[RE-wrenches] Parts List For AC Couple Disconnect

[Mark Frye]

Hi William,

Thanks, you bring up issues that are important to me here.

In particular, my situation is that the GT inverter is inter-tied a 
couple sub panels upstream of where I want to put the BB inverter. The 
distance is long, so I am looking for a solution where I don't have to 
run a cable between the two.

In general, I do wonder about using AC line voltage rise to take the Gt 
inverters off line. The main goal is to prevent excess voltage at the 
battery, so monitoring battery voltage is most direct, and there are 
simple solutions for that.

Is AC line voltage a suitable metric for achieving the same goal?

Here is where I could use Wrench knowledge to confirm my thinking, that 
being:

- With excess energy in the system, the charger moves it into the 
battery, raising it's voltage until it reaches it high charging voltage 
set point

- Once the battery reaches it's high voltage set point, the charger 
stops putting energy into the battery

- With no other place to put the excess energy, the AC voltage rises

Am I getting this right, the reason to disconnect AC coupled inverters 
when the battery if full is not to prevent the batteries from being 
overcharged, but rather to prevent the AC line from becoming unstable?

I am hoping this is correct and that with $200 of industrial grade 
devices from Digikey I can implement a robust control that will 
disconnect the GT inverters before the AC line goes so high that the BB 
inverter faults.

Mark