How to Compare two or more Power sours

I would like to know how can I Compare two or More Power sours with LM-xxx Compactor and analyse it on Arduino 328 uno Board or TI MSP430 or C2000 Board
the result should be on the LCD

Please help me to Start this Project (Power sours can be 6/12v Battery or Solar Panel’s (in a Grid) )
Thanks in advance

You can compare two voltages with a comparator but that will only tell you which of the two inputs is higher. It won't tell you the voltage. To measure the voltage you have to drop it to a safe level (below Vcc+0.5, typically 5.5V) and use an analog input to read the voltage.

Hi dear sir, thanks for your time . sir , only thats the problem I dont know how to do that . I have Arduino 328 UNO ; MSP430 Launchpad ; C2000 Launchpad Board's( I prefer Arduino) I have 16x4 LCD on which I would like to get the Reading as For Example:- if its 12v Cell or Solar Panel what's the Output each cell is giving Cell 1- 06v Cell 2- 08v Cell 3- 10v Cell 4- 126v Cell 5- 09v Cell 6- 07v ... ... Cell n- xxv

To measure each cell you need to connect the - side of the cell to Arduino Ground and the + side to an analog input. You can use a 74HC4067 analog multiplexer to select from among 16 inputs. You will need two of them: one will select the + side and one will select the - side. Wire the address pins in parallel so that you can't accidentally select the wrong combination and fry the Arduino.

The Arduino Ground MUST be isolated from the ground of the power supply you are measuring or you will fry something for sure.