HJT solar modules are accelerating, as they are highly efficient, and easier to manufacture. But HJT could also be a kingmaker for Indium metal, which is used in transparent and conductive thin films (ITO). Our forecasts see primary Indium use rising 4x by 2050. Indium is 100x rarer than Rare Earth metals. It could be a bottleneck. This 16-page note expores the costs and benefits of using ITO in HJTs, and who benefits as solar cells evolve?