First Solar was trying to compete with high-efficiency silicon when it acquired early-stage startup TetraSun in April 2013 in the cadmium-telluride (CdTe) vendor's first foray intosolarsilicon.

It was a hedge against its own CdTe material.

Well, according to the company, “With the success of our CdTe roadmap reflected in our record 22.1 percent cell efficiency, along with the proven higher energy yield and superior performance inherent in our thin-film technology, that hedge is no longer needed.”    

And so ends First Solar's $100 million high-efficiency silicon solar experiment -- a rare instance of the company not meeting its execution promises. At one point First Solar made the aspirational claim of being set to commence "commercial-scale manufacturing of the new technology in the second half of 2014."

First Solar is "reallocating production capacity at its Kulim, Malaysia facility to support a new assembly line dedicated to the company’s recently announced Series 5 thin-film photovoltaic module offering," and will cease production of its crystalline silicon solar panel product currently being built there. 

The hopes for the TetraSun technology included module efficiencies over 21 percent using 156 mm n-type wafers with no light-induced degradation and no potential-induced degradation.

At the time of the acquisition, GTM Research's Shyam Mehta said, "The use of copper metallization really does give TetraSun a shot at being a truly low-cost, high-efficiency technology concept." However, he cautioned, "There are multiple barriers associated with copper as a metallization solution, and thus far, little progress has been made at the commercial level."

TetraSun was a 14-employee startup with $12 million from investors and little more than a pilot cell manufacturing plant when acquired by First Solar.

Now, First Solar suggests that it can match the efficiencies of average c-Si modules and believes it can hit ~19.5 percent module efficiency with CdTe in 2017. The firm also sees credible long-term paths to 23-percent-efficient and 25-percent-efficient CdTe cells.

Raffi Garabedian, First Solar's CTO, has noted, "We've improved the efficiency and energy density of our mass-produced commercial PV modules at a rate at least three times faster than our multi-crystalline Si competitors. We fully expect to further separate ourselves from the pack in coming years."

First Solar's lead CdTe manufacturing lines were producing PV modules with a 16.4 percent conversion efficiency in Q4 2015.