We've all done it: run out of battery power while out on the road. Now Sanyo has developed a device that will help road warriors get all-juiced up again.

The Japanese company has developed a solar-charging system that combines a portable solar panel with a Lithium Ion battery pack and can be used to charge gadgets via USB. It should work with many portable products including cell phones, music players and portable game devices, said Sanyo.

Two versions will be available, one with a single solar panel and one with two panels. The panels are built into a case that can be hung in a window or placed anywhere the sun is shining and are then connected to the smaller Lithium Ion battery-based "mobile booster," which acts as a reservoir and charges up from the panels. The booster is needed because the solar panels by themselves don't provide enough power to run a gadget.

A full charge of the booster will take 3 days on the single panel and half that on the twin-panel model but after just an hour it will provide enough energy to power a cell phone for 20 minutes of talk with the single panel model and double that with the twin model. It will charge faster on sunny days than overcast days. When fully charged the booster can supply 5 volts at 500mA for 2 hours, said Sanyo.

They will both go on sale in Japan on 10 August and cost ¥9,000(£56) for the single panel model and ¥14,000(£87) for the twin-panel model. Overseas launch details were not announced.