10 - English Setup Connecting to AC power Before using your Bose Â® SoundLink Â® Mini speaker the first time, connect it to AC (mains) power and charge the battery. You can connect the power supply cord into the charging cradle, or directly into the speaker. While the battery is charging, you can begin using the speaker.
Ann is completely right. Given the alternative energy aspect of solar lights it seems a bit funny to have them charged by electrical lighting. Given enough direct and reflected sunlight in a room, they could be charged indoors. The stored charge wouldn't be as efficient as if they were in full sunlight though.
Since the brighter the sunlight, the more voltage the solar cells produce, the excessive voltage could damage the batteries. A charge controller is used to maintain the proper charging voltage on the batteries. As the input voltage from the solar array rises, the charge controller regulates the charge to the batteries preventing any over charging. Modern multi-stage charge controllers.