The Solar Charging Adapter allows you to charge the Stream or Auxiliary Battery from a 30 to 50 watt solar panel with a 16-22v output. It connects to an 8mm coaxial solar connector (as used by the Goal Zero systems). Compatible with 30 to 50 watt solar panel. Requires 16-22v output from panel 8mm male coaxial solar connector Charges Stream in 1-2 hours. Comes in an IP67 waterproof hard case.