Adding a charge controller to an existing AIO inverter?

[Rosstafarian]

I have an existing 6k solar array married to a Growatt 12k and 6 100ah trophy batteries. Everything is working great….except I’m not charging fast enough and have to lean on the grid every second or third day to top off the batteries.
I plan to add 8 panels to the system, which will put me over the 7000 watt panel limit on the inverter.
Can I put the 8 new panels on a separate charge controller that feeds the same bus bars that are currently hooked up the the batteries?
Thank you.

 

[Bobert]

I have an existing 6k solar array married to a Growatt 12k and 6 100ah trophy batteries. Everything is working great….except I’m not charging fast enough and have to lean on the grid every second or third day to top off the batteries.
I plan to add 8 panels to the system, which will put me over the 7000 watt panel limit on the inverter.
Can I put the 8 new panels on a separate charge controller that feeds the same bus bars that are currently hooked up the the batteries?
Thank you.

Should be no problem.

 

[DThames]

I have 2 Growatts and one EPEver charging one battery bank. Something you might consider is something like a Victron Smart Shunt. It will show sum of current into or out of battery. If both Growatts are charging, outputing, and the EPEver is charging the net sum of the current is going through the shunt to/from the battery. So at a glance, I can see if I am in an overall charge or discharge condition and to what degree.

 

[crossy]

Yeah, I have a Sofar AIO and a cheapo PowMr MPPT charging my packs.

They play quite nicely together until the packs are nearly full when the Sofar (which has BMS comms) stops charging before the PowMr.

 

[DThames]

Yeah, I have a Sofar AIO and a cheapo PowMr MPPT charging my packs.

They play quite nicely together until the packs are nearly full when the Sofar (which has BMS comms) stops charging before the PowMr.

Even my two Growatt, will do "last man standing". If you think about it, write the program logic for the charger output. If I want to hold float voltage, I increase the amps so that "float" is maintained, and then adjust the amps according to the voltage level. If another charger is trying to also hold float, then I back off the amps, more and more, and float is maintained all the way until I hit zero amps. it is much like turning on the cruise control of your car and then trying to maintain the set speed with the pedal. After a while, you will determine that you can let completely off the pedal and the car still is going at set speed. Dodge (for fuel economy reasons) allow the speed to drop a couple MPH on hills rather than aggressively holding speed. So on a big hill, I know I might have to give it some pedal to get more "charge" into the air-fuel mix to maintain my setting. On your dual chargers, when one doesn't keep up, the second one will start taking up the slack when needed. One thing I have noticed is my two Growatts don't report the exact same voltage at the same time. This is likely just calibration but it will affect behavior around the set points because one will sense "enough" before the other one will. It is just the normal behavior of the setup.

 

[Rosstafarian]

I have 2 Growatts and one EPEver charging one battery bank. Something you might consider is something like a Victron Smart Shunt. It will show sum of current into or out of battery. If both Growatts are charging, outputing, and the EPEver is charging the net sum of the current is going through the shunt to/from the battery. So at a glance, I can see if I am in an overall charge or discharge condition and to what degree.

So no special hardware? Just add wires from the charge controller to the bus bars for the battery bank or should I add the wire directly to the terminals on the Growatt inverter. I guess it’s the same thing? I am currently unable to fine tune my settings for the lifepo batteries because I do not know which LI setting to use in the Growatt, pending help from trophy.
Thank you

 

[DThames]

So no special hardware? Just add wires from the charge controller to the bus bars for the battery bank or should I add the wire directly to the terminals on the Growatt inverter. I guess it’s the same thing? I am currently unable to fine tune my settings for the lifepo batteries because I do not know which LI setting to use in the Growatt, pending help from trophy.
Thank you

I have some of those terminal stud bus bars. Two negative and one positive. A Smart Shunt is between the negative bus bars. All batteries go to the positive and battery side negative. All chargers/loads go to the positive and the load/charger side negative bus bars.

 

[RV10flyer]

Don't forget to install properly sized wiring and circuit protection and you should be good to go.

 

[DThames]

Don't forget to install properly sized wiring and circuit protection and you should be good to go.

I put breakers on each of my PV inputs so to easily switch them off. It is handy for me as my system is sort of a platform for testing and education. I have two chargers (24v off grid emergency and 36v golf cart) on the same array and I can power the one I want by turning that breaker on.

 

[Rosstafarian]

I have some of those terminal stud bus bars. Two negative and one positive. A Smart Shunt is between the negative bus bars. All batteries go to the positive and battery side negative. All chargers/loads go to the positive and the load/charger side negative bus bars.

Can you take a look at the diagram for me. Just want to understand where the new charge controller is added to the system. I’ve left out fuses and solar disconnect switch for sake of conversation. However, I ran 4/0 wire from batteries to buss bar (all the same length) would the wire from CC need to be the same size, I know the 4/0 was overkill.

Thank you

 

[DThames]

Yes (looking at drawing), all batteries and all charger outputs going to the same place (electrically).

 

[alvirtuoso]

I have an existing 6k solar array married to a Growatt 12k and 6 100ah trophy batteries. Everything is working great….except I’m not charging fast enough and have to lean on the grid every second or third day to top off the batteries.
I plan to add 8 panels to the system, which will put me over the 7000 watt panel limit on the inverter.
Can I put the 8 new panels on a separate charge controller that feeds the same bus bars that are currently hooked up the the batteries?
Thank you.

Where did you setup your N-G bonding?
Did you also have common neutral, that is your inverter's output neutral and grid neutral together?