Entropy production in a p-n photovoltaic converter

Abstract

The case of a non-biased (light excited) p-n photo-voltaic (PV) cell working in a closed circuit with a resistive load is investigated by means of irreversible thermodynamics in the linear range. To our knowledge, this is the first time that both electronic processes, such as photo-excitations, carrier diffusions and recombinations, and electrical processes, such as current generation and the Joule effect, are considered together in the context of thermodynamics. An equation for the built-up voltage is obtained where the recombination resistance of the diode and a collection factor of the photo-carriers, depending on the thickness of the illuminated cell-side, are included in a natural way.depending on the thickness of the illuminated cell-side, are included in a natural way. The case of a biased PV-cell is also considered concerning the empirical parallel resistance introduced in realistic models. Some insights into its real meaning have been obtained.