Charge controller & inverter running at the same time

It is interesting to watch the meter on the charge controller as the loads change.  I've noticed that my batteries charge up pretty quickly on a sunny day, and the inverter goes to the "absorption" charging stage.  For example:  In the absorption stage the meter might indicate that charging is taking place at 20% of full capacity.  While my PV panels are capable of providing 25 amps to the load, panel current drops to 5 amps (as an example).  Then, the compressor on my refrigerator kicks in.  The load goes from 15 watts to 200 watts.  The charge controller quickly goes back to "Bulk" mode, providing as much current to the load and batteries as the PV panels are capable of producing. 

There are only a few possible scenarios, and it seems that the charge controller handles all of these in the most efficient manner possible.  The charge controller seems to power the load as the top priority.  Often, power from the panels can power the load, while still providing some power for battery charging at the same time.

On a cloudy day, with the inverter powering a load, you can watch the system go through all of the possible scenarios.  At one moment the power to the inverter load might be coming from the solar panels.  Then, a cloud passes over and the load is powered by batteries.  Often, the PV panels provide only a portion of the power needed by the load, and the rest comes from the batteries. 

I hope this answers your questions.
   

Yes, battery voltage does drop as the load increases, and that causes the charge controller to provide more current (if possible).  The charge controller seems to do what it does based on battery voltage. 

When battery charging progresses through the "absorption" stage, the % of charge (amount of charge current) gradually declines as batteries become nearer to fully-charged. 

A small increase in the size of the load will cause the % of charge to increase.  A large increase in the size of the load will cause the controller to go back into the "bulk" charge mode. 

With my system, the charge controller and the inverter do not communicate with each other.  I have, however, added automation to switch my inverter on and off based on battery voltage, but that is a topic for a whole different conversation. 

In General:  The charge controller efficiently charges the batteries, while protecting the batteries from overcharging.  My added automation protects the batteries from over-discharging.

I've explained in detail how my system works on my blog:  http://solarjohn.blogspot.com