where Vcell is either the reduction potential in forming H2 or the reduction potential of
cytochrome c, depending on the mode of electron uptake, Vγ is the output potential from the photovoltaic cell, Icell is the current in the circuit, and Iγ is the current from the photovoltaic cell. This can be obtained from the current density of the photovoltaic cell Jγmultiplied by the area of the solar panel
With both \(\text{H}_{2}\)-mediated and EET-mediated electrosynthesis, we consider an upper bound on the efficiency of solar photovoltaic driven electrolysis of water and reduction to either \(\text{H}_{2}\) or MtrC, followed by oxidation of the electron source, \(\text{CO}_{2}\) fixation and fuel synthesis by an electrosynthesic organism. The photovoltaic current source is able to produce maximum power when the external potential difference \(V_{\gamma}\) is \(0.75\,\text{V}\)at a current density of \(430\,\text{A}\,\text{m}^{-2}\) \cite{Nelson:2003vl}. However, \(0.75\,\text{V}\) is too low a potential difference to split water and generate \(\text{H}_{2}\) or reduce MtrC, so needs to be transformed to a higher voltage by the transformer in the circuit (Figure \ref{270787}). The voltage required across the cell is