Buy Solar Charger RAVPower 15000mAh Outdoor Portable Charger (amazon.com)

(Solar Power Bank Dual USB External Battery Pack Power Pack with Flashlight (IPX4 Splashproof, Dustproof, Solar Panel Charging, DC5V/2A Input)(Endless Charging Under the Sun: Portable battery pack charges whenever it's sunny thanks to the wide solar panel. Fast Recharging from Outlet or Solar: Dual DC 5V/2A and solar power inputs allow you to recharge no matter where you are. (DC input is recommended for faster recharging)(Under $50)(Amazon.com)