When your phone runs out of battery, it helps to have a good external battery around for charging it. But then, eventually, you have to charge that external battery as well and your phone separately. Solar batteries can remove one plug from that equation by harnessing the power of the sun. The Poweradd Apollo does that on the cheap.
The battery pack offers up 7200mAh rechargeable by wire or the sun. If you’re going to be outdoors for awhile, on a camping trip but still need a phone, or whatever the case may be, you can keep your smartphone active and running for quite awhile. The downside is the battery only offers one USB port, so you can’t charge multiple devices at once. That said, this seems to be a common drawback with solar batteries. If you really need more ports, check out this DIY option instead.