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Numbers game: Thin-film solar PV enigma OptiSolar peeks out from behind the curtain

05 December 2008 | By Tom Cheyney | Chip Shots

optisolar_arrayGov. Arnold Schwarzenegger used OptiSolar's Sacramento module-manufacturing factory as the scene for his recent announcement of an executive order streamlining California's renewables project approval process and increasing the California's renewable energy standard to 33% by 2020, an ironic backdrop given the company's semistealthy reticence to talk much about its manufacturing processes and capabilities.

The press release about the executive order made mention of the new OptiSolar plant, saying it "will begin manufacturing solar panels in early 2009. When fully built out," the PR continued, "the one-million-square-foot plant will be the largest photovoltaic solar panel manufacturing plant in North America, providing 1000 green jobs and producing approximately 2000 solar panels per day." That 2000 breaks down to about 83 panels per hour, assuming a 24-hour production modus operandi.

During his introduction of the governor at the event, company CEO Randy Goldstein (with an array of OptiSolar modules on the rooftop behind him) mentioned that the factory will have a production capacity of "several hundred megawatts per year." He also reiterated the company's plans to build the Topaz solar farm--one of the largest in the world at 550 MWp, when fully developed--on the Carrisa Plains in the Central California county of San Luis Obispo. The installation will eventually provide an impressive 1.1 GW of PV power that Pacific Gas and Electric will buy and supply to its customers.

Since the company won't, or at least hasn't yet, divulged many specifics about its amorphous-silicon thin-film PV modules, such as their wattage/capabilities or how they are made (though patent searches reveal a combo of CVD and PVD processes), I ran the few numbers that are floating in the cyberether--including those cited by the Governator--and tried to make sense of them.

For example, in a May 2007 press release about plans for the company's OptiSolar Farms Canada subsidiary to install a pair of 10 MW solar farms in Petrolia, Ontario, Canada, it was said that "OptiSolar Farms will install over 600,000 ground-mounted solar panels." With a quick back-of-the-envelope calculation, dividing those 600,000 panels into that total of 20 million watts for the two Ontario sites, the quotient is a guestimated approximate wattage of 33.3 watts per panel.

When that 33.3 W is mulitplied by the 2000 panels per day number cited in the governor's PR, the product is 66.6 KW; if that 66.6 gets multiplied by 365 for a mythical annual output figure, the answer is 24.3 MW--a long way off from the several hundred megawatts cited by OptiSolar's Goldstein or the figure of "over 600 MW" posted on the company's Website.

Perhaps a zero here and there were left out, unintentionally or not. In any case, the numbers just didn't add up.

optisolar_fabSo to try and get this incomplete data set to make sense, I reached out to Alan Bernheimer, OptiSolar's VP of communications. Although he did answer my email (that comes with the communicating part of his gig), his reply was very sparing in its details.

"We're still largely quiet," he explained, "with occasional exceptions like the PG&E announcement in August and the Governor's recent appearance."

"What we've said publicly about production capacity is that the high-volume plant in Sacramento will produce more than 600 MW per year of solar panels when it is fully built out in several years," he continued. "And yes, 2000 panels per day would be at the low end of our projected output range. Don't forget what we call a panel is composed of 12 modules, attached to a frame in a 3 x 4 array."

"Our initial manufacturing lines in Hayward are currently supplying panels being installed in Sarnia, Ontario, but we haven't specified the production capacity here. (Blogger's note: An NREL table on TFPV capacity puts the Hayward plant's capacity at 40 MW.) Also, we haven't specified our panel output wattage."

Despite Bernheimer's comment about how the company defines panels and modules, there's still some latent confusion about OptiSolar's nomenclature. In the aforementioned 2007 press release about the PV farms in Ontario, the specific term used was "solar panels," not modules. If we take the company's definition of panel , as stated by Bernheimer, then 600,000-plus panels are equivalent to 7.2 million modules. This really doesn't make sense, since that would mean the modules would each be rated at 2.77 watts or so--well below any sensible power metric.

Perhaps the TFPV mystery house didn't have its own terminology nailed down last year. If that's the case, and those 600,000 so-called panels were indeed modules, then perhaps my earlier calculations are closer to reality: with a dozen modules per panel, at 33.33 watts per module, that means OptiSolar's panel array packs about a 400-W punch.

Let's extrapolate to the production side, using OptiSolar's definition of panel. Even at the low output end of 2000 400-W panels per day (or 24,000 modules, or a thousand per hour), that's 800 KW of daily production and 292 MW of theoretical annual nameplate capacity.  With performance tweaks and continuously improving production efficiencies combined with capacity expansion, one can easily imagine OptiSolar reaching that 600-MW-plus production number down the line.

Putting my calculator aside, I asked Bernheimer in a follow-up email for some guidance on when OptiSolar plans to open its proverbial stealth-kimono and offer more transparency about its technology, production status, and panel specs.

His reply: "No kimono predictions, but let's stay in touch."

Still, don't be surprised if 2009 is the year that OptiSolar comes out into the light.

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