Low-ion front glass

Low-ion front glass means building the module with a front glass that has a lower ion concentration. It is a module-level way to prevent Potential Induced Degradation (PID). It targets PID shunting. In this mode, a high voltage between the cells and the grounded frame drives leakage currents that move sodium ions out of the glass toward the cells. Standard soda-lime front glass contains sodium and speeds up PID. Its sodium ions travel to the anti-reflective layer, collect there and enter defects in the cell junction, where they form shunts. When judging a front cover for PID risk, the relevant properties are its electrical conductivity, sodium ion concentration, ion mobility and leakage current. This is a choice made in module design or purchasing. It can be combined with other module-level measures, such as an alternative encapsulant like TPO. It has limits. Sodium can also come from the rear glass and through the encapsulant. PID also depends on string voltage, polarity, grounding, heat, humidity, wetting and soiling. Changing the glass does not address PID polarization, a separate mechanism caused by surface charge building up on the cells. Choosing modules sold as PID-resistant is the broader option.

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• sentence 2: support check: partial - Passages describe PID-s with high voltage, leakage currents and Na+ migration from glass to cells, but don't say a low-ion glass targets PID-s explicitly, and 'grounded frame' and 'move out of the glass' are loosely stated.
• sentence 5: support check: partial - TPO encapsulant alternative is listed alongside low-ion glass as module-level measures, but the passages don't state it's a design/purchasing choice or explicitly that they can be combined.
• sentence 7: support check: partial - PID-p is caused by surface charge buildup and PID-resistant modules exist, but the passages don't say glass change fails to address PID-p or that PID-resistant modules are the broader option. -->