Simulation of Si-based solar cell radiation resistance

In this work, we developed an I-V curve model of p-type c-Si-based solar cell (SC) with a passivated emitter at the rear contact after irradiation with 1 MeV electrons. The I–V curve is one of the key output characteristics of SCs and solar panels (SPs), from which all the main electrical parameters can be obtained and the performance of the developed design can be evaluated. Radiation is high-energy particles, which, as a rule, cause defects in the crystal lattice, increasing the internal resistance of the SCs design. The resulting defects create energy levels in the forbidden zone of the semiconductor material that act as capture (traps) or recombination centers. An increase in the concentration of traps leads to a decrease in the minority carriers’ diffusion length, which in turn reduces short-circuit current ( I sc ) and open-circuit voltage ( U oc ), significantly affecting the efficiency and power of the SC. Modeling of the degradation curves was based on the assumption that the value of minority carriers’ diffusion lengths in the base and emitter of the SC are most affected by ionizing radiation, when exposed to electrons with energy of 1 MeV in the fluence range up to 10 15 cm -2 , which is equivalent in magnitude to the radiation operating conditions of a solar panel (SP). The degradation curves of the main electrical parameters of the SC, including U oc , series ( R series ) and shunt resistances ( R shunt ), were obtained. On the basis of the calculated degradation curves of I sc and U oc , as well as the physical basis of the SCs operation, it is revealed that U oc changes more significantly, while I sc practically does not change due to the small degradation of the minority carriers’ diffusion length in the emitter. The analysis of experimentally obtained I–V curves has shown that the degradation of its maximum power point (24.8%) is affected by the decrease of R shunt and increase of R series . Approbation of the I–V curve model based on experimental irradiation of Si-based SCs by electrons with the energy of 1 MeV showed an inaccuracy of no more than 5.3%. Thus, when assessing the radiation resistance of SP, partial replacement of full-scale radiation tests of SCs by modeling will allow to speed up and reduce the cost of work.