Mark W. Wanlass

Empirical procedure to correct concentrator cell efficiency measurement errors caused by unfiltered xenon flash solar simulators

In this paper, we present an empirical error correction procedure for efficiency measurements of series-connected, multijunction concentrator solar cells. The error arises from the use of unfiltered xenon flash solar simulators with excess infrared radiation (wavelengths > 900 nm) into lower-bandgap subcells, and always results in an artificial increase of the measured efficiency. The efficacy of the procedure is demonstrated by comparing unfiltered efficiency data against other data from a flash simulator in which the spectral irradiance was properly adjusted.

Concentrator cell efficiency measurement errors caused by unfiltered xenon flash solar simulators

In this paper, we present an empirical error correction procedure for efficiency measurements of series-connected, multijunction concentrator solar cells. The error arises from the use of unfiltered xenon flash solar simulators with excess infrared radiation (wavelengths > 900 nm) into lower-bandgap subcells, and always results in an artificial increase of the measured efficiency. The efficacy of the procedure is demonstrated by comparing unfiltered efficiency data against other data from a flash simulator in which the spectral irradiance was properly adjusted.

0.74/0.55-eV Ga/sub x/In/sub 1-x/As/InAsP/sub 1-y/ monolithic, tandem, MIM TPV converters: design, growth, processing and performance

Thermophotovoltaic (TPV) tandem converter technology is being explored in an effort to improve both the efficiency and power density of TPV systems. Inverted, tandem structures incorporate epitaxially grown 0.74-eV lattice-matched Ga/sub 0.47/In/sub 0.53/As and 0.55-eV lattice-mismatched Ga/sub 0.28/In/sub 0.72/As diodes. Additionally, a strategy has been developed to allow voltage matching between these two subcells. Performance modeling calculations show that, under typical operating conditions, the 0.74/0.55-eV tandem converter should outperform a 0.5-eV single junction converter by 15% on an efficiency basis and by 15% on a power-density basis. This paper will present details regarding the design, growth, fabrication, and electrical, optical, and structural characterization of voltage-matched tandem TPV devices.