What Are Thin Film Solar Cells?
This year has been busy so far visiting customers and attending a number of Trade Shows around the world and to my surprise, albeit based on a limited number of direct conversations with various technical personnel associated with a number of different companies, I have found that the thin film photovoltaic market is far from dead. I personally had thought that, if not dead, it was certainly dying a slow death. I am very pleased to have been proven wrong.
One of the world leaders in Thin Film Modular Technology, First Solar, has now manufactured and installed over 10 gigawatts (GW) of worldwide energy photo voltaic (PV) power plants producing electrical energy products utilizing their own brand of proprietary sputtered thin film technology. That is a tremendous amount of alternative energy feeding worldwide electrical grids of renewable clean energy cost effectively. First Solar’s PV solar energy is based on a cadmium telluride (CdTe) technology that has a theoretical efficiency (electrons/photons) of 30%. In laboratory test modules First Solar has shown sustainable efficiencies of over 20%. This leaves a significant range for improvement and First Solar has done just that – adding roughly a half a percent per year over the past 10 years by further improving and investing in the overall research and development of their various product lines. The present CdTe efficiencies over large areas are approximately 10% greater than conventional single or polycrystalline silicon technology. This is a substantial difference from the stagnant numbers of the more mature markets of photo voltaic production plants utilizing conventional crystalline silicon technologies. Commercial solar panel modules utilizing these silicon technologies have not shown any significant increases in overall production efficiencies in a quite a number of years now.
What may be even more exciting is the vast range of other technological advances being made through research firms and universities throughout the world. Talking with the various professors, students and independent research scientists at the Trade Shows has been very interesting and personally stimulating as they describe their collective technological advances and works. There is still a vast amount of time and money being spent on the investigation of a whole new class of thin films that will hopefully leapfrog the current technologies and provide cost effective alternative energy solutions compared to not only crystalline silicon technology but to fossil fuel sources as well. Thin film Solar Cells offer the lowest carbon footprint of any existing power service generation technology when taking both the production and operating figures into consideration.
The rising interest in what is being referred to as “Third generation photovoltaic cells” include thin film technologies utilizing Copper Indium Gallium Diselenide (CIGS), hydrogenated fluorinated amorphous silicon (a-Si), Copper Zinc Tin Sulfide (CZTS), Gallium Arsenide (GaAs) -which has shown a 28.8% efficiency research cell; and numerous other combinations of semiconductor based multi layered devices is all very exciting in that they all show promising efficiencies in what looks to be the future of the PV industry for alternative energy sourcing. The National Renewable Energy Laboratory (NREL) of the United States has also been developing a next generation of thin film technologies utilizing organic based or organomettalic based compounds. Panasonic has also recently shown prototype efficiencies on Si materials of 25.6%.
There is still a lot of work to be done in commercializing the state of the industry, but, contrary to my prior belief that the Thin Film Solar Energy Industry was dying a long and painful death, the future looks bright as the historically developed technologies have developed into mature industries and future work on the development of new materials looks more promising than ever. Sometimes it’s really nice to be wrong.
