Articles you may be interested inPhotoreflectance and contactless electroreflectance measurements of semiconductor structures by using bright and dark configurations Rev. Sci. Instrum. 80, 096103 (2009); 10.1063/1.3213613 Temperature dependent surface photovoltage spectroscopy characterization of highly strained InGaAs/GaAs double quantum well structures grown by metal organic vapor phase epitaxy Determination of band offsets in semiconductor quantum well structures using surface photovoltage J. Appl. Phys. 94, 3955 (2003); 10.1063/1.1603346 Differential surface photovoltage spectroscopy characterization of a 1.3 μm InGaAlAs/InP vertical-cavity surfaceemitting laser structureMeasurements of electroreflectance and surface photovoltage spectroscopy of semiconductor structures are described using a transparent indium-tin-oxide-coated glass electrode in soft contact mode on the semiconductor surface. This improvisation ͑simplification͒ reduces the magnitude of the ac modulation voltage necessary for the electroreflectance measurement to less than a volt from about a kV ͑ϳ10 3 V͒ as required in the conventional contactless setup. This soft contact mode also enhances the sensitivity of the surface photovoltage signal by three orders of magnitude. We also formulate an analytical criterion to extract the transition energies of a quantum well from the surface photovoltage spectrum.

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The All India Survey of Photovoltaic Module Reliability 2014 is an enhanced version of the survey conducted in the previous year, with detailed characterization of PV modules including current-voltage, infrared and electroluminescence imaging, visual inspection, insulation resistance test and interconnect breakage test. More than a thousand modules were inspected in the field and the main results of the survey are presented in this paper. The average P max degradation rate for the so-called 'good' modules (Group X) is 1.33%/year which is higher than that commonly projected by manufacturers, and widely employed in financial calculations. Modules falling in the 'not-so-good' category (Group Y) show even higher degradation rates, and it is at least partly due to higher number of micro-cracks in the modules, and increased degradation of the packaging materials like encapsulant, backsheet, etc. Modules in 'Hot' climates degrade faster than modules in the 'Non-Hot' climates. Degradation in fill factor is the primary cause for performance degradation in the young modules (ages <5 years), whereas short-circuit current degradation is the main contributor to power degradation in the older modules. Small installations (<100 kW p capacity) show higher degradation than large systems, which may be partly due to lack of proper due diligence by the owner at the time of procurement and installation.

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