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Infinisolar 4kW Super 3 phase installation


Nicholas
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Hi all,

 

I'd like to perform an installation of 3 Infinisolar 4kW Super's at a 3 phase house. The configuration requires zero export to the grid and thus I will need to implement a smart energy meter, perhaps 3 of them.

 

I have reviewed the documentation pertaining to the "Modbus Server" which illustrates the function of the Modbus server to provide communication from a single smart energy meter (SDM630) to 3 inverters with Modbus cards. The illustration, however, pertains to the 3kW Infinisolar. My question is: Is the Modbus server compatible with the 4kW Super and will this configuration allow me to set up the system so that the inverters do not export power to the grid - i.e. Self-consumption?

modbusserver3kw.jpg

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Not to throw a spanner into the works, and also not answering your question, but when I saw "Infini 4k" I remembered there is something on the Cape Town list about this unit in 3-phase.

Quote

Note: The inverter has single-phase mains surveillance and is not able to communicate with each other to detect an out-of-bound voltage on all three phases. According to NRS 097-2-1 an external three phase mains surveillance unit is necessary for installations above 3 kW to detect an out-of-bound voltage condition on a three phase system. The inverter is intended to be used for single phase installations only.

So you will have to add a Ziehl UFR1001E device as well if you want to make it comply with NRS097-2-1.

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@Nicholas in my opinion, all dealers and installers should make their clients aware of what is happening in Cape Town right this moment.

Here is more info for your convenience. Regulations may not yet by in local municipal bylaws, but ti could be coming to a town near you in the future.

Rather the client are made aware of that upfront, mitigating potential additional costs down the line.

 

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Hi Nicholas,

this won't work.

Three InfiniSolar Super 4KW units cannot be combined into a 3-phase system. You can parallel them, but only for the purpose of creating a single-phase 12KW system. If you use the parallel communication cables and current sharing cables while feeding each unit from a different phase, it will produce an error.

What you CAN do, is to use 3x standalone unit, each being fed from a different phase and each having it's own modbus meter and modbus card. BUT, the correct angle between the phases will be maintained only when grid is ON. Once you will loose the grid, the inverters will became out of sync slowly. Therefore, it's not advisable to feed a 3-phase AirCon or a borehole pump with this setup.

For a correct 3-phase system, with battery backup, you'll need InfiniSolar 10KW 3-phase model.

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14 hours ago, Youda said:

Hi Nicholas,

this won't work.

Three InfiniSolar Super 4KW units cannot be combined into a 3-phase system. You can parallel them, but only for the purpose of creating a single-phase 12KW system. If you use the parallel communication cables and current sharing cables while feeding each unit from a different phase, it will produce an error.

What you CAN do, is to use 3x standalone unit, each being fed from a different phase and each having it's own modbus meter and modbus card. BUT, the correct angle between the phases will be maintained only when grid is ON. Once you will loose the grid, the inverters will became out of sync slowly. Therefore, it's not advisable to feed a 3-phase AirCon or a borehole pump with this setup.

For a correct 3-phase system, with battery backup, you'll need InfiniSolar 10KW 3-phase model.

Thanks, Youda, I am aware of the fact that we will not be setting them up for parallel output. The residence does not have any 3 phase equipment and we have advised the client appropriately. 

I'm still uncertain whether I can proceed as per the schematic in my original post, which illustrates the 3kW Infini in the desired configuration. 

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14 hours ago, Youda said:

Hi Nicholas,

this won't work.

Three InfiniSolar Super 4KW units cannot be combined into a 3-phase system. You can parallel them, but only for the purpose of creating a single-phase 12KW system. If you use the parallel communication cables and current sharing cables while feeding each unit from a different phase, it will produce an error.

What you CAN do, is to use 3x standalone unit, each being fed from a different phase and each having it's own modbus meter and modbus card. BUT, the correct angle between the phases will be maintained only when grid is ON. Once you will loose the grid, the inverters will became out of sync slowly. Therefore, it's not advisable to feed a 3-phase AirCon or a borehole pump with this setup.

For a correct 3-phase system, with battery backup, you'll need InfiniSolar 10KW 3-phase model.

Thanks, Youda, I am aware of the fact that we will not be setting them up for parallel output. The residence does not have any 3 phase equipment and we have advised the client appropriately. 

I'm still uncertain whether I can proceed as per the schematic in my original post, which illustrates the 3kW Infini in the desired configuration. 

