Millions of Small Pressure Cycles Drive Damage in Cracked Solar Cells

In this work, we applied time-varying air pressure to a PV module containing newly cracked cells. The test used a new dynamic mechanical acceleration (DMX) apparatus. We applied pressure cycles similar to natural, wind-driven cycles. Compared with standard dynamic mechanical load (DML) tests, we applied much lower pressure (10 to 300 Pa root mean square) and many more cycles (one million at each of four pressure levels). We present a case study on a single cell in a commercial module. We monitored electrical continuity loss across cracks using electroluminescence imaging. The 10-Pa pressure cycles caused negligible change, and the 30-Pa pressure cycles caused permanent damage that continued worsening even after tens of thousands of cycles. After one million 30-Pa cycles, a series of 100-Pa cycles still caused new, permanent damage to existing cracks, and 300-Pa cycles caused further worsening and introduced new cracks.