Requriements:
    os
    sys
    scipy
    numpy
    matplotlib

This Python script can be used to calculate and plot the average electrostatic potential stored in an ElecStaticPot.cube file.
Simply navigate to the directory containing ElecStaticPot.cube, and run the script using 'python path-to-tools/aveElecStatPot.py'.
The output files, ElecStaticPot_AVE and ElecStaticPot-vs-Z.png, will be generated in the same directory.
One can check the details in ElecStaticPot_AVE, where the data is already converted to eV units.