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Technically, it SHOULD work, since the Intelligent Slot Cards (SNMP, modbus, wifi) are universal for the whole InifiniSolar family. Voltronic calls all these cards "goldfinger". For the card, it does not matter if the inverter is 3P or 1P. And all the cards can talk to mobus server.

But there's one potential problem with the setup - modbus card can operate in 2 modes. The first one is reseting a sum of total power in all phases to be zero. The second mode resets power in each phase individually. Therefore, you may end-up in a situation where your meter will be tracking the sum, which I bet is not what you want.

So, there will be no smoke and the setup will do "something".

 

The best doc's on the topic are on the MPPs page: https://www.mppsolar.com/v3/portfolio/energy-meter-modbus-card-modbus-server/

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15 hours ago, Youda said:

Hi Nicholas,

this won't work.

Three InfiniSolar Super 4KW units cannot be combined into a 3-phase system. You can parallel them, but only for the purpose of creating a single-phase 12KW system. If you use the parallel communication cables and current sharing cables while feeding each unit from a different phase, it will produce an error.

What you CAN do, is to use 3x standalone unit, each being fed from a different phase and each having it's own modbus meter and modbus card. BUT, the correct angle between the phases will be maintained only when grid is ON. Once you will loose the grid, the inverters will became out of sync slowly. Therefore, it's not advisable to feed a 3-phase AirCon or a borehole pump with this setup.

For a correct 3-phase system, with battery backup, you'll need InfiniSolar 10KW 3-phase model.

 

1 hour ago, Nicholas said:

Thanks, Youda, I am aware of the fact that we will not be setting them up for parallel output. The residence does not have any 3 phase equipment and we have advised the client appropriately. 

I'm still uncertain whether I can proceed as per the schematic in my original post, which illustrates the 3kW Infini in the desired configuration. 

That is still illegal.

Wether you intend to use all 3 phases or not you can't install a system that could cause a 3 phase supply to become out of phase with each other.

There are very strict rules with regards to 3 phase. People seem to think that if you don't use 3 phase outlets or equipment it is somehow ok to just pretend it is single phase.

Because the incoming breaker is 3p, any follow-up installer can reasonable install a 3p device. It isn't up to the home owner to inform the next installer that you made it 3x1p. You are not supposed to do that and the COC would be invalid and you would be legally liable should there ever be damage because of that setup. Because they can reasonable expect a single 3p breaker to signify a 3 phase installation.

There is no way this will pass inspection.

If your next thought would be to convert the 3p = 3x1p+n (or worse 3x1p) breakers then that is illegal also. 3 phase incoming must come in on a 3p or 3p+n breaker (and 1p must be broken with 1p+n)

Edited by Gnome
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Well, the truth is, that even with 3x 1P Hybrid Inverter installed, you still can use 3P loads, benefit from solar and everyhing will be in-phase. But these loads have to stay connected as depicted here:

image.png.bcf39ce008b97fde21e5e31057be6a2b.png

They will benefit from solar, but once there will be a blackout, they will stop. During blackout the inverter will be providing power to the three separate 1P outlets only. But these won't be synced with each other (as with this setup you cannot use parallel kit cables).

 

Speaking of legality - I have no clue whether it's okay or not.

 

 

 

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The only way around this is for the 3 phases in the DB (3p incoming from utility) to go to 3x1p+n breakers for each subsection and then the inverters run on those branches. It sounds silly but the incoming 3p breaker is a 3 phase installation. Anything bridging from that can use 3 phase.

Those single 1p+n breakers would also technically no longer share a neutral because each 1p+n breaker at that point has its own neutral bar running back to the main installation.

Edited by Gnome
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Reading this, I would say that safest way for Nicholas will be to buy a 3x Eastron meter and perform this as three separate 1P deployments.

Instead of going for 1x Eastron and 1x modbus server and then tuning the whole solution.

By the way, Nicholas why you are against deploying a single 3P inverter? That would simplify the setup a lot. And introduce savings on cabling and overnight self-consumption of the 3vs1 inverter....

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31 minutes ago, Youda said:

But there's one potential problem with the setup - modbus card can operate in 2 modes. The first one is reseting a sum of total power in all phases to be zero. The second mode resets power in each phase individually. Therefore, you may end-up in a situation where your meter will be tracking the sum, which I bet is not what you want.

