SCT I-V Tracer

PVLogo smallThis 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).

 

Tracer View

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:

 Phase  Single Phase 
 Voltage  230 V/ 50-60 Hz (115 V on request) 
 Power consumption  ~230 VA
 Output Voltage

 ±10 V ( ±1 V subrange), 12bit resolution, higher ouput voltage possible on request

 Min. output voltage step  ~±5 mV or ~±1 mV at ±1 V subrange
 Output Current   up to ±20 A
 Storage temperature  -20 - +60°C
 Chassis  19" 4U industrial rack-mount
 Dimesions (H×W×D)  177 x 482 x 450 mm; 7” x 19” x 17.7”
 Case color  Black
 Weight  ~17 kg

 

Measuring Units Specification:

Resolution  16 bit 
Current ranges  ±20 A, ±15 A, ±10 A, ±1 A, ±100 mA, ±10 mA, ±1 mA, ±100 µA, (±20 A on request)
Voltage ranges  ±10 V, ±5 V, ±2.5 V, ±1.25 V
Software

 „Solar Cell Tester “ advanced, easy to use MS Windows environment and user friendly software

Measurement time

 depends on preset voltage/curret ranges limiting the I-V scan and step of  biasing voltage; ~2-3 sec. typically if filtering of light fluctuations is necessary (< 500 ms in case of good light stability, < ±0.5 %). Note! The overall time of  measurement usually depends also on time needed to open the shutter which is specific for the system used i applied solar simulator.

Computer Industrial class PC type at least Intel i3/i5 processor - 1 TB HDD with fast PCI DAQ (Data Acquisition Card) with 16-bit A/D and 12-bit D/A converters, 16- channel analogue multiplexer and set of binary outputs and inputs (TTL standard)

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

Tracer Front small        Tracer Rear small