Where does energy come from - electric polarization

[aaaa202]

Consider a dielectric between two electrodes. If you turn on power the atoms in the dielectric will be polarized, because they are in an electric field. You could also say this as the nucleus and electrons of each atom has a potential energy, which is released.
My question is: Where does this potential energy come from? Certainly it wasn't there before we turned on the voltage...?
...
Either way it must come from the creation of the field itself, where you separate + and - charge. So my next question is: Why does one not account for the extra potential needed to do this work in the equations for electrics in matter?

 

[Nate810]

The potential energy that is released when the dielectric is polarized comes from the electric field itself. As the electric field is generated, the atoms of the dielectric become polarized and acquire potential energy. This potential energy is stored in the form of electrostatic forces between the atoms and molecules of the dielectric. When the electric field is applied, the work done to create the field is not accounted for in the equations for electrics in matter. This is because the work done to create the electric field is already included in the equation. The equation takes into account the fact that work must be done to create an electric field and thus the potential energy that is released when the dielectric is polarized is included in the equation.