My city is under the mud, without electricity. All people need charge a phone or a usb lantern, light and communication is very important.
Sorry for my english and sorry for my drawings, I dont have electricity, just the phone!!!!!!!
Step 1: Materials
-Converter 12 vdc to 5 vdc (2 usb port) US$6 www.aliexpress.com
-Voltage regulator 0-32 volts to 0-32 volts US$1 www.aliexpress.com
-Solar panel 10 watts (used)
Step 2: Connect
Is too easy. Connect the wires and fix the elements with glue. Is for emergency.
Step 3: Adjust
Put the solar panel at sun, the voltage in the "in" of the voltage regulator is 17 volts maybe. You need regulate the output to 12 volts.
If the "input voltaje" change (12 volts to 17 volts) the output is fixed 12 volts.
The converter change the voltage from 12 volts to 5 volts in the usb ports.