20W USB Solar PanelThe 20W solar panels with Dual USB port, a power output of 15W (max) in the case of sufficient sunlight,it compatible with smart phones,iphones,power bank,outdoor watch GPS,security camera and etc.If 2 ports are used for charging at the same time, one side can only a power output of 10W (max).NOTE:Our solar panel can't store the electricity or power. Up to 24% High Conversion EfficiencyUSB solar charger made of 2 well-build monocrystalline silicon panels, using high transmittance ETFE material and micro-concave-convex design,which increases the contact area with the sun and the conversion rate of energy.The solar panel can convert up to 24% of the solar energy into free energy under sufficient sunlight.