Solar energy and 'going green' are getting a lot of attention these days. Many people are talking about thin film solar cells, also called solar film. This article will give you a rundown on the various technologies out there, without getting too deep into the chemistry and physics of how they work.
Solar film cells are getting a lot of attention because they address the biggest issue with solar energy: cost. The development of this technology has take great strides in recent years because they are cheaper to manufacture than traditional solar panels. Thin film solar panels are what you would find in a solar calculator, and this technology is being expanded into panels for large residential and commercial use. Global Solar Energy, for example, recently installed a 750 kilowatt array that provides 25% of factory's power needs.
There several technologies that exist that fall under the solar film heading:
1. Amorphous or Thin Film Silicon. This technology uses the same science that is found in the rectangular solar panels we are seeing more and more of in the world. Instead of using hard crystalline silicon that must be encased in tempered glass and aluminum frames like normal solar panels, the silicon is deposited on a flexible piece of metal or plastic and then coated. This technology is generally less efficient, but much cheaper to make. To produce the same amount of energy as a traditional solar panel, you would need 30-50% more surface area of thin film silicon solar.
2. Cadmium Telluride. This technology is less popular than thin film silicon for several reasons. While it is more cost-effective to manufacture, it is less efficient than silicon. Additionally, the materials in these cells tend to be toxic, leading to concerns about the manufacturing process and the long term environmental effects of the cells. Studies are being done as we speak to investigate the long term toxicity of cadmium telluride since the economics of the technology are very attractive. Typical efficiencies for these cells are around 15%. This means that 15% of the total energy that fell on the cell was converted to electricity.
3. CIGS. CIGS is an acronym for'copper indium gallium (di)selenide' (see why we call it CIGS?). CIGS cells have the most promise for bringing down the cost of solar since the economics AND efficiencies are very promising. In 2005, the National REnewable Energy Lab achieved a world record 19.9% efficiency for a CIGS cell. This means that 19.9% of the total energy that fell on the cell was converted to electricity. This is approaching the world record for a common solar panel of 24.7%. This very exciting because manufacturers anticipate the cost of mass-produced thin film cells to be around $1.00/watt. Common silicon solar panels we are used to seeing are close to $5.00/watt. Companies such as Shell, Nanosolar, and Honda are investing heavily in this technology. Nanosolar is particularly interesting in that is has the backing of Silicon Valley venture capital and the Google founders. They are in the process of building a massive manufacturing facility and claim that they will produce solar cells at 1/10th the cost of current cells. Very exciting.