Why Sustainable Power is Unsustainable

The solar cell trend is to capture multiple frequencies of radiation - the area under the curves, not just a single frequency.
As efficiencies increase, the solar cells will be recycled. However, the market begins with those early adopters in corporations and homes to create a large stable market to provide the benefits of mass manufacturing and multiple competitors to drive the price down.
As the market goes mainstream, then the early adopters will adopt when it makes economic sense and recycle their solar cells. In the recycle process, the precious metals will be recycled, and new processes inserted.
Environmental activists have to figure out the economics and actually promote mining of minerals to build a sustainable solar cell market. The demand may make it too expensive, and then a crash will make it desireable to buy, but not to mine or manufacture, or even recycle.
And if you like solar cells, you may want to look at wind generators. After all, they respond 24 x 7 to wind and not just the sunrise to sunset curve. Sustainability there is in the new technology of switched electric generators which will convert wind of all velocities. Engineering goal is 200 mph, about that of a small airplane.
Finally, the environment cry for recycle and renewables has given way to sustainable. Insulation is the ultimate sustainable technology.Moving all people-occupied building structures to a higher level would go a long way to reducing the demand for energy allowing the dynamic power, light and heat energy technologies a chance to get more efficient and economic.
David