Change to 3 phase

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Sunnyatnight
Forum Member
Posts: 7
Joined: Sat Oct 23, 2021 6:16 am
My RE system: 3 * VFXR3048E
1 * Mate3s
1 * Hub 10
4 * fm80 - 4.5kw each
1 * fm60 - 1.6kw
8kva generator
100% off grid

Change to 3 phase

Post by Sunnyatnight »

I am fully offgrid and rely on solar PV for my business in England. I have a single 240vac generator that provides up to 8kva in an AGS setup.
I started my solar PV journey with a VFXR3048E, a Mate3s and an FM80

Storage is ~940Ah of lead acid batteries (2v*24) 48VDC
I needed more power so bought a flexpower two. I also added an FM60. This left the old VFXR as a spare
Everything works great :)

Once again I'm looking to expand and I need more power, the current ~7kw output of my two inverters will be ok for my single phase needs, what I need is to also be able to run ~11kw at 400Vac (3 phase) when needed. Maybe irrelevant but I will also be adding a four extra FM80's each with ~4.7kw of PV. I will not need to run the 3 phase items at the same time as any other single phase items.

It seems my options are:-
1) Buy another VFXR and also add my spare VFXR inverter giving me a set of 4 paralell inverters, then also buy a 3 phase converter to run my 3 phase device (a water pump). A 3 phase converter is about the same price as a VFXR3048E

2) buy a fourth VFXR like in 1 above but rewire the flexpower two into something like a flexpower four which should give 3 phase at 11kw as well as single phase like I have it today. My assumption is that this is a stack of 3 inverters but one of these has another inverter wired in parallel?
If I go this option and at a later date need more than ~7kw of single phase, will this work or can the single phase only come from the pair of inverters wired in parallel?

Which way would you go?

I am also having trouble finding a wiring and setup diagram for the flexpower four. A standard 3 phase (3 inverters) is in the manual. Any suggestions of where to get one?
raysun
Forum Emperor
Posts: 7742
Joined: Tue Jul 26, 2016 5:57 am
My RE system: Flexpower Two: (2) FXR3048A-01, (2) FM80, MATE3s, FlexNetDC
6 SimpliPhi 3.8-48 (48v @ 75AH. 450AH total)
Outback IBR3 battery enclosure
REC Alpha 440W panels - 2 arrays: each of 4 strings of 2 in series
Honda EU7000is gas fuel generator

Re: Change to 3 phase

Post by raysun »

Sunnyatnight wrote: Sat Nov 06, 2021 9:51 am I am fully offgrid and rely on solar PV for my business in England. I have a single 240vac generator that provides up to 8kva in an AGS setup.
I started my solar PV journey with a VFXR3048E, a Mate3s and an FM80

Storage is ~940Ah of lead acid batteries (2v*24) 48VDC
I needed more power so bought a flexpower two. I also added an FM60. This left the old VFXR as a spare
Everything works great :)

Once again I'm looking to expand and I need more power, the current ~7kw output of my two inverters will be ok for my single phase needs, what I need is to also be able to run ~11kw at 400Vac (3 phase) when needed. Maybe irrelevant but I will also be adding a four extra FM80's each with ~4.7kw of PV. I will not need to run the 3 phase items at the same time as any other single phase items.

It seems my options are:-
1) Buy another VFXR and also add my spare VFXR inverter giving me a set of 4 paralell inverters, then also buy a 3 phase converter to run my 3 phase device (a water pump). A 3 phase converter is about the same price as a VFXR3048E

2) buy a fourth VFXR like in 1 above but rewire the flexpower two into something like a flexpower four which should give 3 phase at 11kw as well as single phase like I have it today. My assumption is that this is a stack of 3 inverters but one of these has another inverter wired in parallel?
If I go this option and at a later date need more than ~7kw of single phase, will this work or can the single phase only come from the pair of inverters wired in parallel?

Which way would you go?

I am also having trouble finding a wiring and setup diagram for the flexpower four. A standard 3 phase (3 inverters) is in the manual. Any suggestions of where to get one?
That must be a very large water pump. Are you getting into the municipal water supply business?

I'm certainly no expert on the more esoteric inverter configurations, but have read through most of Outback's documentation on stacking. I don't recall seeing a 3-phase + 1-phase configuration. Not that it couldn't be done, but it doesn't seem to fall into the category of a mainstream design.

It would seem more "rational" to build out a system that supports the general use case, then work on adapting the special case.

It would seem a quad parallel stack of inverters producing single-phase AC with a three-phase converter for the pump would raise the fewest eyebrows should support calls be needed.
Sunnyatnight
Forum Member
Posts: 7
Joined: Sat Oct 23, 2021 6:16 am
My RE system: 3 * VFXR3048E
1 * Mate3s
1 * Hub 10
4 * fm80 - 4.5kw each
1 * fm60 - 1.6kw
8kva generator
100% off grid

Re: Change to 3 phase

Post by Sunnyatnight »

It does sometimes feel like I'm providing water for a small town! It's actually a plant nursery, the pump has to shift >100m3 of water per hour at a decent pressure.
In the end I decided to go for a standalone diesel powered pump.

