Photovoltaic Module Reliability

2Module Failure Modes

Initial product reliability assessments are based on the environment in which the product is going to be exposed, the outdoor terrestrial environment in the case of photovoltaic (PV) modules. Such an analysis can provide some clues as to the level of stresses to be encountered. The earliest module manufacturers understood that the modules would be required to endure exposure to the weather (rain, hail, and snow), high temperatures, UV, humidity, and thermal cycling. However, in most cases, the stresses were underestimated. The first generation of terrestrial PV modules was not very reliable nor did the modules survive for very long in the field. However, this first generation of product served an important function in that they failed in the field (often very quickly) allowing for subsequent analysis and development of accelerated stress tests to be described in Chapter 3. It wasn't until the product designs could be tested using the accelerated stress tests that reliability was significantly improved.

The study of PV module reliability starts with the identification of field failures. Over the years, there have been many reports of module field failures. Table 2.1 provides a list of field failures observed in crystalline‐Si PV modules. The vast majority of deployed PV modules have been crystalline silicon so this technology has the most history. The following sections will discuss the details of each of these failure modes, with emphasis on what causes ...