Fraunhofer Institute for Solar Energy Systems ISE
Fraunhofer Institute for Solar Energy Systems ISE
Vermessung eines Tandem-PV-Moduls im CalLab PV Modules
© Fraunhofer ISE / Foto: Bernd Schumacher

CalLab PV Modules

Calibration of photovoltaic modules

© Fraunhofer ISE / Foto: Bernd Schumacher

CalLab PV Cells / CalLab PV Modules

We measure your solar cells and PV modules with high precision, speed, and reliability.

In photovoltaics, the precise measurement of solar cells and modules is of critical importance. The Fraunhofer ISE CalLab photovoltaic calibration laboratory is one of the world’s leading laboratories offering measurement services.

We measure all types of solar cells and PV modules precisely and reliably in accordance with international standards. We have state-of-the-art equipment at our disposal for this purpose. We also develop our own specialized precision measuring instruments.

To ensure we consistently meet the highest quality standards, we regularly participate in international interlaboratory comparisons with other calibration laboratories.

 

CalLab PV Cells

CalLab PV Cells offers the calibration / measurement of solar cells from a wide range of PV technologies.

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CalLab PV Modules

Our service offer ranges from the calibration of single cells and modules to customized tasks such as the calibration of bifacial modules.

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© Fraunhofer ISE

Reference Cells

WPVS Reference Cells for primary or secondary calibration, Indoor and Outdoor Reference Cells.

CalLab Celebrates Its 40th Anniversary

Since 1986, the Fraunhofer ISE CalLab has been measuring solar cells and PV modules with the highest precision and setting new global standards. From the first calibrated solar cell to groundbreaking accreditations and the world’s first measurement of a perovskite-silicon tandem module – the lab has played a pivotal role in shaping the photovoltaic industry over four decades. Discover our most important milestones and scroll through our timeline!

  2. 1986: Founding and First Calibrated Solar Cell Measurement

    CalLab PV Cells was founded in 1986, followed five years later by CalLab PV Modules. The joint calibration laboratory measures the performance of solar cells and modules. We also ship reference solar cells and reference modules to PV manufacturers and other research institutions around the world.

    CalLab PV Cells Founding 1986
    © Fraunhofer ISE

  4. 1994: First indoor PV module measurement at ISE using a flasher

    Starting in 1991, PV modules could also be sent to CalLab to have their performance tested. Initially, this was still done in outdoor test stands under calibrated “real-world conditions.” Three years later, the CalLab team began using a device known as a “Flasher.” From then on, measurements were taken indoors in a completely darkened room using standardized flashes of light.

    CalLab PV Modules Accreditation
    © Fraunhofer ISE

  6. 1996: World’s first spectrometric characterization of a tandem solar cell

    Since 1996, CalLab has been investigating how tandem solar cells behave when spectral conditions change, as is the case throughout the day or over the course of a year. To this end, we developed a method of spectrometric characterization in which the solar cell is measured while the incident spectrum is systematically varied. This method is more relevant than ever given current research on perovskite-silicon tandem solar cells.

    Spectrometric Characterization of a Tandem Solar Cell
    © Fraunhofer ISE

  8. 2001: First measurement of a concentrator module with tandem cells, taking the solar spectrum into account

    A 192 cm² concentrator module with Fresnel lenses and GaInP/GaInAs tandem solar cells was characterized. Using the new characterization method, the module achieved an efficiency of 24.9% in outdoor tests.

    Concentrator module with tandem cells
    © Fraunhofer ISE

  10. 2006: Accreditation of CalLab PV Modules as a testing laboratory in accordance with DIN EN ISO/IEC 17025:2005

    Accreditation as a testing laboratory for PV modules was an important milestone in our development. It confirms our independence, impartiality, and technical expertise, thereby creating a reliable foundation for our work. With this accreditation, we were able to raise our quality standards to a new level and further strengthen the traceability of our testing and measurement processes.

    Flasher Measurement Technology at CalLab
    © Fraunhofer ISE

  12. 2008: Accreditation of CalLab Cells as a calibration laboratory in accordance with DIN EN ISO/IEC 17025:2005

    Calibration means understanding the measurement process so precisely that all measurement uncertainties are known, thereby enabling the measured value to be traced back to a national standard (e.g., the meter prototype). To this end, CalLab PV Cells has worked closely with the Physikalisch-Technische Bundesanstalt (PTB) since its inception, is certified according to various standards, and has been accredited as a calibration laboratory since 2008.

    CalLab PV Cells Accreditation
    © Fraunhofer ISE

  13. 2008: Substantial Expansion of Module Testing Capacity and Move to the New Module Testing Laboratory

    The move to the new module testing laboratory marked another significant step in the further development of our laboratory. The expanded facilities and enhanced technical equipment enabled us to significantly increase our testing capacity and conduct more tests simultaneously.

    New Module Testing Laboratory
    © Fraunhofer ISE

  15. 2015: Accreditation of CalLab PV Modules as a calibration laboratory in accordance with DIN EN ISO/IEC 17025:2005

    CalLab PV Modules transitions from a testing laboratory to a calibration laboratory: On March 24, 2015, the German Accreditation Body (DAkkS) confirmed CalLab PV Modules’ competence in accordance with DIN EN ISO/IEC 17025:2005 to perform calibrations in the field of photovoltaics. In doing so, the laboratory immediately sets new standards. It has become, right from the start, the first accredited laboratory worldwide with a measurement uncertainty of just 1.6%.

    CalLab PV Modules Accreditation
    © Fraunhofer ISE

  17. 2020: Reduction of measurement uncertainty for module calibration to ±1.1%

    Upon reaccreditation as an independent calibration laboratory in accordance with the new, more stringent DIN EN ISO/IEC 17025:2018 standard by the German Accreditation Body (DAkkS), CalLab PV Modules achieved a world-leading measurement uncertainty of 1.1% in the calibration of photovoltaic modules. The reproducibility of the measurements is as low as 0.2 percent. This makes the laboratory one of the world’s leading facilities. Shortly before this, CalLab PV Modules had introduced a test bench it developed in-house for the calibration of bifacial modules.

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    CalLab PV Modules Testing Laboratory
    © Fraunhofer ISE

  19. 2024: World’s First Calibrated Perovskite-Silicon Tandem Module Measurement

    We used a new multispectral solar simulator to calibrate perovskite-silicon modules. Both cell layers of the tandem module must be irradiated by different LED light sources under conditions that are as close as possible to those under which they would generate electricity in natural sunlight.

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    Perowskit-Silizium-Tandem-Modul im CalLab
    © Fraunhofer ISE / Photo: Bernd Schumacher
    The world's first calibrated perovskite-silicon tandem module measurement

  21. 2026: 40 Years of Efficiency Records

    Since 1986, the efficiencies of the cells and modules measured at CalLab have increased rapidly: As of June 2026, our accredited tests had certified world records a total of 152 times. This data is based on the Solar Cell Efficiency Tables 1 through 68 (1993 through June 2026), which have included records set by scientists at Fraunhofer ISE from the very beginning.

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    Solarzellen-Wirkungsgrade über die Jahre
    © Fraunhofer ISE