Can these inverters be used for 400V 3 phase? MPI 4K discontinued!!

RikH

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We bought a house!

Now I'm planning a big solar system. There are already 18 panels with a grid tied sma inverter. My plan is as follows:

As for now I want to let the 18 panels as they are. In addition:

3 x 15 solar panels: 275 Wp, 38,5 Voc, 31,1 Vmpp, 9,25 Asc. Ground mounted in the backyard.

3 inverters:Voltronic hybrid 4kW

But the question is can these inverters be used to take care of 1 phase each?? I cannot find anything about this in the specs. There is only stated that they can be used in parallel on 1 phase and nothing about a 3 phase config. Or should I go to the 10 kW inverter like Daromer and Wim are using?

I tried to contact Voltronic last week via there website but no answer. Two days ago I send the question to sales@voltronic.com.tw but still no reaction. Is it better to contact one of there dealers like MPP solar?

Ciao, Rik
 
If you wanted to divide the load of the house across 3x inverters you could use these.
If you want true 3 phase to eg run a 3ph motor, etc then I'd suggest looking for inverters that specifically say they can be configured for 3 phase.
If they don't specifically say they do 3 phase, then you'd have to assume they don't.
 
Redpacket said:
If you wanted to divide the load of the house across 3x inverters you could use these.
If you want true 3 phase to eg run a 3ph motor, etc then I'd suggest looking for inverters that specifically say they can be configured for 3 phase.
If they don't specifically say they do 3 phase, then you'd have to assume they don't.

Hi Redpacket, tnx for your reply. Meanwhile I found this pdf on MPP Solar website. There they are connected to 3p via energymeter and modbus. So I guess it is possible. I requested a price so hopefully they'll reply soon. Maybe it is also interesting not to take 3 x MPI 4K but the 10K 3p system. I was afraid it couldn't deleiver enough power per fase since we are planning to start cooking electrical as well but now I see it can deliver up to 16kW using a grid relay. That would be fine.

When I get more info from MPP or Voltronics I'll let it know.

Rik
 
Sounds like you need to understand your loads carefully.
If they actually need proper 3 phase that's quite different to just having a lot of kW of loads.
If you configure the inverters as 3 phase, the standby current might be different (higher) to if you had loads shared across 3x inverters if some of those loads were not used often, the inverters could switch to standby, etc.
 
Ok, Peggy from MPP replied.

This is her answer:

With MPI10kw, 3 phase, each phase will be around 3300w , divide 220vac, around 15A 15.5A each phase of ac output
But under Grid relay model. the inverter can support up to 20kw , so it will be 30A per phase .

With MPI10kw, it is currently in stock, can be sent after payment

While for MPI4kw, the lead time will be 30 days after order.
And it will be more convenient to have just one inverter to control the system instead of having 3 .

Please also find the price info here

MPI10kw : USD 2270+ USD 330 DHL fee
MPI 4kw : USD 990 /pc * 3 pc , plus DHL shipping UD 439

So it seems MPI 10kW is the way to go. I Asked here if she has some more info about how the grid relay works and how it should be connected but maybe someone here can tell that as well.
 
Grid relay is when it just relays grid over. Either combining or switching to grid power throughput.

If you look at my diagrams you can see how I wired mine. For 100% utilization you need to wire it like I do where the house is actually hooked up after the inverter. The MPI 10kW also have grid-tie function so you need approval for running that machine in most countries. Does not matter if you feed to grid or not BECAUSE its floating middle point so its impossible to 100% controll it basically. If you dont need

If you dont need to feed back to grid you are way better off using the off-grid versions. They are cheaper and less waste of energy compare to the hybrid versions.
 
Hi daromer,

Tnx for the explanation about the grid relay but what do you mean exactly. I want to connect the house as AC load on the inverter like you do. So nothing will be powered direct from the grid. But surplus of power will be feed back into the grid although I'll try to keep that to a minimum. In case there is need for more power then PV and battery can deliver it would be the best that just a little power from the grid is "mixed" just enough to power everything as is demanded. Can that be done? And if so, does this relay play a role in this process or is it simply switching the house over to grid when demand is more than rated power of inverter so ALL power is coming from the grid? But I guess thats what you mean with "Either combining or switching to grid power throughput.". So a long question in short: when will it combine and when will it put through?

About approval, yes I know. It is not that difficult here in the Netherlands.


Meanwhile Peggy answered same question:

"Grid relay is a function and it can be programmed from the inverter LCD controller
Basically, it is a feature to instruct the inverter to use Grid power ,support with the load, and it is therefore, under this feature, it can support up to 20kw of ac load power. "
 
It can combine yes. Its a nice feature but it wont do 20kw... Perhaps peak :)
 
daromer said:
It can combine yes. Its a nice feature but it wont do 20kw... Perhaps peak :)

This story continues. Received the new specs, now it says 22k for the 10kW MPI. Don't know how to attach a PDF.

