[pfdietz]

That's just in the lab. If you buy PV modules right now the cells will not be doped with rare earth elements. And almost everything demonstrated in the lab doesn't progress beyond there (which is fine; that's how technology R&D works.)

I think the closest one could come to making the "REE in solar" claim make sense would be decoloring agents for the glass. Cerium could be used for this, but I think manganese is cheaper.

[tullianus]

Cerium is common in solar coverglass used in space, but I'm not sure I've heard of it being used for terrestrial applications.