Maximum Uncertainty of 1.8 Percent Precision measurements verify power output of PV solar modules

Photovoltaics plays a key role in the energy transformation to renewable energy sources and is experiencing historical success worldwide.

June 11, 2012

The CalLab PV Modules of the Fraunhofer Institute for Solar
Energy Systems ISE has further improved the accuracy of its
precision measurements on photovoltaic solar modules.
Belonging to the best worldwide, its precision testing with a
measurement uncertainty of only 1.8 percent enables the
manufacturer to exactly determine the PV module power.
For investors, this increases both the reliability and the
calculation certainty.

Photovoltaics plays a key role in the energy transformation to
renewable energy sources and is experiencing historical
success worldwide. At the end of May 2012, the level of
solar electricity production in Germany reached more than
22 gigawatts for the first time, corresponding to the
electricity production of almost 20 nuclear power plants.
Currently the worldwide installation of photovoltaics is at 60
GW, with a sharp rising trend. In this fast developing market,
quality assurance is crucial.

Accurate calibration of photovoltaic (PV) modules is
enormously important for R&D and production. It is an
indispensable factor for module manufacturers, investors and
operators of PV power plants. The new record value of 1.8
percent uncertainty is determined with consideration to a socalled
spectral mismatch correction. "With this value, CalLab
PV Modules at Fraunhofer ISE offers manufacturers a
reference with which they can even more precisely
determine the power output of their PV modules", explains a
visibly pleased Klaus Kiefer, Department Head, Quality
Assurance PV Modules and Power Plants. "For a production
volume of 2 GW, a power deviation of one percent
corresponds to a monetary value of about 14 million euro.
On the side of the investors, a high degree of certainty is
demanded in calculating risk premiums and in the overall
calculation for PV power plants."

The calibration laboratory of Fraunhofer ISE has been
accredited since 1986. It is considered one of the top
calibration laboratories worldwide over the past 25 years.
The researchers in Freiburg calibrate reference modules for
production lines and carry out spot checks to verify the
guaranteed power output in accordance with the
international standards. The module measurements include
the current-voltage curves as well as electrical characteristics
measured under standard test conditions (1000 W/m, 25°C
and AM1.5). For the precision measurement in accordance
with IEC 60904-1, the spectral mismatch correction is
determined according to IEC 60904-3. Here the
measurement uncertainty was improved from 2 to 1.8
percent.

In addition to highly accurate power measurements, the
researchers at Fraunhofer ISE also offer services in the
development of measurement standards for new
technologies as well as in the qualification of entire solar
simulators on production lines. Here the high-tech, accurate
measurement technology developed at Fraunhofer ISE is
used. More information about the CalLabPV of Fraunhofer
ISE can be found at: www.callab.de

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