A characterization study of ultrasmall ultraefficient multijunction concentrator solar cells is presented, with emphasis on performance sensitivity to light intensity and distribution. Information of this type is essential in the design and optimization of the latest generations of high-flux photovoltaic systems. Cell miniaturization allows increasing the concentration at which efficiency peaks, facilitates passive heat rejection, and permits the use of all-glass optics. However, few device measurements have been published on ultrasmall cells. Extensive measurements, up to ∼5000 suns, on the 1.0mm2 active region within the busbars are reported and analyzed.

Metal fingers typically cover more than 10% of the active area of concentrator solar cells. Microfabricated dielectric optical designs that can completely eliminate front contact shading losses are explored. Essentially no microconcentrator optical losses need be incurred, series resistance losses can be reduced, and net efficiency gains of roughly 15% (relative) are realistic.

Essentially loss-less all-dielectric micro-fabricated optics can be tailored to completely eliminate the shadowing losses metallization grids create on the surface of concentrator solar cells. The nonimaging micro-concentrator exploits total internal reflection to redistribute the elevated flux from available macro-concentrators, rather than increasing overall concentration. The optical designs permit widening the metal fingers toward lessening series resistance losses, which can also finesse the need for the intricate metallization patterns of some high-flux cells. Realistic net efficiency gains of 15% (relative) are achievable in a wide variety of concentrator cells. Downloaded From: http://proceedings.spiedigitallibrary.org/ on 06/24/2016 Terms of Use: http://spiedigitallibrary.org/ss/TermsOfUse.aspx Proc. of SPIE Vol. 6651 665103-3 Downloaded From: http://proceedings.spiedigitallibrary.org/ on 06/24/2016 Terms of Use: http://spiedigitallibrary.org/ss/TermsOfUse.aspx

We present an experimental characterization study of high-efficiency ultra-small multi-junction concentrator solar cells. Particular emphasis is placed on the sensitivity of photovoltaic performance to the intensity and distribution of the concentrated sunlight delivered to the cell. This type of information is important in the design and optimization of the most recent generations of high-concentration photovoltaic systems. Miniaturizing the solar cell can give rise to an increase in the concentration value at which cell efficiency peaks, facilitates passive heat rejection and permits the use of all-glass optics. However, few measurements have been published for ultra-small cells. We report and analyze extensive measurements, up to approximately 5000 suns, on the 1.0 mm 2 active region within the busbars of such commercial concentrator solar cells.