This study focuses on the promotion of electron transfer in microbial fuel cells (MFCs) by equipping a silicon solar cell (SSC) into the circuit. As compared to a sole MFC, a significant improvement of power output is observed in the MFC SSC, that the maximum power density increases from 7.5 W m(-3) -19W m(-3) by 2.53 times. A linear relationship between anodic potential and current has been observed when the current is below the limiting point of SSC. We estimate the electron transfer rate can be promoted in a MFC-SSC under the condition that the anodic microbial reactions are unaffected by the incorporation of a SSC. In this way, the anodic electrons are fully pumped and enter into the external circuit. This estimation is thereby demonstrated by the 24-h test, which shows the quantity of the electrons fluent in the circuit of a MFC SSC is doubled and the microbial oxidation efficiency is improved to 341.6% as compared with a sole MFC. (C) 2013 Elsevier B.V. All rights reserved.