Developing the Science Basis for Understanding Polymer Encapsulant Degradation Mechanisms: A Scale Bridging Computational Framework

DuraMAT 2.0 Project

Multi-Scale, Multi-Physics Model

Category: Predictive Simulation

Recipient Sandia National Laboratories (PI: Wilson, Mark)

Subs Stanford University - Reinhold Dauskardt,

Status Awarded

Abstract DuraMAT researchers will perform experimental encapsulant aging studies to identify degradation products and use these results as inputs to molecular scale models to determine diffusion and reaction kinetics occurring during encapsulant degradation.

We aim to assess degradation indicators as a means to inform encapsulant material choice prior to fielding a photovoltaic module. Many factors simultaneously contribute to encapsulant degradation, however, distinguishing one specific primary driver is difficult. Concentrations of proprietary manufacturing additives, dissolved species, water, impurities, or metallization ions can result in chemical reactions that promote degradation. We refer to these collective interactions as combined effects, where encapsulant degradation occurs in the presence of one or more species with a dependence on concentration. These chemical reactions are often limited by the diffusive properties of degradation products and dissolved species, such as acetic acid and water in the case of EVA. Therefore, a more complete understanding of the heterogeneous degradation process requires knowledge of the migration of species, concentration dependence, and their combined effects on degradation rates.

In addition to developing relationships between stressor and degree of encapsulant degradation, the outcome of this work will provide material-specific properties such as activation energies for chemical reactions, rates of combined effect kinetics, and diffusional properties. These values are required input parameters for both diffusion-reaction models as well as other, higher length scale modeling efforts.