A solar thin-film efficiency first

First Solar has cracked the 20 per cent efficiency mark for the cheaper and lighter, and therefore more commercially flexible, thin-film solar cell.

CleanTechnica

This one really knocked our socks off. The last time we checked in on First Solar was almost exactly one year ago, when the company announced a world solar cell efficiency record of 18.7 per cent for its thin film solar technology. Now it has crushed its own record, cracking the 20 per cent barrier with a new world record of 20.4 per cent.

That might sound like peanuts compared to conventional silicon solar cell efficiency, which has skyrocketed up into the 40 per cent range, but solar conversion efficiency is only one factor in the installed cost of solar power.

Thin film has some key advantages including low manufacturing costs, and its characteristic flexibility and light weight lend it to both portable and stationary applications.

Yet another solar cell efficiency record for First Solar

First Solar got all its ducks in the water before making its new solar cell efficiency announcement. The 20.4 figure was confirmed by the US National Renewable Energy Laboratory and certified at Newport Lab (not to be confused with a number of other facilities with similar names).

The new record is the result of a collaborative research partnership that First Solar formed last April with GE, which had previously set a record of 19.6 per cent for its thin film solar cell.

Both companies had been developing thin film technology based on cadmium telluride (CdTe), a crystalline compound of the silvery bluish metal cadmium and tellurium, a brittle metalloid.

With the new announcement, First Solar chief technology officer Raffi Garabedian really got up in the silicon solar cell industry’s grill. At 20.4 per cent, the CdTe conversion efficiency matches that of multicrystalline silicon and here’s what Garabedian had to say about that:

"We are demonstrating improvement in CdTe PV performance at a rate that dramatically outstrips the trajectory of conventional silicon technologies, which have already plateaued near their ultimate entitlements.
"The synergy realised in our partnership with GE also demonstrates the value of our consistent and strong investment in R&D. The advanced technologies and processes we developed for this record-setting cell are already being commercialised and will positively impact performance of our future production modules and power plants."

For the record, we’re also following a company called Empa, which has been developing a sort of upside-down CdTe thin film solar cell that could eliminate a costly part of the manufacturing process. So far its CdTe cell is down in the 11 per cent efficiency range so it still has some catching up to do.

We built this thin film CdTe solar cell!

CdTe thin film has been a hot area of research partly because it is conducive to high volume commercial production, unlike some more efficient but more quirky and exotic materials.

According to NREL, off-the-shelf bulk cadmium telluride is readily available in the form of a powder that can be reconstructed into thin film form. The relative simplicity of the compound is another plus.

NREL has been working with industry partners since 1994 to addressing the key challenges involved in ramping up thin film technology to commercial viability through its Thin Film Photovoltaic Partnership Project, which counts First Solar among its partners.

At the manufacturing end, those challenges include the development of buffer layers that can tolerate the high heat required to deposit CdTe onto a substrate. NREL has also been instrumental in developing an understanding of the fail factors in CdTe solar cells, which is a necessary first step to engineering more durable and long-lasting devices.

First Solar’s relationship with NREL dates at least as far back as 2003. For those of you keeping score at home, that’s the Bush Administration.

All together, thanks to those partnerships the US thin film industry grew from a manufacturing capacity of just 10 MW in 2003 to a whopping 250 MW by the time President Bush completed his second term in office, in 2008.

However, cross-party support for foundational solar R&D at the presidential level hasn’t stopped Republican leadership in Congress from trying to kick the legs out from under First Solar during the Obama Administration.

In one of many investigations that appear to have gone nowhere, in 2011 House Oversight and Government Reform Committee Chairman Darrell Issa (R-CA) accused First Solar of not being innovative enough to qualify for Energy Department loan support, although he was not shy about requesting funds through the same loan program for a campaign contributor.

On the other hand, there seems to be a pro-solar movement bubbling up among the Republican rank and file, as property owners across all party lines cotton to the idea of harvesting — and in many cases, selling — their own solar power, so stay tuned for more on that.

Originally published on CleanTechnica. Reproduced with permission.

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