Connecting several hybrid inverters to one battery - Manufacturers position

[DIYrich]

When all inverters are charging, don't exceed max charging rate of the battery. Don't exceed the max draw rate of the battery when all inverters are max drawing power.

 

[timselectric]

I missed that part. Yes, then a separate battery for each system.

Or a common battery. Which is what they want to do.

 

[GuyG]

Connecting them to the same battery shouldn't matter I agree, but better not connect them to the same ac panel..

Magic smoke !

Trying to wrap my head around how this would be (unless both inverters are off grid, or you get L1 tangled up with L2).

 

[timselectric]

Trying to wrap my head around how this would be (unless both inverters are off grid, or you get L1 tangled up with L2).

If units are connected together on the AC output. They must also be connected together with communications cables. (So that they act as one)

 

[GuyG]

What about load side AC coupling?

 

[GuyG]

ps, I’ve got a bad case of flu and am extra fuzzy-headed today. NyQuil-posting.

 

[timselectric]

What about load side AC coupling?

Load side is AC output side.

 

[zanydroid]

High voltage battery systems are definitely a different animal.
Nothing said here applies to them.

I meant high voltage MPPT and intermediate bus systems not battery. Battery still 48V

 

[timselectric]

I meant high voltage MPPT and intermediate bus systems not battery. Battery still 48V

Are you talking about over 600v?
If so, then yes. That's also on a different level.

 

[zanydroid]

Are you talking about over 600v?
If so, then yes. That's also on a different level.

No I mean 150-500V MPPT. 350VDC intermediate bus

It's the diagram that RCInFlorida posts all the time showing the power architecture of I think a Voltronic

 

[myles]

I would like to chime in here. I have concerns about two inverters using the same battery without comms.

Complete off grid.

I had a growatt 5000es hooked up to my generator charging my 48v battery( only using as charger) no AC output hooked up at all. Just Genny. Breaker. Battery bank. On the same battery I had my solark 15K hooked up powering my house loads. Reason I did this is to avoid flickering lights in the house when Genny on. Worked great UNTIL one morning I was charging with this setup and solar started producing. As soon as solar power coming into solark (again NO solar hooked up to growatt). As soon as solar soming into solark overtook the loads in house and started also charging the batteries. pOOF. Fried the growatt. Tripped my breaker. Tripped all my BMS for over current and shut everything down.

I have a thread about it you can search.

 

[timselectric]

I would like to chime in here. I have concerns about two inverters using the same battery without comms.

Complete off grid.

I had a growatt 5000es hooked up to my generator charging my 48v battery( only using as charger) no AC output hooked up at all. Just Genny. Breaker. Battery bank. On the same battery I had my solark 15K hooked up powering my house loads. Reason I did this is to avoid flickering lights in the house when Genny on. Worked great UNTIL one morning I was charging with this setup and solar started producing. As soon as solar power coming into solark (again NO solar hooked up to growatt). As soon as solar soming into solark overtook the loads in house and started also charging the batteries. pOOF. Fried the growatt. Tripped my breaker. Tripped all my BMS for over current and shut everything down.

I have a thread about it you can search.

That wasn't because two units were connected to the same battery, without communication.
It was either an internal failure in the Growatt. Or a voltage surge from the Sol-Ark, that damaged the Growatt.

 

[zanydroid]

Isn't there a presumption that the charger on the AIO is tolerant of overvoltage?

An AIO that is designed to never stack, or only natively stack, may not need overvoltage protection to satisfy the manufacturer documented use cases.

 

[myles]

That wasn't because two units were connected to the same battery, without communication.
It was either an internal failure in the Growatt. Or a voltage surge from the Sol-Ark, that damaged the Growatt.

Since the solark is still powering my house as I sit typing this. I'd say the growatt was the weak link. I have the new SRNE 10K hooked up in the same fashion now and it is a backup inverter for the whole house should we need it. But I'll only use it for charging at night in this fashion when both inverters are drawing just to be on the safe side. Those mistakes cost thousands. I'd rather buy more batteries.

 

[zanydroid]

Since the solark is still powering my house as I sit typing this. I'd say the growatt was the weak link. I have the new SRNE 10K hooked up in the same fashion now and it is a backup inverter for the whole house should we need it. But I'll only use it for charging at night in this fashion when both inverters are drawing just to be on the safe side. Those mistakes cost thousands. I'd rather buy more batteries.

I would think a chargeverter is likely designed to coexist with other chargers, like standalone MPPTs are.

 

[myles]

Isn't there a presumption that the charger on the AIO is tolerant of overvoltage?

An AIO that is designed to never stack, or only natively stack, may not need overvoltage protection to satisfy the manufacturer documented use cases.

I didn't think I was doing anything wrong with my setup. You can check my YouTube video. However I am cautious now and only charge at night to avoid any possible issue

 

[myles]

I would think a chargeverter is likely designed to coexist with other chargers, like standalone MPPTs are.

I would like to see if maybe the chargeverter has a large diode in it that doesn't allow backward flow of current into it. Only out of it. That's the solution in my mind.

 

[zanydroid]

I would like to see if maybe the chargeverter has a large diode in it that doesn't allow backward flow of current into it. Only out of it. That's the solution in my mind.

Could be like how FET based BMS police the power flow direction. It’s often with ideal diodes when the real power level kicks in.

If you look at say MeanWell chargers and power supplies output paralleling is a checkbox feature that not all of them have, and often you can only do it if there is a signaling cable between the units.

(MPPTs generally need to work without signaling cables)

 

[timselectric]

Since the solark is still powering my house as I sit typing this. I'd say the growatt was the weak link. I have the new SRNE 10K hooked up in the same fashion now and it is a backup inverter for the whole house should we need it. But I'll only use it for charging at night in this fashion when both inverters are drawing just to be on the safe side. Those mistakes cost thousands. I'd rather buy more batteries.

Since it was the Growatt that failed. It was definitely the weakest link.
But, that doesn't explain what caused it to fail.
All that I am saying is that it wasn't because they were both connected to the same battery, and not communicating with each other.
since it did happen when the Sol-Ark switched from discharging to charging. That would point to the Sol-Ark as the cause. Luckily, it only damaged the Growatt. And the BMS's were able to protect themselves.
So, I believe that you are right to be cautious moving forward.

 

[zanydroid]

I don’t think communications is guaranteed to fix it. Suppose you had some kind of universal communications hub that lets you plug two AIO into a battery at the same time. And it sort of adjusts the parameters on the fly based on what each AIO is trying to do.

If the chargers (SCC or AC) aren’t designed to work with DC coupling it might blow up.