A new spectral measuring station was set up at the solar test centre in Cologne for this purpose that can measure photovoltaic modules with an edge length of up to 200 centimetres. The measurements, in wavelengths ranging from 300 to 1,200 nanometres, are carried out in increments of one nanometre and are non-destructive in nature, since the module can be contacted at the terminals without interfering with the solar cell circuitry.
This saves considerable time and money when preparing testing samples and performing analyses. In addition, the modules measured can be used as high-quality calibration modules in module production, for example.
The new spectral measuring station serves to improve the precision of power measurements for photovoltaic modules, especially for thin film modules, and offers various advantages. The approximately five by five centimetre measurement area of the module surface can be freely selected, which also permits irregularities of spectral sensitivity to be examined. Stacked or multi-junction cells can also be tested.
"Manufacturers use these measurement results during development in particular, in order to optimise the design of solar modules," according to Jörg Althaus, head of the Photovoltaic Modules Qualification division at TÜV Rheinland. With multi-junction technology, the various solar cells must be optimised to a particular wavelength range in order to increase efficiency so that, overall, a broad spectrum of sunlight can be utilised.
The new spectral measuring station at TÜV Rheinland was developed by the Japanese National Institute of Advanced Industrial Science and Technology (AIST) and is one of just a few test stands of its kind worldwide. The installation was co-sponsored by the German Federal Ministry for the Environment as part of the research project for long-term sustainability and power characterisation of thin-film solar modules. In the project, suitable methods and procedures are being developed which aim to improve the precision of laboratory measurements with sun simulators for the various thin film technologies.
Thanks to the new measurement technology, the analyses now available at TÜV Rheinland serve to achieve a higher-quality calibration for crystalline photovoltaic modules and to significantly reduce the overall occurrence of measurement uncertainties during testing from plus or minus 2.5 percent to around plus or minus two percent.
The test stand for measuring spectral sensitivity as well as the new services will be presented to the public by TÜV Rheinland at the Intersolar Europe trade fair in Munich from 8 to 10 June 2011.
