Electrothermal Finite-Element Modeling for Defect Characterization in Thin-Film Silicon Solar Modules

Abstract

Abstract-We present and validate a finite-element model for coupled charge and heat transport in monolithically interconnected thin-film solar modules. Using measured current-voltage (I-V) and lock-in thermography (LIT) measurements of amorphous silicon minimodules, we experimentally validate our model. The entire module volume is represented by two planes (front and back electrodes) which are coupled in vertical direction using 1-D models, leading to a large reduction of the degrees of freedom in the numerical model and contributing to an efficient solution approach. As compared to 3-D models, the vertical coupling of the charge transport is represented by local temperature-dependent I-V curves. These can be obtained by drift-diffusion calculations, single-cell measurements or, as presented here, by an analytical solar cell diode model. Inhomogeneous heat sources such as Joule's heating in the electrodes lead to nonuniform temperature distributions. The explicit temperature dependence in the local I-V curve, therefore, mediates the feedback of the thermal transport on the local electrical cell characteristics. We employ measured I-V curves under partial illumination and analytical solutions for the potential distribution to validate this approach. Further, with LIT measurements of the same modules with and without artificially induced electrical shunts, we verify the computed temperature distributions.

Hot spots spontaneously emerging in thin film photovoltaics

“…5) Given the device structure, thermal runaway and its related hot spots can be numerically modeled thus allowing hot spot free device engineering. Numerical algorithm developed in this work or other algorithms 17 can be used provided that they do not impose the often assumed restriction of device uniformity in the course of modeling. 6) Radiative cooling can be an important factor limiting the hot spot size and other parameters.…”

Modelling crosstalk through common semiconductor layers in AMOLED displays

“…In this section, the modelling approach is described. This model can also be applied to large‐area OLED lighting or solar cells …”

“…The entire display is at least cm 2 size (even for micro‐displays). The 2 + 1D FEM approach was previously applied to amorphous Si solar cells by Lanz . The advantage of our approach is that the number of degrees of freedom is greatly reduced compared with 3D FEM methods.…”

P.151L: Late‐News Poster: Multi‐Scale Modeling of Organic Light‐Emitting Devices

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