Here is a solar power bank with 20,000 mAh battery capacity that can charge your iPhone 7 times. Halo comes with a 786lm flashlight with 3 flashing modes. You can use this to power 4 devices at the same time. Halo is waterproof and dust-proof.
Halo is compatible with top iOS and Android devices. It can also work with other USB devices like GoPro and compact cameras. It weighs only 19oz. Expected to ship in November.