A USB solar panel is a portable solar-powered device designed to charge small electronic devices via USB ports. . USB ports are included in solar charge controllers for a few key reasons. What Is USB Output in Solar Charging and When Is It Enough? USB output panels are often small and. . USB solar panels have gained significant popularity among the various solar gadgets, especially for outdoor enthusiasts and those needing reliable, portable power sources. Assess the compatibility of your solar panel system with USB charging. Improvements to design and cost. .