Nikkei Electronics Asia --September 2010
Green Devices
Tokyo's Solar-Powered Motor-Assisted Bicycle Stand Uses Solar Cells, Storage Batteries

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Aug 31, 2010 23:53 Tetsuo Nozawa

Using solar cells to create energy, storing it in storage batteries, and using it to drive equipment with high energy efficiency: This energy flow is one of the models for the "green society"concept, and now you can see it in actual operation in this motor-assisted bicycle stand.

Fig.1 Solar-Powered Bicycle Stand in Sakura Shinmachi, Setagaya Ward, Tokyo
This is the second solar-powered bicycle stand in the ward, following the one at Sakura Josui station on the Keio Line.
Fig.2 Solar Cells to Storage Batteries, then to Bicycles
The flow of energy from the solar cells to the storage batteries, and then to the bicycle batteries. It was clear weather when the photos were taken, but the electricity output display shows zero watt because the batteries were already at full charge.
Fig.3 Rooftop Solar Panels
A total of 36 panels are installed, each with a rated output of 210W.

A stand for motor-assisted solar-powered bicycles was opened near Sakura Shinmachi Station on the Tokyu Den-en-toshi Line in Setagaya Ward, Tokyo, in March 2010, run by the ward government (Fig.1). This is the second such solar-powered stand in the ward, following the one near Sakura Josui Station on the Keio Line. Together with the stand at Kyodo Station on the Odakyu Line, a total of 100 motor-assisted bicycles are now available as rentals to the general public at 300 yen/day.

The electricity generated by solar cells at the stands is stored to large-capacity Li-ion rechargeable batteries, then used to charge the Li-ion rechargeable batteries on the bicycles for use (Fig.2). The solar power generating systems at Sakura Shinmachi and Sakura Josui Stations both have 36 solar cells panels (rated panel output 210W), for a total of 7.56kW per station, installed on the roof (Fig.3). Li-ion rechargeable battery capacity is 9.678kWh per station, and each bicycle can run over 30km on its 160Wh onboard Li-ion rechargeable battery. "After a full charge, the system can still operate normally for two or three days even if it's raining,"says a source at Sanyo Electric Co., Ltd. of Japan. The stands are provided with back-up from the grid, ensuring normal charging operation even through periods of prolonged rain.