Using an equivalent circuit model, the temperature characteristics of an InGaP/InGaAs/Ge triple-junction solar cell under concentrated light conditions were analyzed in detail. The current–voltage ( I – V ) characteristics of the single-junction solar cells (InGaP, InGaAs, and Ge solar cells) were measured at various temperatures. From the dark I – V characteristics of each single-junction solar cell, the diode parameters and temperature exponents were extracted. The extracted diode parameters and temperature exponents were applied to the equivalent circuit model for the triple-junction solar cell, and the solar-cell performance was calculated. There was good agreement between the measured and calculated I – V characteristics of the triple-junction solar cell at various temperatures under concentrated light conditions.