A unique SiO2/WO3/Cu counter electrode (CE) coupled with a "2/CdS/P3HT photoanode is employed to design a cost-effective photoelectrochromic energy-conversion device for a self-powered smart window application. The main objective behind the inclusion of Cu in this device as a complement to the previously researched WO3 electrochromic counter electrode is to augment the photoelectrochromic response of the latter. The electrons made available due to hot electron injection from Cu to WO3 boost the intensity of coloration while also promoting better chromatic switching in the SiO2/WO3/Cu CE. The transmission modulation (T) under 0.25 sun at 465 nm wavelength is 50.6% for the SiO2/WO3/Cu film with a coloration efficiency of 30.6 cm2 C-1, whereas it is 39.9% for SiO2/WO3 with a much lower coloration efficiency of 22.4 cm2 C-1. The TVIS of the complete liquid photoelectrochromic assembly with SiO2/WO3/Cu CE is 41.6%, which is much higher as compared with the value of 33.6% that is obtained when the device uses only SiO2/WO3 as counter electrode. Under 1 sun irradiance, the power conversion efficiency (PCE) of the "2/CdS/P3HT-S2--SiO2/WO3/Cu cell, at 5.88%, is a noticeable enhancement over the value of 3.77% attained by using a SiO2/WO3 CE (without Cu) with the same photoanode. The high electrical conductivity of Cu allows facile charge propagation, making SiO2/WO3/Cu a proficient CE. Channelized movement of the photogenerated electrons is responsible for the vast improvement in the photoelectrochromic as well as photovoltaic performances of this novel assembly, as has been rationalized in detail in this study. © Copyright 2018 American Chemical Society.