A new breakthrough in the design of silicon-based solar cells has seen a 20-year-old efficiency record broken by not one, but three companies. Presenting at the IEEE Photovoltaic Specialists Conference in Denver, Panasonic unveiled its latest record-breaking design, with Sharp and SunPower also presenting new models that surpassed previous efficiency benchmarks. The breakthroughs pave the way for solar power to compete commercially against fossil fuels.
The chief difference in the new designs seems kind of obvious upon reflection: traditional silicon solar cells have their positive contacts on the face of the panel, which effectively shade parts of the panel, reducing the efficiency of the unit as a whole. By transferring the contacts to the reverse of the panel where the negative contacts are, as explained by SunPower cofounder Richard Swanson in the YouTube video above, the new designs resolve this issue.
Panasonic gets the edge on its two competitors by virtue of the greater efficiency of its current silicon solar cell design. Silicon solar cells make up the vast majority of solar cells on the market today. In most silicon cells, electrons are trapped by the surface imperfections in the crystalline silicon wafers in the cells. This decreases the current and voltage generated. To avoid this issue, Panasonic adds thin films of silicon to the front and back of each wafer.
Panasonic’s new cell design achieves a conversion rate of 25.6 percent of the sun’s energy into electricity. Sharp’s and SunPower‘s designs also achieved efficiencies of greater than the previous record of 25 percent. While on paper the results don’t seem like a great gain, they are quite a significant breakthrough in terms of the final power output of the unit. The University of New South Wales‘ Professor Martin Green, designer of the previous record-holding cell, points out that the new designs use a more expensive, high-quality silicon crystal than the cheaper grade of silicon currently in use. However, the new design prototypes, not yet ready for commercial production, open the way for further efficiency improvements, which are anticipated to reduce the final cost to the consumer.