ISFH CalTeC – Solar cells

The solar cell calibration laboratory is part of the ISFH Calibration and Test Center (ISFH CalTeC). It is accredited for the calibration of solar cells by the national accreditation body of the Federal Republic of Germany DAkkS (Deutsche Akkreditierungsstelle) under the registration number D-K-18657-01-00. The accreditation confirms that ISFHf CalTeC fulfils the ‘General requirements for the competence of testing and calibration laboratories’ of the International Organization for Standardization as defined in the ISO/IEC 17025 standard.

The scope for certified measurements of solar cells includes:

• The area (A) of the cell or the aperture mask used for the measurements.
• The spectral responsivity (SR) of the cell.
• The characteristic parameters of the current–voltage (I–V) curve (short-circuit current I_sc, open-circuit voltage V_oc, fill factor FF and power conversion efficiency η).
• The temperature coefficients α (for I_sc), β (for V_oc) and δ (for P_max).

All parameters are reported with the accompanied uncertainty following an approved measurement uncertainty analysis. In order to ensure traceability to SI units, all reference devices are calibrated at Physikalisch-Technische Bundesanstalt (PTB) – the National Metrology Institute of Germany.

The calibration service of the ISFH CalTeC focuses on the measurement of wafer-based silicon solar cells from laboratory up to industrial formats. Contacting units for typical 5 busbar solar cells are available as well as contact units for multibusbar (mBB) cells with up to 12 busbars and busbarless (BB0) solar cells. For the latter, measurements on cells with an edge length of up to 166 mm M6 can be performed.

The ISFH CalTeC is listed as a “designated test centres” to confirm solar cell efficiency records for the “Solar cell efficiency tables”. The efficiency tables published in the international journal “Progress in Photovoltaics” (Wiley) list the currently highest independently confirmed efficiencies for solar cells and modules every six months.