Solar Cell technologies are in continuous evolution and newer developments surprise us day by day. The Phoenix-based company RoseStreet Labs Energy has developed a prototype solar cell that combines gallium-nitride with silicon, a technology that achieves an efficiency of 25 to 30 percent.
The company CEO, Bob Forcier announced that the solution will be commercially viable in the fourth quarter of 2010, when the first cells will come out of the production lines. These solar cells will be able to convert 25-30% of the sun energy into electricity, which is a quite good percent compared to the actual technologies. Currently the most efficient silicon solar cell is provided by the Californian SunPower and has an efficiency of 22.5 percent. There are solar cells on the market with a much higher efficiency percentage but also the price of these is much more higher as they are developed mostly for satellite solar panels.
RoseStreet has found a way to increase the efficiency of silicon cells by adding a layer of gallium-nitride which, unlike silicon and other more common semiconductors used for solar cells today, can be tuned to make use of photons from a broader range of spectrum. It is possible that another semiconductor is used for this cell but there are no specifications yet.
Gallium-nitride is a very common material, mostly used for making light-emitting diodes (LED): “With gallium-nitride you can tune it for whatever [par of the spectrum] you want. It’s like a piano versus the ukulele – you get more notes with the piano. This technology allows silicon to be supercharged, like adding a big booster without a big cost penalty.”
The company will not stop here. They have some other plant to develop a product that will have at least 48% efficiency. Their new product will be based on gallium-nitride which will be probably deposited on glass or amorphous silicon.
The plan is to reach a cost of $1,5 per watt by 2014, but at this moment there is no exact disclosure of the price or manufacturing costs. This product will probably not be able to compete with silicon based solar cells because of the price but the technology can easily be used for high buildings, embedded on cars roofs or in laptop computers. The cells also could be used for concentrating solar energy systems, which use lenses to concentrate the sunlight onto cells to increase energy production.
Many companies are willing to pay more for high-performing cells because they will be able to use smaller cells to get the same amount of power. This will probably not apply to home users which can easily install their classic solar panels on the roof of their home.