Hi, I found that my solar module is connected to a battery charger via USB Port , and the main components connected to the input are a 10 Kohm resistor in parallel with the bypass diode. Did any one know the role of the resistor in this design?

 

Hard to tell the exact connection of the resistor but resistors in that range are used for speed identification in USB.
https://www.beyondlogic.org/usbnutshell/usb2.shtml

A USB device must indicate its speed by pulling either the D+ or D- line high to 3.3 volts. A full speed device, pictured below will use a pull up resistor attached to D+ to specify itself as a full speed device. These pull up resistors at the device end will also be used by the host or hub to detect the presence of a device connected to its port. Without a pull up resistor, USB assumes there is nothing connected to the bus. Some devices have this resistor built into its silicon, which can be turned on and off under firmware control, others require an external resistor.