Solar Panel, Vinsic 15W High Efficiency Solar Panel Foldable Portable Dual-Port Solar Charger (Black) Solar Panel High Efficiency: 15W high-efficiency solar panel provides up to 23.5%-25% conversion efficiency, while the monocrystalline panel conversion efficiency is only 15%. Intelligently Identify: Under direct sunlight, when the two USB ports are both used, the maximum current can reach to 2.1A; otherwise, when either one of the two USB ports is used, the maximum current can reach to 2.1A. It greatly improves the charging efficiency. No additional battery needed for charging external devices, 100% green energy with zero carbon footprint, built-in dual USB ports for simultaneously charging two devices. Industrial-strength PET plastic faced solar panels sewn into high-wear polyester canvas for weather-resistant outdoor durability. Perfect for rapidly charging Smartphones, Tablets, MP3 Players , GPS Units and more while emergency preparedness, Camping, Hiking , Backpacking and other Outdoor Activities.