The only difference from my subsystem and the one in the image is that I wish to connect to a relay instead of just a single AC appliance, and also that one of the batteries is supposed to act as the grid. Battery A is supposed to be used to store solar power while Battery B is supposed to act as the grid for the purposes of demonstration of this project.
My questions are related to component selection. The relay is supposed to power 2 appliances; a fan and a lamp. It is also supposed to power 3 Arduinos and a Raspberry Pi.
I did some initial power calculations and I came to a conclusion that I would need a car battery to power the appliances for at least 3 hours worth of demonstration. I did not include the micro-controllers for the calculations. So the first question is: Is the power consumption from the micro-controllers big enough to need a recalculation of how much power is needed? If not, does a car battery sound reasonable for the purposes of this project?
I am trying to figure out what type of power inverter I need to fulfill my purposes. I recently found out that most grid-tied inverters switch between the backup battery and the grid when the battery is full/empty. Please correct me if I'm wrong on this. However, I have to remind you that I am planning to use a battery to represent the grid. Will a grid-tied inverter also work in this case? Also, I was hoping to be able to decide when the inverter switches back and forth between the batteries. For example, I wish to use the solar powered battery only during peak electricity rate hours. Is there a way to program an inverter to switch at only certain times?
Since I am not planning on using large solar panel cells, I am confused as to if I will need a charge controller to actually regulate the battery. The reason I am not using large solar panel cells is because I just have to demonstrate that the battery can be charged, and it does not matter how long it will take to charge it. I am just connecting a solar panel for demonstrative purposes to show the subsystem on a smaller scale than in actual implementation. Under what conditions should I use a charge controller?
Thank you for taking the time to read this. This project is being undertaken virtually unsupervised so I am trying to take advantage of any resources that I can get.