M. Winkler’s scientific contributions

The Damp Heat (DH) test is an established qualification test in the PV industry. This paper presents extended DH test results of competitor modules that in part do not pass the IEC DH 1000hr test. Furthermore a large number of test samples with defined components were tested in DH. The results are analyzed and the most dominant factors for DH power degradation are extracted. Besides module components and solar cell properties that were tested in DH also the influence of the interconnection method with varied flux on the DH stability were investigated in a HAST chamber (highly accelerated test procedure). The alternative method called HAST is more closely investigated since Damp Heat is a time consuming test. The degradation for both methods is compared and it is shown that the failure mechanism is similar in both cases. The prediction of the DH-susceptibility of solar cells in the fast HAST test is the objective.

Since solar energy generation is getting more and more important worldwide PV systems and solar parks are becoming larger consisting of an increasing number of solar panels being serially interconnected. As a consequence panels are frequently exposed to high relative potentials towards ground causing High Voltage Stress (HVS). The effect of HVS on long term stability of solar panels depending on the leakage current between solar cells and ground has been first addressed by NREL in 2005. This potential degradation mechanism is not monitored by the typical PV tests listed in IEC 61215. Depending on the technology different types of Potential Induced Degradation (PID) occur. This paper is focusing on PID of wafer based standard p-type silicon technology aiming on increasing life times for solar panels once exposed to external potentials in the field. A test setup is presented for simulation of the PID in the lab and the influence of cell properties on PID is demonstrated in order to reveal the cell being the precondition for the PID. However, PID can also be stopped or minimized on panel and system level as shown in the paper.