2 inverters with 1 pv array?

[Thodoris]

Hello, everybody.
I have 2x Growatt SPF 5000 ES inverters, not connected yet.
Each inverter will give AC output to different houses. It's the same house, the ground floor has its own electrical circuit, 1st floor has its own.
So the inverters will not be paralleled.

I have 1 PV array (8x550W bifacials) and i plan to use the same PV array for both inverters.
So i will use this type of PV parallel cables. One positive input goes to each inverter's positive PV input, one negative input goes to each inverter's neg PV input.
I WILL NOT use any AC input at all.

Can i do this PV paralleling? Or will i damage the inverters? What do you think?

 

[littleharbor2]

Sorry to say you can't use one array for two separate MPPT chargers. About all you can do would be to split the array or get more panels.
BTW those MC-4 harnesses are for combining (paralleling) PV, not splitting it.

 

[Thodoris]

Sorry to say you can't use one array for two separate MPPT chargers. About all you can do would be to split the array or get more panels.
BTW those MC-4 harnesses are for combining (paralleling) PV, not splitting it.

The reason behind it is that i will cause damage to the MPPT's?

 

[littleharbor2]

The reason behind it is that i will cause damage to the MPPT's?

It could being that they are both trying to find the max power point . Splitting the array is your simplest approach.

 

[Thodoris]

It could being that they are both trying to find the max power point . Splitting the array is your simplest approach.

My original idea is that i could not think why that shouldn't work. Both inverters need an appropriate DC input voltage and both of these will receive it. The only problem would be that you cannot draw much current from both at the same time, but that's not a problem for me, as i also have a battery.

So, the idea is: Each inverter operates totally separate from the other. Why should one inverter care what the other inverter is doing as long as it has power at its input?

 

[upnorthandpersonal]

My original idea is that i could not think why that shouldn't work. Both inverters need an appropriate DC input voltage and both of these will receive it. The only problem would be that you cannot draw much current from both at the same time, but that's not a problem for me, as i also have a battery.

So, the idea is: Each inverter operates totally separate from the other. Why should one inverter care what the other inverter is doing as long as it has power at its input?

A solar panel is not a voltage source. It's a current source (in parallel with a diode, but I digress). An MPPT needs to find the maximum combination of voltage and current to provide maximum power (P = I x U --> the MPPT tries to find the optimal combination of I and U to maximize P). If you put two of them on the same array, they will fight each other.

 

[shopman]

Not only will the MPPT's fight each other but you run a good chance of shorting out the inverters due to the AC voltage that rides on some inverters PV inputs. Don't do it!

 

[Thodoris]

@shopman @upnorthandpersonal
Thanks for the replies!
So, my Plan B would be this one: Connect PV input to just Inverter #1, connect the battery bank to both inverters with appropriate bus bars.
So i can use:
Solar+Battery for Inverter #1
Only Battery for inverter #2.
Is that possible?

 

[shopman]

I cant readily think of a reason that they can't share the batteries.

 

[upnorthandpersonal]

Sharing batteries is fine.

 

[timselectric]

Plan B is the best option.
Sharing the battery bank is not a problem with these units.

 

[houseofancients]

Plan b without doubt

 

[sunshine_eggo]

Disagree.

Plan C: MOAR PANELS!!!!

 

[timselectric]

And then plan D.
Even more panels.

 

[42OhmsPA]

Once plan B, C, and D are implemented you must proceed with plan E; more Energy storage (batteriEs)

 

[teal95]

I am currently working on a system with 20 kW of panels feeding a SolArk 15k with 30 kWh of batteries. Once I have it operational I'll be adding 3x EG4 6500's to make 3 phase, pulling off the same battery bank.

Then I'll be adding more panels, wired into the EG4's, as the SolArk is already sufficiently overpanelled. Then more batteries. Then probably more panels. Eventually I'll run out of roof on the barn, so I'll have to expand the barn. ....

 

[MajicDiver]

Hello, everybody.
I have 2x Growatt SPF 5000 ES inverters, not connected yet.
Each inverter will give AC output to different houses. It's the same house, the ground floor has its own electrical circuit, 1st floor has its own.
So the inverters will not be paralleled.

I have 1 PV array (8x550W bifacials) and i plan to use the same PV array for both inverters.
So i will use this type of PV parallel cables. One positive input goes to each inverter's positive PV input, one negative input goes to each inverter's neg PV input.
I WILL NOT use any AC input at all.

Can i do this PV paralleling? Or will i damage the inverters? What do you think?

I discovered on Friday that the Growatt MIN inverters have a setting to change the behavior of the Mppt inputs. You have 3 choices 1) independent- default 2) parallel 3)DC source
No mention of this whatsoever in the “manuals”.
I suspect that if one of the 2 mppt’s connected to a single string was to be set to “dc source “ it would work just fine. I “tried” it by accident a little over a year ago and both inverters immediately tripped their output breaker. I intend to change the setting on one inverter and try it one day this week hopefully at a time when it won’t matter if we loose power.
This setting is only visible if you log into the Growatt ShineTools app with an installer account which I got on Friday after learning about it from another user on this forum.
I doubt all Growatt inverters have this setting but you might investigate.