Quantitative Moisture Mapping to Determine Local Impacts on Module Durability

Humidity is widely accepted as a risk factor to the durability of photovoltaic modules. The ingress of moisture from humid environments into the module is linked to a host of module degradation modes, including contact corrosion, encapsulant yellowing, and delamination. While these degradation pathways are studied extensively, the exact moisture content within a module is typically a hidden variable, making it difficult to establish a quantitative relationship between module moisture content and degradation. We leverage our recently developed water reflectomery detection (WaRD) technique along with biased photoluminescence imaging to spatially quantify the moisture content and cell parameters of silicon modules subjected to various damp heat conditions for 2000 hours at a 1 millimeter resolution. This unique dataset reveals two modes of series resistance increase - finger interruptions and cell-wide “background” resistance - each showing varied sensitivity to moisture exposure depending on module architecture.