Efficiency Estimations for Multijunction and Intermediate Band Solar Cells Using Actual Measured Solar Spectra in Japan.

An intermediate band solar cell (IBSC) whose equivalent circuit is similar to a multijunction (MJ) solar celt but with an additional parallel diode connection is shown to be more robust to spectral variation than a series-connected MJ solar cell. We have calculated the limiting efficiencies of lBSC and MJ solar cells using the measured solar spectra in Japan. Even though the maximum efficiency of an I BSC is lower than a triple junction (3J) solar cell at airmass (AM)1.5, the I BSC would generate more annual electricity by 1% than 3J cell at I sun, if they had been optimized at AMI.5. [ABSTRACT FROM AUTHOR]