The possibility to develop devices based on bioprocesses for solar energy harvesting is significant from the economic and environmental point of view. In this communication it has been demonstrated that such device can be can be made by controlling the equilibrium between photosynthetic and electrogenic cultures. This device is a membrane-less and mediator-free apparatus with a graphite plate anode and a stainless steel grid cathode with a steady electricity production of about 1 mV m (2). (c) 2014 Elsevier Ltd. All rights reserved.