In 1949 a solar furnace for melting steel was built in France.
We should add...this French furnace in 1949...handled 50kW of power. It was a state-funded university project. You would have thought that he’d have won the Nobel Prize for stuff like this....but apparently didn’t get much publicity out of the episode. There’s also some suggestion that he really stepped on various toes of the French and European science community by building this and proving several industrial uses. Even the Wiki guys barely give him eight lines of text. He was probably sixty years ahead of his time.