A power loss model for a solar string with mixed cell types

Critical equipment in various industries depends on solar power systems to provide electrical power for remote, off grid operation. Failure of solar cells reduces power generated by a solar power system. This paper discusses solar strings consisting of mixed type of cells in terms of failure probability values, due to differences in the cell itself (such as composition, geometry, bypass diodes, interconnects, etc.) or in applied stresses from external factors. A power loss model is developed for a solar string with two different types of cells. Both types of cells are subject to failure, which can be described by two-parameter Weibull distributions. A practical example is presented to predict the expected power loss of a hypothetical solar string with 60 cells, and the results are briefly discussed.