Sometimes there are rules about how unbalanced you are allowed to make this.

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20 hours ago, Gnome said:

 

That is still illegal.

Wether you intend to use all 3 phases or not you can't install a system that could cause a 3 phase supply to become out of phase with each other.

There are very strict rules with regards to 3 phase. People seem to think that if you don't use 3 phase outlets or equipment it is somehow ok to just pretend it is single phase.

Because the incoming breaker is 3p, any follow-up installer can reasonable install a 3p device. It isn't up to the home owner to inform the next installer that you made it 3x1p. You are not supposed to do that and the COC would be invalid and you would be legally liable should there ever be damage because of that setup. Because they can reasonable expect a single 3p breaker to signify a 3 phase installation.

There is no way this will pass inspection.

If your next thought would be to convert the 3p = 3x1p+n (or worse 3x1p) breakers then that is illegal also. 3 phase incoming must come in on a 3p or 3p+n breaker (and 1p must be broken with 1p+n)

I disagree. 

The only requirement for a 3-phase supply to remain synchronised and in-phase is to supply a 3-phase load. My proposed installation/configuration can indeed accommodate a 3-phase load/machine - it would simply need to be upstream of the inverter, i.e. on the grid-tied side of the inverter connections. This means that the 3 phase load will benefit from the PV generation of the 3 inverters, but will not be backed up in the event of a power outage, i.e. the 3-phase load will not be on the output (Backup) side of the inverter. 

With regards to your statement about follow-up installers installing a 3-phase device - I disagree: it is the homeowner's responsibility to inform the technician that there is on-site electricity generation and an alternative power supply to the Utility. This message should be reinforced by appropriate signage on all distribution boards indicating as such. I will not respond to each of your statements thereafter suggesting the illegality of the proposed configuration because I suspect that you are unfamiliar with the wiring of an Infinisolar inverter. Nonetheless, I will clarify that the output of each inverter will be supplied through a single phase live and neutral breaker (The input and output neutrals will be separate). 

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20 hours ago, Youda said:

But there's one potential problem with the setup - modbus card can operate in 2 modes. The first one is reseting a sum of total power in all phases to be zero. The second mode resets power in each phase individually. Therefore, you may end-up in a situation where your meter will be tracking the sum, which I bet is not what you want.

The best doc's on the topic are on the MPPs page: https://www.mppsolar.com/v3/portfolio/energy-meter-modbus-card-modbus-server/

 

That is a very good point. I just reviewed the document: Modbus card user manual and the setup is indicated for the "3-inverter" configuration. 

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20 hours ago, Youda said:

Reading this, I would say that safest way for Nicholas will be to buy a 3x Eastron meter and perform this as three separate 1P deployments.

Instead of going for 1x Eastron and 1x modbus server and then tuning the whole solution.

By the way, Nicholas why you are against deploying a single 3P inverter? That would simplify the setup a lot. And introduce savings on cabling and overnight self-consumption of the 3vs1 inverter....

So far, there is little doubt that I have that the 4kW Super is significantly different to the 3kW Plus, which is suggested by Voltronic to operate successfully in the illustration presented in my original post. Instaling 3 Eastron SDM630's is going to be quite an inelegant solution, including significant extra cost. 

The reason we are looking to implement 3 single phase hybrids as opposed to a single 3 phase hybrid is for several reasons:

  1. We need 3 MPPT's because of the unique roof construction at the installation site. (Infinisolar 10kW only has 2)
  2. We need a little more output than the 3.3kW per phase provided by the Infinisolar 10kW
  3. We suspect that PV utilisation is better when incorporating single-phase inverters, one per phase, as opposed to a 3-phase inverter. I shall elaborate below:

I stand to be corrected, but it is our understanding that a 3-phase grid-tied inverter produces the same output over each phase. So if said inverter was supplying 3kW, each phase would be receiving 1kW. In order to do this, the inverter would need to identify the lowest load across all 3 phases and supply that amount of load per phase. This implies that if the load is not well balanced, then the potential PV supply capacity is scuppered. Experience has shown us how dynamic and unbalanced loads in a residence can be, and with that in mind, the performance improvements offered by the 3 inverter configuration is certainly worth the consideration.

 

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6 minutes ago, Youda said:

... if you need 3 MPPT inputs ...

How about getting say 3 Victron MPPT controllers, on the same battery bank, with just 1 large inverter?

