Photoelectrolysis Driven by Photovoltaics

There are several significant differences between these two systems, as follows  

The photovoltaic electrolysis cell must be covered on the illuminated side with a transparent conductor which forms an ohmic contact and is catalytic for the relevant gas evolution reaction. Metallic coatings consisting of small metal islands may also serve to stabilize the photoelectrodes against corrosion, catalyse the H2 evolution, and produce efficient photoelectrolysis. 

Conversion efficiencies for electrochemical photovoltaic cells have already been derived in Section 11.1.1.3, on the basis of the theory developed by Ross et al. [58], The maximum efficiencies were calculated on the basis of Eq. (11.12). If energy should be stored in a chemical fuel, further losses must be encountered, i.e. overpotentials, t)ox for the oxidation and rjred for the reduction, have to be considered. The latter are defined as the difference between the quasi-Fermi level and the redox potentials. Using Eq. (11.12), the conversion efficiency for the production of a chemical fuel is then given by 

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