Years ago I read paper describing a project to develop a process for electrowinning iron and sulfuric acid from sulfide ores. It was sort of economic in Norway because of cheap electricity an because iron sulfide was a waste product. It's not economic because of the cost of electricity. But if solar starts regularly producing $0.0 MWhr electricity it probably would be economic to run intermittently.

Found Source:

http://www.ulcos.org/en/docs/Ref03%20-%20Electrowinning%20-%...

tl;dr: If solar creates periodic conditions where the marginal cost of electricity drops to zero that opens up market opportunities that didn't exist before.