Storenergy.rs

900c
https://storenergy.rs/ and storenergy.rs patent This design has the lowest wind loading. Ceramic balls at the focal point are circulated in a loop with an auger screw mechanism heating the balls upto 900c. The balls are deposited into long steel tubes, generating super heated steam. Efficiency is much higher than molten salts(500c).

https://areosenergie.com/ae/eng/ same type of fresnel tech as storenergy with the most efficient way to store energy, which is the biggest issue with solar and molten salts.

jlanka
https://www.youtube.com/watch?v=qj7m-sZRiaA stores hot air in fire bricks instead of salt.

links
Solar structures