Advanced Characterization Methods for PV

Freiburg, Fraunhofer ISE - Thursday, January 14th 2016

Session III: Modules & Systems

3.1 M. Machado, Tecnalia (ES), “Analytical prediction of photovoltaic modules efficiency for different encapsulation schemes”

Abstract: A simple analytical calculation which allows the prediction of photovoltaic (PV) module efficiencies in different encapsulation conditions from a reduced set of experimental measurements of a reference encapsulation scheme will be presented. This procedure avoids the need to manufacture and characterize by solar simulator or External Quantum Efficiency measurements all the variety of PV modules of interest at research or manufacturing level. The absorptivity of solar cells once encapsulated is not directly accessible from direct air- bare cell or air - encapsulated cell optical measurements, and analytical or numerical methods are generally needed.  This calculation is based on an optical method for multilayer glazing systems which provides analytical expressions for the layer-by-layer absorption of the different components of a PV module. From a small set of experimental measurements and the calculated spectral absorptivity values, the short-circuit current of a module can be predicted for any encapsulation scheme. It will be proved that the method accurately matches short-circuit current density and spectral External Quantum Efficiency values of the module as obtained from experimental measurements. Results will be presented for silicon and CIGS cell technologies with several glass and encapsulation materials combinations.