Analysis of a Multijunction Solar Cell Operating Under Natural Conditions
Abstract
: It is evaluated the performance of a CPV multijunction (MJ) cell (InGaP/InGaAs/Ge) of 1.0 cm2 area, for concentration rates varying from 1 up to 122X. The parameters which characterize the cell are extracted from experimental characteristic curves using the one diode model. Special attention is given to the series resistance, which affects significantly the cell performance. Results obtained show that the procedure adopted is considerably consistent, enabling to obtain a general picture of solar cell behavior in spite of large temperature and irradiance experimental variations. A large value of series resistance (3.8 ȍ) is observed for low concentration values. This resistance decays rapidly, attaining a stable value for high concentrations (0.024 ȍ). Average conversion efficiencies of 35% have been measured when converted to temperatures of 47 ºC. Series resistance obtained for high concentrations (0.024 ȍ) limit the concentration rate corresponding to maximum efficiency to values between 243 and 278. Higher efficiencies with higher concentrations, probably, require further reduction of series resistance.