I took my 14 Watt Anker solar charger to the beach and made good use of it charging phones, tablets and portable speakers.
In this video you can see an iPhone 4 charging at around 1amp, consuming roughly 5 watts.
The Anker portable usb solar charger has 2 ports for charging multiple devices. You could also connect a USB hub and charge additional devices but they’d charge slower since power would be distributed among them all.
The little black box that shows the voltage, current and power is the portapow usb power meter.