After Hurricane Harvey,* I ordered two RUIPU solar-powered USB auxiliary batteries [0] for about USD $40 each. Each is about the size of a very-thick iPhone 6S

After Hurricane Harvey,* I ordered two RUIPU solar-powered USB auxiliary batteries [0] for about USD $40 each. Each is about the size of a very-thick iPhone 6S Plus. One whole side consists of solar cells. The battery has three USB "power out" jacks and one micro-USB "power in" jack, allowing the battery to be charged from an electrical outlet. My two batteries now live in a window in my study, where their solar cells get several hours of direct sun every morning to keep them charged up. They seem to work OK. * We were unaffected personally, although a few nearby friends weren't as fortunate. [0] https://www.amazon.com/gp/product/B072NXV72T/ref=oh_aui_search_detailpage https://www.amazon.com/gp/product/B072NXV72T/ref=oh_aui_sear... (not an affiliate link)