Researchers Prove Silicon-Based Solar Efficiency of 36%

A collaborative effort has demonstrated a theoretical silicon-based solar cell efficiency of about 36% (at an affordable price point). The research tandem of the U.S. Department of Energy's National Renewable Energy Laboratory (NREL), the Swiss Center for Electronics and Microtechnology (CSEM), and the École Polytechnique Fédérale de Lausanne (EPFL) presented their findings in a paper, "Raising the One-Sun Conversion Efficiency of III-V/Si Solar Cells to 32.8% for Two Junctions and 35.9% for Three Junctions."

Prior to this point, and as noted by Phys.org, solar cells composed entirely of materials in Groups III and V of the Periodic Table have been prohibitively expensive (even if highly efficient).

"This achievement is significant because it shows, for the first time, that silicon-based tandem cells can provide efficiencies competing with more expensive multijunction cells consisting entirely of III-V materials," noted Adele Tamboli of NREL. "It opens the door to develop entirely new multijunction solar cell materials and architectures."

Existing single-junction silicon solar cells reach efficiencies of 17-24%, while the new GaInP/GaAs tandem cell achieves 35.9% efficiency. This is significant not only for the implicit energy savings but the cost of ownership for John Q. homeowner.

As it stands, solar cells cost somewhere from 20-40% of the overall photovoltaic system, making it (and the “break-even point”) a very long-term investment. But with solar efficiencies north of 35%, the system cost could drop by approximately 45 cents per watt.

Read the full report here: https://www.nature.com/articles/nenergy2017144