 - massive economies of scale due to mass factory production of highly uniform parts that could be used in lots of applications. Makes sense that it won -- our approach was superior only in certain applications.