Bandgaps of multi-junction solar cells potentially determined at the sun height of the culmination on the winter solstice

The optimum bandgaps varied by aerosol depth, water precipitation, latitude, and seasonal sunshine duration change as it was expected. It was also found that the optimization of the bandgaps combination at the specific site, considering ever-changing spectrum, may be determined by the matching condition to the sun height at the culmination on the winter solstice, because the distributions of optimum bandgap combinations were much closed to those of annual integration, in spite of the fact that they were calculated by a single time (single date) of the measurement. Different from AM1.5 the sun height can be taken two times a day throughout a year.