Growatt 6KW DVM-MPV

[Quankl]

Good day,

Question. Every inverter i've seen so far has a Max Input Current from the Solar Array inside the manual. However I realise none of the non parallellable Growatts 12kw, 8kw, 6kw have this spec listed.

Seems every inverter differentiates

"Max PV Charging Current" as Charging current into the battery, whether from Solar and/or Grid Assist

and

"Max PV Input Current" - Maximum that the solar array should cap at in terms of current.

Correct me if im wrong on those two terms and if I really am missing a spec for the Growatts relating to the Array Max Current figure
Any advice?




Secondly,

Hypotherical question. Is it possible to have two different brands and capacities of batteries on multiple inverters?
For example 4 EG4 5KW Lifepo4 and then a 10KW Powerwall providing power to two of the 6KW growatt inverters which supply separate loads. There are NOT connected together at all other than the battery terminals but they also have their own Solar PV inputs feeding the same batteries.. Could that be done?

 

[BentleyJ]

Question. Every inverter i've seen so far has a Max Input Current from the Solar Array inside the manual. However I realise none of the non parallellable Growatts 12kw, 8kw, 6kw have this spec listed.

Some inverters will only list the Voc max and the MPPT max power input rating in Watts. To calculate Amps: Watts/Vmp = Amps
Vmp is the working voltage or V at max power of the array string. It's important to never exceed the Voc however, if the solar array is capable of producing more Amperage than the MPPT controller can use, the excess will be ignored. Typically over paneling of 15 to 20% is allowable.

For example 4 EG4 5KW Lifepo4 and then a 10KW Powerwall providing power to two of the 6KW growatt inverters which supply separate loads. There are NOT connected together at all other than the battery terminals but they also have their own Solar PV inputs feeding the same batteries.. Could that be done?

Its not completely clear what the question is? I assume you are not referring to a Tesla Powerwall since it has its own inverter.
I'll take a shot at answering, seems like there are actually 2 questions here.
1) It is possible to connect 2 batteries in parallel even if they have different Ah capacities. Many on the forum, including myself have a set up like that. Some have even claimed to have had success with batteries of dissimilar chemistries connected in parallel but I would not recommend it.
2) Two completely separate inverters can share a common battery as long as the charge controllers in each inverter are compatible and don't fight. If the inverters are in a stacked configuration then it's required to use a battery (or batteries) that is connected to both inverters.

 

[Quankl]

Some inverters will only list the Voc max and the MPPT max power input rating in Watts. To calculate Amps: Watts/Vmp = Amps
Vmp is the working voltage or V at max power of the array string. It's important to never exceed the Voc however, if the solar array is capable of producing more Amperage than the MPPT controller can use, the excess will be ignored. Typically over paneling of 15 to 20% is allowable.


Its not completely clear what the question is? I assume you are not referring to a Tesla Powerwall since it has its own inverter.
I'll take a shot at answering, seems like there are actually 2 questions here.
1) It is possible to connect 2 batteries in parallel even if they have different Ah capacities. Many on the forum, including myself have a set up like that. Some have even claimed to have had success with batteries of dissimilar chemistries connected in parallel but I would not recommend it.
2) Two completely separate inverters can share a common battery as long as the charge controllers in each inverter are compatible and don't fight. If the inverters are in a stacked configuration then it's required to use a battery (or batteries) that is connected to both inverters.

Ok. So the Black and White screen shot is the EG4 6KW Low Freq Specs. The Green scheme is the Growatt(6KW specifically)s.

So. If by the information you gave, the Growatt with 5000W/245V (Or 250V?) would be about 20A PV input current before the inverter starts clipping the excess.

In the EG4 Case, it seems the 27A is derived from 7500W/277V. Which seems to be the minimum range of the Max Output Power MPPT Range. Is that just coincidence or its calculated like that? If so, then the Growatt would be 5000/60V = 83Amps?

Otherwise, using the information from you would be 7500/480v( Or 500V?) giving 15A on my array into the inverter? But that seems incorrect as their specs state 27A




For 2)
Ok The key information I see in your post on this is two charge controllers are compatible an dont fight. What aspect of these Growatts make them not able to be stackable, even though im not stacking outputs (but would also mean sharing a battery bank) ?Would it be the Charge Controller section (which would means we can NOT share the battery bank and have two arrays charging via each Growatt 6KW into the same battery bank) or some other aspect? If you know.

Its not a Tesla Powerwall its a Chinese 10KW Powerwall that we have available here where I am. It comes with similar dipswitches to differentiate it. And We want to see if two Growatt Inverters 6KW DVM/MVP can be used. And it's all the same chemistry LiFePo4. Ok Just wanted to be sure. Thanks

 

[BentleyJ]

Yes to your description regarding the input volts and amps for the inverters. I believe the confusion with PV input and MPPT controllers is that there is a Range of permissible operating voltage and a range of permissible operating amps to allow for flexibility in designing the PV array. In most cases, you cannot max out both the volts and amps simultaneously without exceeding the total Watts.

I've mixed a 7.5kWh battery with a 6.1kWh battery and the current sharing between them is mostly proportioned as would be expected based on their relative sizes. Any imbalance is eliminated at both the bottom and top of the SoC range due to voltage deviations that become self correcting.

 

[Quankl]

Understoodd. Appreciated greatly.