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Emerging from stealth, Part I: Solyndra rolls out solar PV cylinders to blanket commercial rooftops
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Solyndra has been one of the stealthiest new PV operators, its glistening, prominently logoed headquarters building blatantly reminding tech-savvy commuters plowing up and down the I-880 corridor near Fremont of how little they knew about the company. The shiny edifice might make some Silicon Valley veterans wax nostalgic, as the site once housed a succession of hard-disk drive manufacturing plants, starting with HMT.
But Solyndra has finally let the sunshine in, decloaked, come out of the closet, opened up its kimono--even if it hasn't quite changed some of its stealthy ways. In a well-planned media and analyst rollout, the public now knows that for this copper-indium-gallium-(di)selenide (CIGS) thin-film PV manufacturer, the world--or at least its solar-module form factor--is not flat.
While Solyndra, like many TFPV purveyors, still loves glass as a substrate, the company's meter-long CIGS-coated cylindrical modules look like a fluorescent light-bulb tube, not just another rectangular slab of the smooth stuff. OMG, Solyndra's cells are indeed tubular!
The company invited me to come by last week and see what all the fuss was about, as long as I honored the press embargo. No problem, though I did push for a facility tour as well as a sitdown with Solyndra muckedy-mucks. When I arrived, signing in and getting a visitor's badge for this secretive company involved touch-screening one of those standard Sili Valley NDAs and then standing still for a photo. First time I'd had a visitor's badge (OK, sticker) with my own mug insta-printed on it.
Chris Gronet and Kelly Truman, the company's CEO and VP of marketing/sales/business development (and both former Applied Materials men), told me how Solyndra is targeting the commercial rooftop sector. Gronet says the market potential adds up to 30 billion square feet in the U.S. alone, translating into potential electricity capacity of 150 GW and a PV market of around $650 billion.
With more than a billion square feet of CoolRoof and other reflective roofing material already being put down every year in the U.S., the opportunity to turn rooftop space into revenue-generating PV exists today. You'll get no argument from this reporter on whether there's ample space for putting PV on thousands and thousands of warehouse, retail, and manufacturing rooftops in the U.S. and elsewhere.
But Solyndra thinks its technology and installation advantages make it very competitive in what could be a most lucrative market opportunity.
Gronet pulled one of the tubular modules out of a metal carrier box, something looking similar to what might hold a pool cue or hunting rifle, to show me the critical element that has captured the attention of those venture capitalists and private equity investors who've sunk about $600 million so far into Solyndra.
The glass cylinder is black and about an inch or so in circumference, and is actually a tube within a tube. One can see that the inner CIGS portion of the monolithically integrated device has a series of swirling helical scribe lines, differentiating the 150 cells within. Between the inner and outer glass cylinders, a common industrial liquid described by the exec as an "optical coupling agent" fills the cavity and actually creates a modest concentrator effect--about 1.5x--when struck by sunlight.
There are no moving parts, as the sunlight automatically refracts through the outer tube to the inner substrate where the absorber layers do their thing. The endcaps are the only mechanical part, which are hermetically sealed using a proprietary glass-to-metal process (with no elastomers involved) that is moisture sealed and even helium-leak-tested, according to the chief exec.
Being tubular has its advantages when it comes to PV, says Gronet. Photons are not only collected directly from all angles, a kind of "self-tracking" mechanism, but diffused light is also harvested from almost every direction, and the sun's rays that don't get absorbed by the PV cylinder at first are captured when they reflect off the white membrane underneath. The circular design also provides convective cooling advantages, and the tubes don't get as dirty on the roof as conventional flat plate units.
When pressed about the thicknesses of the various film layers, Gronet claims Solyndra "has the thinnest layers of anyone out there...the absorber layer is about a factor of 2 thinner" than competing technologies. Since the CIGS stack is generally in the 1.0 to 2.5 micron range, and you can't go too much thinner than a micron, it's likely Solyndra is achieving something slightly submicron with its coevaporation process. By using less of the active materials, the company reduces its deposition process times and thus might boost throughputs and bring down overall manufacturing costs.
As for conversion efficiencies, the CEO cites figures in the "12-14% range" for the inner cell. But he wouldn't discuss the module or panel level numbers, saying that "we don't measure efficiency at the module level" because of the widely varying "rooftop efficiencies" caused by different temperature, wind, and sun conditions. He also stressed the company's focus on the system as a whole, not the components therein.
While much of the solar industry uses "module" and "panel" interchangeably, Solyndra has instituted its own differentiating nomenclature. Forty of the tubes or "modules" are mounted in what Solyndra calls its "panel," a 1.8 meter long by 1.08 meter wide, relatively simple nonpenetrating framework that sits flat about a foot off the roof. The whole shebang weighs about 32 kg (70 lbs).
Traditionally, the total expense of installed PV comes about half from the price of the manufactured panel and half from the cost of installation. While Gronet would not disclose Solyndra's current or projected cost per manufactured watt for its modules and panels, he did tout the system's simple design, ease of installation, and superior electricity output per rooftop.
He says that customers have validated that the Solyndra racks can be installed in one-third the time of a normal flat plate PV system, at about half the cost. The panels are easy to carry, and the proprietary mount hardware can be bolted down with simple hand or power tools. It doesn't take much time to place the panels, plug in the DC connectors, and set up the ground strap. To connect one panel to another, a clip does the trick.
Each nonpenetrating system is self-ballasted. The mounting design follows the contours of the average not-so-flat flat roof, Truman told me, and allows the panels to sit over most low-lying obstructions.
A team of five workers can install about 40 KW of Solyndra panels in a day, according to Gronet, and the system is as easy to take apart as it is to put together, offering mobility and flexibility for those who might want to move the PV to another location or do some work on the roof itself.
There's a stellar view of the East Bay foothills and Solyndra's own 50-KW PV array atop the white reflective membrane-covered roof of the building next door to the CIGS fab. As you look off over the dozens of panels covering the space, the gaps between the tube modules begin to blur, especially as the sun dips lower, creating an illusion of flat-plate solidity.
Without too much imagination, one can envision acres and megawatts of tubular PV panels stretching over rooftop upon rooftop, transmitting renewable electrical juice to the buildings they perch on, while adding to Solyndra's burgeoning revenue stream.
Coming up in Part II of the blog, a tour of Solyndra's front-end manufacturing facility and more.
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