Financial Analysts Do Not Seem To Understand That The Demand For Silicon And Tellurium By The Solar Power Industry Has Not Been Reconciled With The Reality Of The Available Supply Of Either Element

Implications: Silicon is one of the most common chemical elements in the earth's crust; it is also exteremely accessible, since the vast majority of the beach sands on this planet are fairly pure silicon dioxide which have been produced by eons of weathering of silicate rocks and quartz. Tellurium on the other hand, although relatively abundant, in the earth's crust is only accessible to us as a minor constituent of most copper (sulfide) ores, or as a minor constutent of some other less common metal ores such as some of those of silver, gold, palladium, and tungsten, for example. The ultra purification of silicon to the purity required for the manufacture of silicon solar cells is very expensive, but it is today commonly undertaken to produce the silicon used in manufacturing the bases for integrated circuits.     Tellurium on the other hand is only produced as a byproduct of copper refining and then only 1 oz of tellurium is produced for each 500 pounds of copper.        

Analysis: The conversion of sunlight to electricity by certain materials has been known since World War II research and development produced ultra pure materials such as silicon and germanium, which were developed to eliminate the need for some mechanical switches and vacuum tubes in radar, so that it could be miniaturized and made more rugged for carrying by aircraft and warships in combat conditions.

As purification techniques developed originally for silicon and germanium were expanded, so that many other elements could be ultrapurified, research scientists began studying the electronic properties of materials made by starting with ultrapure elements and carefully adding impurities to them at known levels. The transistor was born this way in 1947.

After 50 years of research into maximizing the efficiency of the conversion of sunlight into electricity there have been developed materials, such as metallic tellurides and methods of creating large surfaces (films) of such materials on conductive surfaces and techniques of wiring them together which have resulted in demonstrations of (solar) conversion efficiencies of more than 20%.

The original 'silicon' solar cells have now been engineered in forms ranging from single crystal to amorphous (non crystalline) and even polysilicon (multicrystalline) films which have conversion efficiencies of more than 12%.

It would seem then, if the materials are available, and if they are inexpensive that the science and engineering of solar cells have reached  practical levels.

The problem is that solar cell generation of electricity is not considered competitively economical at the best conversion efficiencies attainable with silicon based cells.

This is unfortunate, if true, because there simply isn't enough tellurium produced annually- the total is around 100 tons per year- to enable the production of enough telluride type solar cells to produce any but a tiny fraction of the electric power used in the US, much less the world. 

There is no possibility whatsoever of tellurium production being ramped up to even double what is available today, because that would entail doubling the global production of copper, and, simultaneously, stopping the further expansion of cheaper copper purification by solvent extraction leaching (SXL) in place of todays' power intensive electrolytic  refining.  SXL reduces the production of tellurium byproduct from copper refining, and so tellurium production has probably peaked.

If electricity production gets expensive enough to where 12% conversion efficiency of silicon type solar cells is economical then solar conversion will become a general source of electric power production, because factories to produce polysilicon and then ultrapurify it can easily be built if the demand is there!

If in the mean time the political objections to the generation of electricity by nuclear reactor based generators are overcome then uranium and/or thorium which are much more common than tellurium and more accessible will end the need to develop solar cells except for remote areas or space craft.

The supply of raw materials for the highest efficiency solar cells now known does not exist, and as soon as financial institutions realize this, the solar cell mania will fade to black.