In this study, a fast-epitaxial lift-off (ELO) method was introduced and applied to transfer gallium arsenide (GaAs) single junction (SJ) solar cells to copper tungsten (CuW) substrates. In the ELO process, the time of separating solar cell epitaxial layers (epilayers) from the host substrate would influence the performance of devices. Therefore, external and internal trenches were designed to shorten the separation time. Besides, the usage of a stirrer was also used to accelerate the process. It should be noted that ELO separation time depends on chip size, rather than the size of the substrate. It only cost about 4 h to separate a 4 × 4 mm 2 chip from the host substrate in our ELO etchant. After the ELO process, the efficiency of the ELO solar cell can reach 15.81% better than 15.27% of the Ref-cell grown on GaAs substrate.