Entropy Production in a P-n Photovoltaic Converter

The principle of minimum rate of entropy production (MREP) is applied to a non-biased (light excited) p-n photo-voltaic (PV) cell working in a circuit closed with a resistive load. At our knowledge, this is the first time that both electronic processes, such as photo-excitations, carrier diffusions and recombi-nations, and electrical processes, such as current generation and the Joule effect are considered together in the realm of irreversible thermodynamics ruled by the MREP principle. We have found that the well known photo-cell equation is consistent with the MREP principle in the linear range. 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. 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.