The past month has brought good news and bad news for thin film solar enthusiasts. In May, Chinese giant Hanergy Thin Film’s stock took a mind-boggling dive. Meanwhile, this week, First Solar has set a world record for cadmium telluride thin film solar module efficiency, hitting 18.6 percent aperture efficiency.
Thin film solar cells have been used in small-scale applications since the 1970’s for consumer electronics beginning with calculators, and more recently appearing on solar yard lights, emergency radios and cell phone chargers. Thin film technology has been scaling up to larger applications, now competing with conventional crystalline silicon (c-Si) panels. Commercially available thin film panels are made of cadmium telluride (CdTe), copper indium gallium diselenide (CIGS), and amorphous and other thin-film silicon, unlike conventional solar c-Si cells. Thin film panels are cheaper and flexible, making them more versatile than their rigid c-Si competitors, but the big stumbling block is their lower efficiency. This means that it take a larger area to produce the same energy as a c-Si panel.
Early in the 2000’s thin film panels were the talk of the solar industry. Giant corporations like British Petroleum invested heavily in the promise of thin film. Thin film startups promised that efficiency comparable to conventional solar cells was just around the corner. Unfortunately the promises just didn’t materialize quickly enough for many solar speculators, and despite a spike in sales of thin film during a shortage of c-Si panels in 2010, the overall share of the solar market held by thin film continues to remain flat– below 10%.
BP dropped thin film in 2003, before it got out of the solar business altogether in 2011. Also in 2011, Solyndra, a manufacturer of a cutting edge thin film technology, suffered a high-profile collapse, further sullying the reputation of thin film products. Now, Hanergy Thin Film, and its parent company Hanergy Holdings are in the midst of a complete meltdown. The Securities and Futures Commission has announced its plan to investigate Li Hejun, Hanergy’s founder and chairman. It has been a tough five years for thin film, to say the least.
Despite Hanergy’s claims of huge efficiency upgrades, their technology appears to be vaporware. However, the last two heavy hitters in the thin film world– First Solar and Solar Frontier– appear to be in an all-out race to the top. Solar Frontier, a Japanese company, set the aperture efficiency record at 17.8 percent late in 2012. This month, American manufacturer First Solar topped that record, hitting 18.6 percent. Raffi Garabedian, First Solar’s Chief Technology Officer stated that: “First Solar’s CdTe thin film is now rightly categorized as a high performance product. At one time, we might have been characterized as a low cost, low efficiency technology, but consistent with our technology projections we are now proving that CdTe thin film delivers both industry-leading performance AND sustainable thin-film cost structures.”
So where is thin film headed? In a recent article in Renewable Energy World entitled “7 Reasons Thin Film Is Alive and Set to Win in Solar”, author Brad Mattson, CEO of Siva Power wrote: “Developments in the past six months indicate that thin film is not only experiencing a revival, it is positioning itself for a run at silicon. The world’s largest solar panel power plant? 290 MW of thin film. Solar charging stations for Tesla in China? Thin film. Record for the world’s highest efficiency solar panel? Thin film. Biggest solar project planned in Africa at 400 MW? Thin film.”
Although Mr. Mattson’s outlook may be overly optimistic, he makes a valid point, and that is, thin film is finding its niche, and it is not competing with silicon panels for residential use. Large installations where space is not a factor, or in Building Integrated Photovoltaic (BIPV) applications. Despite the recent roller coaster ride, thin film appears to be moving up.
