New analysis method for crystalline silicon cells

Extensive research has been done in the past in order to fit the measured IV characteristics with reliable physical models such as the two diode model. Refined mathematical methods like non linear regression analysis and additional measurement procedures like dark I-V and variable illumination Jsc-Voc have been applied in order to find reliable estimates for the parameters. We have developed a new measurement method which simplifies the basic fitting problem and does not require any additional measurement instruments or guessing the initial values for the parameters. In this method in addition to the standard IV characteristics also the decay of the open circuit voltage decay is measured when the irradiance gradually decreases to less than 100 W/m/sub 2/. Since the series resistance does not contribute to the open circuit voltage at all and the two diodes and the shunt resistance all have different voltage dependencies, it is easy to evaluate reliable estimates for these parameters. Thereafter the series resistance is the only component which is to be evaluated by fitting with the standard IV characteristics curve. We name the method irradiance decay cell analysis method (IDCAM).