Having 3 identical controllers on the same bank, all set to the exact same setting, can work.

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29 minutes ago, The Terrible Triplett said:

Having 3 identical controllers on the same bank, all set to the exact same setting, can work.

There is a new network feature where they can synchronise (without a CCGX or Multi), so they act like a single charger. Can be combined with the new Smart Battery Monitor, a Bluetooth thing. If you want to go that way...

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9 hours ago, Youda said:

Hi Nicholas,

FYI, Infini10K is one of the few "assymetric" inverters on the market. It can generate a different amount of power in each phase.

 

Thank you, that is very helpful to know. The value proposition of the Voltronic Infinisolar range continues to astound me.

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9 hours ago, The Terrible Triplett said:

How about getting say 3 Victron MPPT controllers, on the same battery bank, with just 1 large inverter?

Having 3 identical controllers on the same bank, all set to the exact same setting, can work.

I'd love to consider this, but I'm just too unfamiliar with the Voltronic Victron (moderator edit) product line. I think the quality of their equipment and the engineering development therein is unparalleled, but the price point and extensive documentation and subsequent knowledge required to become adept with the solutions offered, has unfortunately steered us towards the Voltronic Power range. This is no excuse and I do plan to become more familiar with the product line and understand its value proposition.

In this case, I'm concerned about how the entire solution would integrate without sacrificing the Infinisolar inverter too and moving over to a Multi/Quattro + Colour Control to be integrated with the MPPT charge controllers...

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Truth be told, sometimes I feel like that Dutch Reformed dominee who explained infant baptism to the baptist pastor... and then afterwards said to that same pastor... please don't break your tradition. It is important too!

I'm not sure shoving a blue charge controller in everywhere is always the answer :-)

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Came across this image (2nd below) on the Voltaconsolar website with regards to the Modbus server. This seems to suggest that the 4kW Infini would be supported. Does anybody know what the board in the 1st picture is? The "Modbus server" seems to indicate an RS232 port and not an RS485 port. Perhaps the little board is an RS232 to RS485 converter?

Voltacon_modbus_server_bundle.png

Voltason_4kW_implied.png

Edited by Nicholas
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On 2018/07/28 at 10:25 AM, plonkster said:

Truth be told, sometimes I feel like that Dutch Reformed dominee who explained infant baptism to the baptist pastor... and then afterwards said to that same pastor... please don't break your tradition. It is important too!

Plonkster and the Dominee must decided on a tradition and stick to it, come hell or blue water. :P

 

On 2018/07/28 at 10:25 AM, plonkster said:

I'm not sure shoving a blue charge controller in everywhere is always the answer :-)

True, it is not, however sometimes taking a firm stance on a decided "tradition" can help a lot more than flopping around out of the blue water. :D

(I just had too!)

 

On 2018/07/28 at 8:59 AM, Nicholas said:

... the price point and extensive documentation and subsequent knowledge required to become adept with the solutions offered, has unfortunately steered us towards the Voltronic Power range.

Price yes, the rest no. The supplier of the equipment is there for your assistance, and if they cannot help, then one can go to SA regional assistance, or another supplier. And if that does not solve the problem, one can go direct to the manufacturer. Everyone is ready to help. They can even help remotely, for free, T&C's apply, obviously.

Any case, if was just an idea, as I don't have the same view as the Dominee nor Plonkster, being firmly on the one side, the other side just being wrong! (read 'I threw a rock in the bush').

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6 hours ago, Nicholas said:

Does anybody know what the board in the 1st picture is? The "Modbus server" seems to indicate an RS232 port and not an RS485 port. Perhaps the little board is an RS232 to RS485 converter?

The board looks exactly like a [ edit: 2014 ] RS232 board for an Axpert, e.g. see many versions of it here: http://forums.aeva.asn.au/viewtopic.php?p=57957#p57957 . My guess is that this would go inside your Infini. Do you have a place where this can go? The grey box seems to need to send RS232 commands to the inverter. I don't know why they have WatchPower software pictured. That's the monitoring software provided with Axperts; hybrids use SolarPower. So maybe the image isn't accurate; this may be the photo from a similar product for off-grid inverters. Caution is advised.

Edited by Coulomb
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I agree, I think the image may have been mistakenly put there for the Infinisolar Hybrids. I've bought a Modbus server and it does not come with that extra board and it says RS485 on the one RJ45 port and not RS232.

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