First Solar Snaps Up Silicon Valley Solar Startup

Here's an interesting development for all you solar tech wonks: Industry giant first Solar announced Tuesday that it's acquiring the little-known startup TetraSun so that it can, in the words of ReWire's pal Ucilia Wang over at GigaOm, "add expertise around silicon solar cell manufacturing to its technology portfolio."

Seems straightforward enough, until you remember that First Solar now relies on a completely different photovoltaic technology, and that this acquisition represents a potential major technological shift for the company.

 
The Tempe, Arizona-based First Solar, which is the U.S.'s largest photovoltaic panel manufacturer, has built its business by fabricating huge numbers of thin-film solar panels using a cadmium telluride semiconductor, which until recently was more economically produced than old=school silicon crystal semiconductor-based solar cells.

Though First Solar has been willing to examine other technologies, and even went so far as to dip its tow into copper-indium-gallium-selenium (CIGS) semiconductor research until budget constraints killed that program last year, the whole of the company's growth has been due to cadmium telluride PV panels.

That reliance is a double-edged sword. Using cadmium telluride as your semiconductor of choice allows you to make relatively inexpensive solar cells that are thought to be capable of efficiencies approaching 20 percent, at least in laboratory conditions. But real world conditions aren't the same as those in the lab, and First Solar has had at least one batch of panels turn out to be disappointingly less productive than they'd hoped, necessitating embarrassing announcements in the trade press.

And as cadmium is a toxic heavy metal, First Solar's deploying thousands of panels that contain cadmium telluride has raised environmental toxicity concerns among people who live near the company's utility-scale PV installations. Whether or not those concerns are warranted, the use of cadmium telluride as a semiconductor definitely raises the stakes when the panels reach the ends of their useful lives, requiring recycling as a potentially hazardous material.

In any event, plummeting prices for silicon crystal PV cells have undercut cadmium telluride's economic advantage over silicon. It isn't surprising that First Solar is showing interest in exploring ways to break into that older technology in economically efficient ways. According to Wang, First Solar hopes that acquiring TetraSun might help the solar behemoth build silicon cells with a 21 percent efficiency, which is several percentage points more than commercially available silicon-based PV cells now reach. A few percentage points doesn't sound like much, but boosting output to 21 percent efficiency could mean that a roof now capable of holding 1,000 watts' worth of solar panels could hold 1,300 watts in the same space. Which means more green power with a smaller footprint.