The Environmental Journal of Southern Appalachia

Displaying items by tag: gallium arsenide

Close-up photograph showing the top and bottom of two solar cellsThe rainbow colors show the diffraction of sunlight by a mirror with a nanostructured grating, which was applied to the back of the silicon subcell. The sun’s spectrum is thus captured even better in the silicon bottom cell.  © Fraunhofer ISE / Photo: Michael Schachtner
 
Fraunhofer Institute for Solar Energy Systems: Tandem Photovoltaics Enables New Heights in Solar Cell Efficiencies – 35.9 % for III-V//Silicon Solar Cell

The photovoltaic (PV) solar panels most commonly used for commercial applications today have an efficiency in the range of 16 to 22 percent. On the lower side of this range, one finds less-expensive panels, mostly made with poly-crystalline solar cells, while monocrystalline cells dominate the upper side.

The highest-efficiency panel presently on the market is SunPower’s A-Series residential panel, with a claimed 22.8 percent efficiency in converting photons to electrons under standard conditions. That's up just slightly by 0.73 percent from five years ago. Although many other manufacturers have caught up to offer panels rated at more than 21 percent, development progress of silicon-based monocrystalline PV toward the theoretical limit of around 30 percent has slowed to a crawl.

Over the same period, newer technologies for multijunction PV cells with thin subcell layers of gallium-arsenide and similar semiconductors, grown on top of silicon or perovskite crystalline materials, has been progressing rapidly and may be capable of exceeding 50 percent efficiency in the future. Lab results still require years of research and manufacturing development before panels come to market. Initially their high price will limit them to market niches where low-weight and small-surface per Watt will justify the cost, such as for aerospace applications or covering electric vehicle surfaces. The following links provide a good overview of such technologies and discuss their longer-term outlook.

DOE Energy Efficiency & Renewable Energy: Multijunction III-V Photovoltaics Research
Frauenhofer ISE: Tandem Photovoltaics – The Road to Higher Conversion Efficiencies
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