A low-power photovoltaic system has been designed where energy storage is performed in two stages: a standard final one based on a battery, and an intermediary one based on supercapacitors. A prototype of the system, including a simple maximum power point tracker and a battery charger, has been realised and tested. Measurements have shown that considerable additional energy can be obtained using this approach. It will prove especially useful in climatic zones where insolation shows considerable variations within short time intervals. The circuit has been sized for a single low-power photovoltaic module which makes it suitable for investigation by students in a photovoltaics lab.