The ExpLoRer can run on a battery. By default the ExpLoRer is delivered with a coincell battery. To charge the battery you need to connect an usb and/or solar panel.
The ExpLoRer can only run on one battery at the same time, move the jumper to connect the internal (coincell) or external battery. It will only charge the battery connected with this jumper.
Connect any 3.3v – 5.2v power to the solar connector, this source will charge to battery.