We present a novel method to remove the unwanted covellite (CuS) in Cu-rich prepared CuInS2-CdS-ZnO photovoltaic cells by a combined chemical/electrochemical procedure. Our treatment results in a solid-state transformation by electrochemical reduction in an alkaline electrolyte with subsequent chemical dissolution. The reduction is carried out at -0.95 V vs. saturated calomel electrode. The chemical and electrochemical reactions leading to the dissolution are discussed. After completion of the treatment a pronounced photoeffect is observed. X-ray diffraction shows complete removal of CuS. Scanning electron microscopy confirms a distinct change in morphology.