Surrey, United Kingdom [RenewableEnergyAccess.com] Hydrogen Solar, a private commercial company based at the Surrey Technology Park in the UK, announced recent success in raising investor interest and backing for their efforts toward commercializing the company’s so-called “Tandem Cell” which converts light and water directly into hydrogen fuel.The company said their latest funding round was 78 percent oversubscribed, and brought on investors beyond the UK and into the rest of Europe and the United States. The Tandem Cell consists of two photo-catalytic cells in series: the front cell absorbs the high energy ultraviolet and blue light in sunlight using nano-crystalline metal oxide thin films to generate electron-hole pairs. The longer wavelength light in the green to red region passes through the front cell and is absorbed in a Graetzel Cell, which produces electrical potential under nearly all light conditions The two cells are connected electrically and together provide the potential required to split the water molecules in the electrolyte. The Cell is fabricated from widely available and cheap materials, according to the company. Current cell efficiencies of approximately 8 percent were reported by the company. “The key to the Tandem Cell is the performance of the metal oxides in reacting to the photons of the incident light,” said the company in a statement. “We are developing processes to obtain high efficiency films in a usable form.” The metal oxides are expected to be the limiting feature of Tandem Cell efficiency, said the company, and therefore they intend to optimize all other aspects, including the counter-electrodes, the electrolytes and the mechanical design to maximize light gathering and hydrogen collection. The most expensive component of the cells is currently the specialized glass on which the nano-crystalline films are deposited, according to the company. Cheaper alternatives will be found to reduce the cost of the cell. The Tandem Cell concept was co-invented by the Swiss Federal University of Technology in Lausanne (EPFL) and the University of Geneva (UoG), and was made possible thanks to R&D support by the Swiss Federal Office of Energy over a considerable period of time. It is the subject of a patent by Prof. Michael Graetzel (EPFL) and Prof. Jan Augustynski (UoG).