Load the phone with the power of the sun.

The Power-Pond 7.2 watt solar charger supplied with me a HTC One (M7) with solar power.
Used until now in cycling, the 4 solar panels are mounted on a saddle bag. So the battery after a tour with track storage and music enjoyment is still almost loaded.
The module has good stable eyelets, with which you can attach it good and versatile.
Generally, the workmanship is good. One can not fault it.