Standards Development

Scope

This proposed test method is intended to evaluate the ultraviolet light induced power degradation (UVID) performance of unencapsulated photovoltaic cells. It focuses on standardizing UV light sources, test conditions (such as light source intensity and sample/chamber temperature), test sample, the test procedures of UVID and the method for distinguishing UVID from LID/LeTID.

The test samples could be full-size cells, half-size cells etc. Cell technologies include but are not limited to TOPCon cells, PERC cells, HJT cells, BC cells, etc.

Purpose

Research indicated that certain cell technologies, especially for N-type cells, are potentially more susceptible to UVID due to the introduction of UV-transmitting encapsulants in photovoltaic (PV) modules. The UV stability of solar cells embedded in different encapsulation polymers have been extensively studied. To improve module anti-UV performance UV down-conversion films are applied. But a cell material level standardized test method shall be defined to quantify the power degradation of photovoltaic cells after UV irradiation.

The proposed standard specifies the UVID test method for unencapsulated PV cells. Cell-level performance losses could be assessed without consideration of the interactions taking place with the other materials of the PV module. The test protocol is defined by standardizing the light sources, test sample, the test procedures of UVID and the method for distinguishing UVID from LID/LeTID.

The cell UVID focus on cell screening and aim to shorten test duration especially for new cell/process screening and reliability verification. It also enable effective mass production monitoring. Cell contributions to device degradation can be explored by distinguishing the power loss from PV cell and modules.

Additionally, this document attempts to separate the UVID from typical LID and light and elevated temperature induced degradation (LETID) by application of certain procedures.