Here's interesting situation ... Solar photovoltaics rely on the element indium, which has a supply constraint. Can we sustainably grow the production of solar panels to satisfy demand, given this constraint? ...
... "For high-power solar cells the issue boils down to a single element used in their manufacture: indium. While PV cells are manufactured a little like any other semiconductor device on a silicon frame, the power efficiency of silicon-only cells is pretty limited. " ...
Via Fast Company:
Renewable Energy Solar