Power from the PV array would be used to charge the batteries (if low) and to supply power to the “backed up” loads. (Loads that have been transferred to a new distribution panel off of the inverter) If your power usage on those circuits is low during peak sun hours, you will end up with very little power production from your PV.
I would suggest you rethink your position and type of inverter. Buying a fully integrated grid tie inverter with battery backup, so that you do NOT sell power to a “Reliable grid”, doesn’t make much sense to me.
You can build a solar system and transfer certain loads to it. Operate it as a stand alone system with grid backup. That would allow you to use all of the solar that you generate.
At the other end of the spectrum, is a grid inter tie without backup. If you do not buy a large battery bank, you could invest that money into more PV. With a larger array, you could sell more power and possibly justify the additional meter and the monthly fee. As long as you are generating the solar and making income from it, does it really matter to you, who is consuming it ?
I looked at
http://www.solarpowerrocks.com/mississippi/ They indicate that you may have a five cent spread between your purchase price and the solar selling price.