I decided to go for the 4K unit but now Peggy says its out of stock. Damnit! Tried to contact Voltronic as well but they have so far never replied to inquiries via their webform nor direct email. Hmm... Any suggestions where to buy the 4K MPI?

Rik

-------------------------------------

Edit, I just called Voltronic. Talked to Steven, he promised me to answer my mails.
 
Ok, got answer from both Steven (Voltronic) and Peggy (MPPsolar), Model 4K will be discontinued. So now its plan B, the 5K model. Parallelable (is that a word?) to 3 phase / 400V AC.
 
RikH said:
Ok, got answer from both Steven (Voltronic) and Peggy (MPPsolar), Model 4K will be discontinued. So now its plan B, the 5K model. Parallelable (is that a word?) to 3 phase / 400V AC.

Are you intending that your entire house load is feed throughwhatever inverters you install ?

..... therefore you are wanting to size the inverters based on your maximum anticipated instantaneousload ?
 
Sean said:
RikH said:
Ok, got answer from both Steven (Voltronic) and Peggy (MPPsolar), Model 4K will be discontinued. So now its plan B, the 5K model. Parallelable (is that a word?) to 3 phase / 400V AC.

Are you intending that your entire house load is feed throughwhatever inverters you install ?

..... therefore you are wanting to size the inverters based on your maximum anticipated instantaneousload ?

Yes. And yes, but there isn't enough budget do do all at once. I need lots of panels since the goal is to kick out natural gas and be self-sufficient in the end. Also in wintertime.
 
RikH said:
Yes. And yes, but there isn't enough budget do do all at once. I need lots of panels since the goal is to kick out natural gas and be self-sufficient in the end. Also in wintertime.

You, along with lots of other folks have a flawed understanding of grid connected battery system topology.

In just a few words: when on grid, a battery system will operate in parallel with the grid supply, meaning it will supply an amount of energy (based on the systems rating), the remaining requirement will be sourced from the grid.

eg: a 3000va battery system and a 5000va load = battery system @ max output + 2000va from the grid.

A technically competent system will load sense at the point of utility entry (to the property) and drive the battery system such that your grid demand is kept very close to zero (while you have sufficient battery capacity)

A longer explanation can be found here -https://www.victronenergy.com/live/ess:design-installation-manual
 
Sean said:
You, along with lots of other folks have a flawed understanding of grid connected battery system topology.

Why do you think so? Is it because I don't follow the path you think is the best? I see you post that Victron link in lots of threads. Now with that out of the way I read a lot of your postings and I know they make sense. So to get back to the topic:


Sean said:
A technically competent system will load sense at the point of utility entry (to the property) and drive the battery system such that your grid demand is kept very close to zero (while you have sufficient battery capacity)

Isn't that exactly what the MPI inverter is doing? Grid goes in and load is connected on the other side so it can measure exact how much current is going in and out the grid. No need for extra CT.

Sean said:
.........when on grid, a battery system will operate in parallel with the grid supply, meaning it will supply an amount of energy (based on the systems rating), the remaining requirement will be sourced from the grid.

Agreed. The MPI inverter has a grid relay for that.

Thanks for your input Sean and now please don't think I don't appreciate it! ;)
 
MPI inverter do not have any load sensing default. It is either or.. You can hook up an SDM630 meter but how it works I dont know. I never got it to work and no help... I designed my own software to control that.

If you have the money Victron outperforms MPI/MPP gear 10x :)
 
daromer said:
If you have the money Victron outperforms MPI/MPP gear 10x :)

That is exactly my point. The money...

Anyway, after you repaired your MPI 10kW did you have any problems with it? Still satisfied? Did you find other negative sides or on the other hand very good things that are not known?

Just curious.
 
Daniel's MPI didn't need repairing, it just couldn't be made to work in the manner he wanted.

It's very often false economy to convince yourself that the cheaper product is the best option when you consider long term reliability and functionality - if you cant afford a quality system right now, save up for one.
 
Sean it did need repairing. Main mosfet board was blown after 14 months and Guarantee was 12...


Negative sides? more than it consumes way to much energy into heat? 250w idle load and around 80% efficient.
The fact that the software inside it is caotic and trying to work with its serial data is far from stable. The fact that the guarantee is 1 year and the support for it is non existent and I have had to call MPP guys multiple times because they stop answering email?
And Yes i have offered MPP help and offer to work with them or the manufacturer to sort things but they said it wasnt needed. I think it could be a good product except the people behind it doesnt care im afraid....

And yeah the positive thing? It was cheaper to buy initially....

Next time it break I will go for a better brand but yeah it will cost 2-3x the price most likely but worth it! Just the losses make up for some of that money over time :)
 
Ok Daromer, thanks for your reply. That is helpful!I'll take it into consideration. Any idea why the losses are so big?
 
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