Fast lumped series resistance measurements in solar cells

A method is presented for analyzing current-voltage (IV) measurements in both transient and steady-state condition, which can be used to determine both the ‘fast’ lumped series resistance and a hysteresis corrected IV curve. The method consists of a measurement sequence that employs two transient IV curve measurements in forward and reverse direction, accompanied by a single steady-state IV pair measured close to maximum power point. By fitting this combined dataset, the procedure determines both the fast lumped series resistance and a steady-state IV curve, with the entire measurement process completed in under 10 ms. The method's validity is confirmed through both numerical TCAD device simulations and experimental results. Values for the series resistance obtained from the proposed fast method are in good agreement with those determined using the established (slower) triple-light-level (TLL) technique. Furthermore, the maximum power derived from the hysteresis-corrected IV curve matches the value obtained from (slow) steady-state measurements within the experimental uncertainty. Therefore, the proposed measurement scheme offers a high potential for industrial application of fast IV measurements. This could enable higher throughput for IV testers providing the lumped series resistance as a quality parameter in addition to the hysteresis-corrected IV curve.