The 3 phase 3+1 setup is shown at https://www.outbackpower.com/products/i ... r-four-fxr

For the 3 phase items I also needed I have gone with a rotary single to 3 phase converter.
raysun
Forum Emperor
Posts: 7742
Joined: Tue Jul 26, 2016 5:57 am
My RE system: Flexpower Two: (2) FXR3048A-01, (2) FM80, MATE3s, FlexNetDC
6 SimpliPhi 3.8-48 (48v @ 75AH. 450AH total)
Outback IBR3 battery enclosure
REC Alpha 440W panels - 2 arrays: each of 4 strings of 2 in series
Honda EU7000is gas fuel generator

Re: Change to 3 phase

Post by raysun »

Sunnyatnight wrote: Fri Apr 29, 2022 9:44 am It does sometimes feel like I'm providing water for a small town! It's actually a plant nursery, the pump has to shift >100m3 of water per hour at a decent pressure.
In the end I decided to go for a standalone diesel powered pump.

The 3 phase 3+1 setup is shown at https://www.outbackpower.com/products/i ... r-four-fxr

For the 3 phase items I also needed I have gone with a rotary single to 3 phase converter.
Hmmm... I'm seeing Series/Parallel configurations with split-phase output in the FlexPower Four docs, but not three phase + single phase. Is there a particular citation for it that I missed?
Sunnyatnight
Forum Member
Posts: 7
Joined: Sat Oct 23, 2021 6:16 am
My RE system: 3 * VFXR3048E
1 * Mate3s
1 * Hub 10
4 * fm80 - 4.5kw each
1 * fm60 - 1.6kw
8kva generator
100% off grid

Re: Change to 3 phase

Post by Sunnyatnight »

It’s quite likely my misunderstanding of the way the ‘four’ system works.
I assumed a balanced 3 phase system would have one inverter per phase. If that’s the case, what does the fourth inverter do?
raysun
Forum Emperor
Posts: 7742
Joined: Tue Jul 26, 2016 5:57 am
My RE system: Flexpower Two: (2) FXR3048A-01, (2) FM80, MATE3s, FlexNetDC
6 SimpliPhi 3.8-48 (48v @ 75AH. 450AH total)
Outback IBR3 battery enclosure
REC Alpha 440W panels - 2 arrays: each of 4 strings of 2 in series
Honda EU7000is gas fuel generator

Re: Change to 3 phase

Post by raysun »

I believe the FlexPower 3 is designed for three-phase operation (or parallel operation with 3 inverters.)

Configuring the FlexPower 4 would indeed use 3 inverters. The 4th would be a bit problematic, I'd think. Since the inverters communicate their operating mode and status the undefined role of the 4th inverter may lead to some unexpected behavior or errors.
Sunnyatnight
Forum Member
Posts: 7
Joined: Sat Oct 23, 2021 6:16 am
My RE system: 3 * VFXR3048E
1 * Mate3s
1 * Hub 10
4 * fm80 - 4.5kw each
1 * fm60 - 1.6kw
8kva generator
100% off grid

Re: Change to 3 phase

Post by Sunnyatnight »

I agree. That was the point of my original question.

Anyway, it’s a moot point now as I’ve gone a different direction.

On a different subject though. The FM80 says that the maximum wattage at 48v is 4kw. The outback string sizing tool lets me select panels up to 5kw. Do you know which is correct?
jbakker
Forum Guru
Posts: 272
Joined: Fri Feb 23, 2018 5:47 am
My RE system: 2 VFX3648 Inverters 2 FM60 150VDC Charge Controllers Mate3 5 KW of panels 15kw JC Onan NG Generator made in 1975.
1 Midnite Classic 150, FNDC. I have the Volt battery but it's not being used.
Now using 48 volt 800 AH Narada Lithium cells and QUCC 300 AMP 48 VDC relay BMS
Location: Goderich Ontario Canada

Re: Change to 3 phase

Post by jbakker »

Would not recommend going above 4kw into the FM80. Would stick with 3600 or 3800.
Cloud edge effects, the efficiency of the panels at different temperatures (colder = better efficiency) could push more than 4 kW into the FM80, will it survive this? Most likely, will it have a long and happy life? Not likely if repeatedly over-stressed. You can only punish the electronics so much and then the magic smoke will come out. Then you have to break out the wallet and buy another FM80.
Raysun has mentioned this in a post as well.
Sunnyatnight
Forum Member
Posts: 7
Joined: Sat Oct 23, 2021 6:16 am
My RE system: 3 * VFXR3048E
1 * Mate3s
1 * Hub 10
4 * fm80 - 4.5kw each
1 * fm60 - 1.6kw
8kva generator
100% off grid

Re: Change to 3 phase

Post by Sunnyatnight »

It’s a shame the sizing tool seems to show this is ok.
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