For his graduation project, TU Delft student of Sustainable Energy Technology Stefan Roest developed a new type of hybrid solar collector with a higher efficiency and a longer lifespan than the current hybrid systems. Hybrid solar collectors combine photovoltaic solar cells that convert sunlight into electricity with a solar heater that provides warm water.
A hybrid solar collector is a combination of a photovoltaic solar panel and a thermal solar collector. The residual heat from the PV solar panel is used to heat water. The water flows through a system of pipes on a copper sheet. A great deal of heat is needed to heat the water in the pipes. That is why the solar collector has been fitted with a transparent cover that helps to retain the heat. Unfortunately, the material used in the PV solar cell degrades quickly under temperatures of around 120 degrees. As a result, its efficiency is reduced by around 20 per cent and it has a lifespan of between five and ten years.
Roest developed a special solar simulator to measure the efficiency of his prototype. Almost immediately, there was commercial interest in this simulator and the relevant technology was quickly patented by TU Delft. Roest and his partner Chokri Mousaoui have since introduced the simulator onto the market via their TU Delft spin-off company Eternal Sun. Eternal Sun recently came out on top in the European finals of the BE.Project competition for students from top universities with an innovative business case, which was organised by the technology consulting company BearingPoint. The Eternal Sun team has now grown to include six students and recent graduates, and five solar simulators have already been sold since January.