Application of current injection to LeTID monitoring in industrial PERC cell production

Abstract

Monitoring the light and elevated temperature induced degradation (LeTID) of crystalline silicon solar cells is becoming a standard quality control point in manufacturing. The conventional method light soaking shows several drawbacks, such as the slow response, the large footprint, and low throughput, which limit the LeTID test sampling rate, especially in GW scale mass production. Besides light soaking, LeTID can be induced by applying forward bias upon the P-N junction, which is the current injection. Here, we prove that the current injection can induce the same level of LeTID as light soaking does. In this way, a wide range of current induced degradation (CID) conditions are established on a commercialized equipment. Regarding to the multi crystalline PERC solar cells, 3.5 A-105 °C (for 157 mm cells) is chosen as an accelerated condition to induce LeTID, which is supported by simulations and experimental data.