SCT I-V Tracer

This SCT I-V Tracer measures I-V curves of solar cells both in dark as well as in a light mode. With its wide range and high accuracy of measurement as well as unique software features, the system can be an excellent tool for R & D applications in a laboratory or it may be used on a production line as the end-of-line tester/sorter of the manufactured solar cells (SC). The software has cell sorting capability. Curves are measured using common four probes (Kelvin) technique. System meets all requirements of the IEC 60904-1 standard. I-V curve of SC, either illuminated or dark, is always measured from reverse toward forward bias (from Isc to Voc) with a programmable bias step. To obtain better resolution of measurements programmable output voltage of D/A converter (the range is ±10V) controlling output voltage of the power supply biasing solar cell under test may be optionally divided by a factor of 10 resulting in output voltage range ±1.0V. Dark measurements are always performed in the auto-range mode and current range is matched to actual value of current flowing through the SC.

With SCT I-V Tracer there are two possible ways of scanning the I-V characteristics of solar cells:

• from reverse to forward direction, from short circuit current to open circuit voltage (R->F),
• from reverse to forward and back to reverse direction (R->F->R).

Main features of the I-V Curve Tracer are:

• measurement of light and dark I-V characteristics;
• short measurement time (typically < 500 ms for light measurements);
• three quadrant measurement,
• implemented advanced signal filtering procedure enabling I-V measurement even under strongly fluctuating light sources (e.g. up to ±5%);
• calculating cell series resistance according to IEC 60891 standard;
• implemented 3 procedures (IEC 60891) allowing to correct measured I-V curve to Standard Test Conditions (STC);
• wide range of measured current values (100 nA up to 20 A);
• 16 bit current and voltage measurement resolution;
• implemented numerical procedures enabling fitting of measured I-V curve to either of four equivalent diode models (SEM, DEM, VDEM, VDDEM*);
• facilities enabling fast routine determination of thermal coefficients of basic parameters of a solar cell;
• correction of measured I-V curve to any other conditions than those recorded during the test;
• advanced, easy to use measurement software (light and dark I-V curve aproximation, calculation Rectification Ratio, long term instability indicator);
• Automatic/manual solar simulator shutter control;

* VDDEM - Two Variables Double Diode Exponential Model (for dark I-V curves require finding six independent parameters, implement on request)

General Technical Specification:

Measuring Units Specification:

Below fig. shows front and rear panels of the SCT I-V Tracer.