I am a solar power enthusiast but with almost zero knowledge in electronics. However, I have asked here and there and I managed to build a simple circuit board that should suppose to deliver me 5V in order to charge a phone through a USB port.
I read 12V from the solar panel and I can read the voltage along the red line between difference components, but once I connect the multimeter to the green terminal, I have 0V.
This is the part where knowledge kills me and I don't even know how to search for it, but shouldn't I read a voltage closer to 12V rather than 0V? Am I doing something wrong or do I need a resistance or a device that would close the system? But I was thinking that the multimeter has that inside, and that's why one can ready the voltage.
Bottom line, can anyone help me to understand why do I have 0V at the USB inlet? Is the circuit wrong?
EDIT: Here is a circuit scheme (it's the first time I built something like this, so please let me know if I need to add more info):