An anomalous photocurrent observed in reverse‐biased SnO2‐Si heterojunctions, obtained by spraying, is reported. This current becomes voltage independent above a certain reverse voltage value and is much larger than expected from the number of photopairs generated. The anomalous photocurrent occurs above a minimum voltage value and a minimum number of incident photons, these thresholds being constant for each cell. The anomalous photocurrent is generated under the SnO2window, its density being larger under the window edge region.