The present contribution reports on the performances of ultra thin chalcopyrite Cu (In,Ga) Se (CIGS) solar cells. An alternative ZnO/CdS/CIGS/Si structure has been proposed using solar cell capacitance simulator (SCAPS). The main idea behind this analysis is the improvement of the device efficiency using materials cheaper than conventional CIGS. For that purpose, a 1 gm of a new layer p-Si has been added. Various thicknesses of CIGS absorber layer ranging from 0.1 to 1 gm have been used. Our findings showed that the increase of the absorber layer thickness leads to the improvement of the performance of the new CIGS solar cells. It was found that the best structure must have a window layer ZnO, a buffer layer (CdS), an absorbent layer (CIGS) and a Si layer with thicknesses of 0.02, 0.05, 1 and 1 gm, respectively. Cells with these features give conversion efficiency of 21.3%. The present results showed that the new ultra thin CIGS solar cells structure has performance parameters that are comparable to those of the conventional ones with reduced cost. 2017 Hydrogen Energy Publications LLC. Published by Elsevier Ltd. All rights reserved.