I am building a mobile phone solar charger.

Most examples include a 1N914/1N4148 switching signal diode at the solar panel.
The purpose of the diode is to prevent the solar panel from draining power in dim light.

I'm using a YwRobot MB102 power supply module.
It has a series diode for polarity reversal protection.

Do I still need the switching signal diode?

Thank you for your help.

 

Do I still need the switching signal diode?

If I understand your description correctly; no.

 

1N914 and 1N4148 are small signal diodes.
Max forward current is 200mA.

 

Go for a 1N5817/9 series diode...