*4.4. Lifetime*

As already discussed in Section 2.6, the lifetime of the converter should be comparable to the lifetime of the PV panel, which is currently in the order of 25 years with a warranted power output of 80% or more. This is, however, still not equal to the current lifetime of a façade in the order of 30 to 50 years and which is also the design target for BIPV façades.

Micro-inverter and power optimizer producers provide warranties up to 25 years for their products [64,69]. These warranties are valid for converters that are attached to the back of a BAPV module and not in the framework of a BIPV module, which is a more challenging environment.

In Reference [108], an experimental study with accelerated lifetime tests was conducted to determine the reliability issues of module-level power electronics converters. Their conclusion states that a significant number of devices failed due to the applied stress and that this is most likely a consequence of design issues rather than manufacturing issues. Keeping this information in mind, combined with more severe temperature stresses that are expected in BIPV compared to BAPV, a design-for-reliability approach for BIPV MLCs is required.
