Regular plain old silicon solar cells in an aluminium frame can supply all humanity’s energy needs many times over. (The fact that wind often gets us through the night just makes renewables more reliable and therefore cheaper.) But the myth remains that we MUST have Gallium, Tellurium, Cadmium and Indium. But here is a list of the rare-earths “boosters” to solar, what their special functions are, and even in some cases some more abundant alternative materials we can use.
Gallium – replace with regular boron!
A solar cell is made of two types of semiconductors, called p-type and n-type silicon. The p-type silicon is produced by addingatoms—such as boron or gallium—that have one less electron in their outer energy level than does silicon. Because boron has one less electron than is required to form the bonds with the surrounding silicon atoms, an electron vacancy or “hole” is created.
ACS – 2014
Tellurium is just another option. If it runs out, we’ll go back to Poly-Si above.
Amongst the rarest of the stable elements on the periodic table and an important ingredient in the emerging thin-film solar panel sector, tellurium embodies what it means to be a critical metalloid – an element that possesses the properties of both a metal and non-metal…
…While the solar market continues to be dominated by traditional silicon solar panels, CdTe panels are becoming increasingly popular. This is due to these thin-film panels’ ability to absorb sunlight close to the optimal wavelength for converting to electricity, and they are relatively inexpensive to make.
Mining News North – September 2021
Cadmium telluride is a competitor to normal silicon – but is only in 5% of solar panels.
Indium not needed in normal crystalline panels but is part of the thin-film variety. They’re working on thin-film without indium. (February 2021)
The EU says even CIGS cells with indium are not a problem as they’re getting so efficient. ”The researchers said the indium content per gigawatt of modules, currently about 15 tons, can be reduced to several hundred kilograms, or even lower.” (August 2021)
Silver can be replaced by copper. Global Energy prize – September 2022.
Bezinga – May 2022.
Electronics for U – September 2022
Pv-Magazine – September 2022
Selenium is a historical footnote – discovered to be photoelectric in 1874 but abandoned by 1949. Silicon emerged as the winner.
Eclipse Now 