PHOTO: Gehrlicher Solar via IEEE Spectrum
The quest for inexpensive solar panels continues, with cadmium telluride generating enthusiasm among investors and hopeful followers of the advance of alternative energy technologies. Over at IEEE Spectrum, Richard Stevenson speculates that First Solar might beat over 80 competitors to achieve manufacturing costs low enough to market solar panels at less than $1 per Watt, the target considered necessary for solar to compete with coal-burning electricity on the grid. Tempe, Arizona, based First Solar's main market currently is Germany, where government policies promote solar power growth.Cadmium Advantages in Solar Panels
With silicon supplies under pressure after rocketship market growth, alternative photovoltaic technologies can wedge into the competition. Cadmium has several advantages over traditional silicon technology. These include:
- The necessary electric field, which makes turning solar energy into electricity possible, stems from properties of two types of cadmium molecules, cadmium sulfide and cadmium telluride. This means a simple mixture of molecules achieves the required properties, simplifying manufacturing compared to the multi-step process of joining two different types of doped silicon in a silicon solar panel.
- Cadmium telluride absorbs sunlight at close to the ideal wavelength, capturing energy at shorter wavelengths than is possible with silicon panels
- Cadmium is abundant, produced as a by-product of other important industrial metals such as zinc.
Cadmium telluride drawbacks
Cadmium telluride solar panels currently achieve an efficiency of 10.6%, which is significantly lower than the typical efficiencies of silicon solar cells, quoted as 16% in Stevenson's article. This makes the necessity of lowering the cost per square foot critical.
Environmental Issues of Cadmium
Concerns that risks of cadmium telluride in solar photovoltaic film have been raised. TreeHugger Forums commenter green Wind Power Fan makes reference to an article noting that few manufacturers are producing cadmium telluride solar panels which pass the US EPA's leaching test, a process used to determine whether toxic metals, such as cadmium, might seep out into groundwater from improperly disposed waste.
But solar panels have relatively long lifespans, measured in decades. This means that laws like the European ban on cadmium in electronic gadgets are less necessary, because the benefits of a long lifespan outweigh the managed risks of using cadmium telluride. Furthermore, recycling at end of life will minimize risks. First Solar already plans for the take-back of solar panels they sell today, after a 25 year lifespan.
More on Cadmium Telluride Solar Panels
The Challenge And Opportunity Of Cadmium Telluride, Solar Photovoltaic Film
New Solar Panels Produced at Less Than $1 Per Watt
Update: If you are interested in solar power, also check out 15 Photovoltaics Solar Power Innovations You Must See.