Recent trends in the field of solar cells show that Multi-junction III-V semiconductor solar cells are an attractive option because of their high efficiency and cost effectiveness. As the first step to develop an InGaP/GaAs/Ge triple junction solar cell, we first simulated three individual InGaP, GaAs and Ge single junction solar cells using Silvaco ATLAS Software and obtained the efficiency of 13.42%, 12.99%, 3.37% for each cell respectively. Further in order to increase the efficiency of solar cell, we numerically simulated the InGaP/GaAs/Ge triple Junction solar cell by stacking InGaP, GaAs and Ge single junction solar cells and achieved high efficiency of 29.78%. The current-voltage curve, power-voltage curves and solar cell performance parameters and spectral response of each single junction solar cell as well as performance parameters and spectral response of InGaP/GaAs/Ge triple Junction solar cell have been extracted and analysed in detail. The aim of the study is to contribute to the investigation for experimental research work on the improvement of efficiency of InGaP/GaAs/Ge triple junction solar cell, through the numerical simulation, Since systematic cost of experimental investigation of the solar cell is very high and also it requires large time therefore technology computer aided design (TCAD) based simulation and performance optimization of the solar cells is important. © 2019 Elsevier Ltd. All rights reserved.