SEMI PV93 - Test Method for Accelerated Cell Level Testing for Light And Elevated Temperature Induced Degradation (LeTID) Susceptibility of Solar Cells
The purpose of the test method is to standardize the procedures, analysis and reporting for quantitatively determining light and elevated temperature induced degradation (LeTID) susceptibility of silicon solar cells.
The standard is necessary since the LeTID effect is highly sensitive to temperature and charge carrier injection of solar cells under illumination or current injection.
The test method covers the procedure for gauging silicon based photovoltaic (PV) cells with respect to LeTID with the aim of comparison/benchmarking of different solar cell concepts, production processes as well as silicon materials.
The test method defines consistent parameters for testing LeTID susceptibility of solar cells, since the LeTID effect depends on the working point of the solar cell under test, that is, if the solar cell is tested at short circuit current (Isc), open circuit voltage (Voc) or maximum power point (Pmpp).
The test method gives as a result a metric for the strength of LeTID susceptibility and for assessing LeTID mitigation procedures. It may be implemented in statistical process control routines in production on a small sample basis.
The test method is targeted at fast quantitative predictions of LeTID for solar cells later on integrated in PV modules. It is not intended for a quantitative prediction of the performance of the modules in the field.
Referenced SEMI Standards