Optical constants of UV transparent EVA and the impact on the PV module output power under realistic irradiation

article
2016
authors
Vogt, M. R. and Holst, H. and Schulte-Huxel, H. and Blankemeyer, S. and Witteck, R. and Hinken, D. and Winter, M. and Min, B. and Schinke, C. and Köntges, M. and Bothe, K. and Brendel, R.
journal
Energy Procedia
doi:10.1016/j.egypro.2016.07.136

abstract

We measure and discuss the complex refractive index of conventional ethylene vinyl acetate (EVA) and an EVA with enhanced UV-transmission based on spectroscopic ellipsometry, transmission and reflection measurements over the wavelength range from 300-1200 nm. Ray tracing of entire solar cell modules using this optical data predicts a 1.3% increase in short circuit current density (Jsc) at standard test conditions for EVA with enhanced UV transmission. This is in good agreement with laboratory experiments of test modules that result in a 1.4% increase in Jsc by using a UV transparent instead of a conventional EVA. Further, ray tracing simulations with realistic irradiation conditions with respect to angular and spectral distribution reveal an even larger Jsc increase of 1.9% in the yearly average. This increase is largest in the summer months with an increase of up to 2.3%.