TECHNOLOGY FOCUS - CERAMICS AND GLASS - Preferred Materials: The photoactive semiconducting material comprises tungsten trioxide (WO3) or iron (III) oxide. The second cell may comprise a dye-sensitized mesoporous titanium dioxide film in contact with an organic redox electrolyte.    TECHNOLOGY FOCUS - ELECTRICAL POWER AND ENERGY - Preferred Components: The photoactive electrode includes a film of photoactive semiconducting material (52). The second cell comprises a photovoltaic cell, e.g. a silicon photovoltaic cell (42). The photovoltaic cell is flexible. It is encapsulated between first and second conductive layers to avoid contact with the electrolyte. The first conducting layer is transparent, at least to wavelengths of light to which the photovoltaic cell is responsive. The photoactive electrode is formed as a film on the first conducting layer. The cathode (60) comprises a conductive layer formed on a side of the second conductive layer opposite to that which is in contact with the photovoltaic cell. The system includes a housing in which the device is located, an electrolyte inlet and an electrolyte outlet provided in the housing. The housing includes an outlet for hydrogen evolved at the second electrode. An indicator provides an indication when hydrogen is flowing through the outlet of the device. The device located in the housing acts as a manifold for hydrogen evolved at the second electrode to direct the hydrogen to the outlet. The circulation mechanism comprises an electrolyte reservoir coupled to the inlet by an inlet manifold and to the outlet by an outlet manifold. The inlet and outlet manifolds are coupled to the housing by self-sealing quick release connectors. An electrolyte header is located above the reservoir and in fluid communication with the reservoir. Electrolyte in the header tank serves to pressurize electrolyte in the reservoir and drive the electrolyte through the device. A hydride stack is coupled to the hydrogen output and located in close proximity to the reservoir. Heat extracted from the electrolyte serves to facilitate charging of the hydride stack with hydrogen outputted from the device. The hydride stack is coupled to a hydrogen fuel cell system operable to generate electricity from input hydrogen. A Stirling engine having a hot side and a cold side is arranged so that the hot side is in close proximity to the reservoir. The cold side of the Stirling engine is in close proximity to the fluid feed from the header tank to the reservoir. A heat exchanger is configured to draw heat from the electrolyte in the reservoir and supply that heat to a fluid supply system, e.g. domestic hot water or heating system. The electrolyte is an aqueous electrolyte. The photoactive electrode is operable to cleave water in the electrolyte to evolve oxygen.    TECHNOLOGY FOCUS - POLYMERS - Preferred Materials: The conductive layers are made of conducting epoxy.