Charging one 48V PV system from another

[Chewie]

Hi Everyone!

I have 2 PV systems, both with 48V LiFePO4 batteries.
At the moment they are not connected.

I use a lot more power from "System 1" than "System 2".
If "System 2" is over a certain voltage (eg 54V) I would like to charge "System 1".

"System 1" is about 50m away from "System 2".
I don't think I want to just connect both batteries together as one system as the PV parts are facing in different directions, so the batteries will have different voltages at different times of the day, (and sadly are different makes).

Sterling Power do some 12 and 24v to 48v chargers:

24V to 48V Battery to Battery Charger w/ reverse charging feature + Jump Start Assistance

24V (also 12V) to 48V DC to DC Chargers 60A input and 26A output model (1600W input and 1500W output) - E-Marking | BB1248120 If you need 24V input to 48V output - please order on this page. Please note the part number for 24V input is also BB1248120 as they do both 12V input AND 24V input -...

sterling-power.com

so I guess I need something like this.

Can anyone suggest what I can do?

Thanks!

 

[TechRider]

You don't need the batteries to be the same make, as long as they're the same voltage, there should be no problem in connecting them together. During optimal times, each system will feed the the rest of the system it's power. Think of it this way, if you're drawing a load from a 2nd inverter and it would normally pull it from the battery if it's over what the PV is generating, then the first is outputting enough to charge the batteries, the 2nd inverter would use the power.

Are the 2 systems connected on the AC side at all or do they serve different AC loads as well?

 

[Chewie]

You don't need the batteries to be the same make, as long as they're the same voltage, there should be no problem in connecting them together. During optimal times, each system will feed the the rest of the system it's power. Think of it this way, if you're drawing a load from a 2nd inverter and it would normally pull it from the battery if it's over what the PV is generating, then the first is outputting enough to charge the batteries, the 2nd inverter would use the power.

Are the 2 systems connected on the AC side at all or do they serve different AC loads as well?

Thanks for the reply.

"System 1" will serve an AC load via an inverter, "System 2" mostly has low A DC loads, and a small separate inverter.

 

[TechRider]

I think we'd need a little better understanding on what you're use case is and what you're looking for.

 

[GuyG]

"System 1" is about 50m away from "System 2"

The 48-volt batteries are 50 meters apart and you want to connect them?

Step 1: Find some 750 mcm copper cable. Lots of it.

 

[TechRider]

Wow, I don't know how I missed the 50m part. That's quite a distance. If you do a double conversion, you'll end up with power loss.