Panasonic Sets New Solar Cell Efficiency Record
There are a few companies and institutes that stand out when I think of solar efficiency records. NREL, Sharp, SunPower, First Solar, Fraunhofer, and Panasonic are key ones that come to mind for me. Panasonic has lived up to its history of efficiency improvements by developing another record-breaking solar cell in the crystalline silicon-based solar cell category. The company it is knocking off the podium? Itself. Here’s more in another Solar Love repost:
Panasonic has a long history of breaking solar efficiency records. The company recently announced that it has broken an efficiency record again.
Its HIT solar cell has achieved a conversion efficiency of 25.6%, a new world record and “a major increase over the previous world record for crystalline silicon-based solar cells,” as Panasonic notes.
Notably, that previous record was also set by Panasonic. Back in February 2013, we announced that the company’s HIT solar cell had hit an efficiency of 24.7%.
“The achievement of this new record was made possible by further development of Panasonic’s proprietary heterojunction technology to realize the high conversion efficiency and superior high temperature properties of the company’s HIT solar cells as well as adopting a back-contact solar cell structure, with the electrodes on the back of the solar cell, which allows the more efficient utilization of sunlight,” the company adds. Here’s more:
Outline of the core technologies behind the record conversion efficiency
1. Reduction in recombination loss
A key feature of HIT technology is its ability to reduce the recombination loss of charge carriers, particles of electricity generated by light, through laminating layers of high-quality amorphous silicon on the surface of the monocrystalline silicon substrate, where power is generated. By utilizing the technology to form a high-quality amorphous silicon film on the monocrystalline substrate while minimizing damage to the surface of the substrate, it has been possible to realize a high temperature coefficient of -0.25% per degree Celsius which is able to maintain a high conversion efficiency even with high open circuit voltage (Voc) and at high temperatures.
2. Reduction in optical loss
In order to increase the current in a solar cell, it is necessary to lead the sunlight which arrive at the cell’s surface to the monocrystalline silicon substrate, which is the layer which generates the power with less loss. Placing the electrodes on the reverse as back contacts allows the light to reach the substrate more efficiently. This has led to a marked improvement in short circuit current density (Jsc) to 41.8mA/cm2 over Panasonic’s
previous figure of 39.5mA/cm2 (in the case of a cell with a conversion efficiency of
24.7%).
3. Minimizing resistance loss
In solar cells, the generated electrical current is accumulated in the surface grid electrodes and output externally. Previously, the grid electrodes on the light-receiving side were optimized by balancing the thickness of the grid electrodes (thinning the grid electrodes to reduce the amount of light blocked) and the reduction of electrical resistance loss, but by placing the electrodes on the reverse side, it has become possible to reduce the resistive loss when the current is fed to the grid electrodes. In addition, a high fill factor (FF)*13 of 0.827, has been achieved, even at a practical cell size by improving resistance loss in the amorphous silicon layer.
Of course, Panasonic isn’t done. It intends to break this record some day as well.
Image Credit: Panasonic
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“There are a few companies and institutes that stand out when I think of solar efficiency records. NREL, Sharp, SunPower, First Solar, Fraunhofer, and Panasonic are key ones that come to mind for me.”
Add Solar Frontier (CIS), Stion (CIGS), Siva (CIGS), Trina Solar (silicon), Oxford PV & EPFL (perovskite) for me.
I wouldn’t call NREL a company. but otherwise.
was considering it an institute, but maybe not entirely accurate either.
Doesn’t matter. Sort of is… It’s huge and your thinking is right on.
Can anybody explain the difference between Panasonic’s “heterojunction” technology, with a layer of amorphous silicon assisting a noncrystalline generating layer but not apparently generating itself. and the true two-junction cells a lot of labs are working on?
A 0.9% gain in efficiency (proportionately 3.6%) in 13 months is impressive. Since Panasonic are a large-scale manufacturer, their advance is more likely to trickle down into production panels in the near future than equal gains in independent research labs. They wouldn’t bother with hero techniques that can’t possibly get into mass production.
According to PVinsights, http://www.pvinsights.com, there are a new technology with 24% cell efficiency and the much cost competitive to HIT technology.