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Solar Cells

Working Group 4.52

Profile

The "Solar Cells" Working Group is responsible for the dissemination of radiometric units in the field of photovoltaics. An essential point here is the primary calibration of reference solar cells by determining their short-circuit current under standard test conditions ISTC and their absolute spectral irradiance responsivity. For this purpose, the temperature coefficient and the linearity of these quantities are also measured. Optionally, the I-V characteristics of the reference solar cell and its spectrally and polarization-resolved angular dependence can be measured with the highest precision.
In the field of R&D, the working group deals with the primary calibration of reference solar cells for space applications, with the development of more exact outdoor calibration methods and with the characterization of solar simulators. At the national and international level, the standardization activities are focused on the series of standards DIN EN / IEC 60904 (photovoltaic devices) and DIN EN / IEC 61853 (energy rating).

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Research/Development

  • Research and development for the primary realization of the spectral irradiance responsivity of detectors, such as solar cells, photometers and filter radiometers
  • Use of lasers for the even more exact calibration of solar cells
  • Research and development for the primary calibration of reference solar cells for space applications, in particular of component cells and multi-junction cells
  • Close cooperation with industry with the aim of transferring the developed methods and the findings obtained to applications in industry
  • Realization and maintenance of the World Photovoltaic Scale (WPVS) by regular international comparisons
  • Research for standards which are more close to reality for the assessment of solar modules

Selection of on-going projects:

  • EURAMET: EMRP ENG 55 "Towards an energy-based parameter for photovoltaic classification (PhotoClass)" http://photoclass.ptb.de
  • EURAMET: EMRP ENG 51 "Metrology for III-V materials based high efficiency multi junction solar cells (SolCell)" http://projects.npl.co.uk/solcell
  • EURAMET: EMRP ENV 59 "Traceability for atmospheric total column ozone (ATMOZ)" http://projects.pmodwrc.ch/atmoz/index.php
  • BMWi: MNPQ project "Procedures for the traceability of flasher-calibrated solar cells and modules in the industrial environment"
  • BMWi: MNPQ project "Characterization and optimization of an LED-based solar simulator for industrial applications"

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Services

  • Calibration of the absolute spectral irradiance responsivity of solar cells, photometers and (filter) radiometers in homogeneous radiation fields in the wavelength range from 210 nm to 1.9 µm
  • Calibration of the short-circuit current under standard test conditions of reference solar cells with the smallest measurement uncertainty worldwide of 0.5 %.
  • Calibration of component cells for multi-junction space cells with 3 or 4 pn-junctions.
  • Precision I-V-characteristics of reference cells (measuring duration per set of characteristics at different irradiances and temperatures: 8 hours)
  • Determination of the (non-)linearity and of the temperature coefficient of short-circuit currents under standard test conditions and of the spectral responsivity of solar cells.
  • Dependence of the solar cell current on the angle of incidence for white light as well as for different monochromatic lines and polarization directions

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Information

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