The minority carrier transport length (L) is a critical parameter limiting the performance of inexpensive Cu2O-ZnO photovoltaic devices. In this work, this length is determined for electrochemically deposited Cu2O by linking the optical carrier generation profile from front and back incident-photon-to-electron conversion efficiency (IPCE) measurements to a one dimensional carrier transport model. A transport length of ~ 400 nm is estimated. This critical length explains the losses typically presented by these devices. The consequences of this L on device design with the aim of improving solar cell performance are described.