posted on September 12, 2013 |
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Solar3D, a US photovoltaic cell manufacturer, received an international patent for its 3D solar cell technology. Solar3D’s earlier prototype set a record for silicon PV cell efficiency, reaching 25% in 2012. The company expects its newest version to be better and less expensive to manufacture.
A standard PV cell includes two semiconductor layers: P and N. The layers are flat and stacked one on top of the other. In simple terms, when a photon strikes an electron, it adds energy to the electron. If all goes well, the electron gains enough energy to jump over the PN junction, causing current to flow. The problem is that not all photons collide with electrons - some are simply absorbed into the cell and generate heat - not what you want.
The theory behind Solar3D’s design is that the trenches provide more surface area for photons to hit electrons. If a photon misses an electron, it will reflect and potentially hit another one somewhere else. Of course the photon loses some energy with each bounce. Solar3D says that after three or four reflections, the energy is negligible. Still, that’s three to four more opportunities to generate a free electron.
A side benefit of this design is that the panel doesn’t need to face the sun directly. Sunlight coming in from different angles will also hit somewhere inside the trenches. This could reduce the need for tracking, or at least make fixed-mounted panels more productive. Others have done something similar at the panel level, with good results.
Solar3D is also working to reduce the internal resistance of the cells, increasing efficiency that much more. Combined with a decrease in manufacturing costs, this cell could give a solid boost to the photovoltaic industry.
If you want to analyze the physics behind this PV cell, I encourage you to read the patent application.