Analysis of temperature distribution in a solar element with posistor layer in the presence of local electric heat source

Abstract

The temperature distribution in a model structure in the form of a solar photovoltaic cell plate with an additional posistor layer based on a polymer matrix with nanocarbon fillers being in thermal contact is determined and investigated in the presence of overvoltages leading to the occurrence of local overheating regions. It is found that the regions of local overheating expand over time and, as a result, they spread over the entire plate of such a structure. The entire structure is heated above the phase transition temperature of the posistor layer for a time interval of the order of several seconds. The posistor layer goes into a low-conductivity state and most of the voltage drops across it. These results substantiate the prospects of using a posistor layer for electrical and thermal protection of solar photovoltaic cells from reverse overvoltages.

Modeling of temperature stabilization kinetics of solar cell with posistor layer at local overheating

“…In accordance with the concepts of [21], in the region with a reduced electrical resistance of the reverse biased p-n junction of the SC, which has an ambient temperature T0 and is in a highly conductive state, a significant current begins to flow, which can heat the indicated region and the adjacent part of the PPTC layer to temperatures equal to or higher than the temperature of its tripping to the insulating state Ttrip. As a result, the section of the PPTC layer adjacent to the region of local heating of the SC plate becomes insulating.…”

“…The solution of the first subproblem (time range t  t*) can be implemented using the heat conduction equation in a polar coordinate system and the solution algorithm given in [21], where the change in the temperature distribution profile along the longitudinal coordinate of the SC plate (r) was considered. The maximum temperature Tmax is realized directly at the point where the reverse resistance of the reverse biased p-n junction SC is minimal, i.e.…”

“…The results of a theoretical analysis of the temperature distribution in a solar cell plate without and in the presence of a posistor layer with local (point) heating of an electrical nature are presented in [20,21]. In particular, in such structure as a photovoltaic cell with an additional built-in posistor layer of the PolySwitch technology, which are in thermal contact, in the presence of overvoltages within the framework of the concept of a "spreading" heat source, it has been found that over time, the areas of local heating expand and spread onto the entire plate of the structure.…”