[pfdietz]

CIGS has close to zero market share. CdTe is around 5%, last I checked.

The vast majority of PV sold is crystalline silicon. The only toxic element used there is lead in backing sheets, but even that is being phased out (in part for environmental reasons, and in part because higher efficiency versions of Si cells can't tolerate the heating needed to bond to the lead; in any case there is nothing essential about the lead.) The only rare element used is silver for front contacts, but that could be replaced by copper with the use of a very thin layer of nickel or molybdenum to prevent reaction of the copper with the silicon.

The environmental impact from PV is largely from the mundane components, like steel, aluminum, and glass. PV to power the world would use these materials in small quantities compared to that used for global industrial society as a whole (global annual production of steel is 2 billion tonnes, for example). If that society deals with the impact of its overall non-energy activities, it could deal with the impact of building and maintaining a PV energy source to power it.