Connect voltage divider to Arduino

[system]

Hello,

I have a question regarding how to connect this voltage divider. In the attached image you can see the outline: I have a solar panel that generates 6V (Max) and a Voltage divior that generates 5V for 6V of solar panel, the problem is the connection to arduino is good?, it is right that black have to go to Arduino? or should only connect the orange?

[Riva]

Yes you need the black (ground) wire.

[Grumpy_Mike]

You always need a common ground to form a path for the current to flow round. See this page:-
http://www.thebox.myzen.co.uk/Tutorial/Power_Supplies.html