Autotransformer Question

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Bryant
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Autotransformer Question

Post by Bryant »

I have purchased all my equipment, and will be installing soon. Plan to stack two VFX3524 inverters (Outback Stacking) I have read, and understand the use of FW-X240 to balance the inverter loads. Might sound like a silly question and perhaps I'm missing something, but the two inverters will combine to supply a max of 7,000 watts, however the autotransformer is rated up to 4Kva. Will I not be able to use all available power without overloading?

I only have one appliance that requires a 240v load (a mini split AC). Is it still best I stack the inverters series-parallel with the autotransforer, or just stack them parallel and use the autotransformer to provide the 180deg out of phase leg just to power the minisplit?

Lots to learn as I read, and sometimes a bit overwhelming.

Thanks
Bryant Davis
ralphday224
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Re: Autotransformer Question

Post by ralphday224 »

Hi Bryant
I have a single Outback 3648 inverter. I run a Mitsubishi heat pump (12,000 btu) off a dedicated circuit (house panel) running a t240 autotransformer. works just fine. I have the autoformer on a plug. I can 120v from the house system or the utility. Cooling uses much less power than heating, so usually cool on the house re system.

The transformer has a breaker to turn on or off for 240v. A double pole switch in a box on top and a little neon/led light on the transformer box so I know when it's powered...it hums too. The standby load of the autotransformer is :

50voltamps just tx
53voltamps tx and Mits "on"

9watts just tx
30watts tx and Mits "on"

Must have something to do with power factor the 9 watts vs 50va readings difference.

Do you really need all that inverter capacity? Could you run the autotransformer just off one inverter?

Ralph
raysun
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Posts: 9378
Joined: Tue Jul 26, 2016 5:57 am
My RE system: Flexpower Two: (2) FXR3048A-01 - Series Stacked, (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
2 Midnite Solar MNPV6 combiners w/20A DC disconnects.
Honda EU7000is gas fuel generator
Off-Grid

Re: Autotransformer Question

Post by raysun »

Welcome to the forum, and the world of producing your own power!
As you've experienced, there's lots to learn, and that never stops. To help us help you get the most out of your system, take a few minutes to read and follow the suggestions here: viewtopic.php?t=17533
Last edited by raysun on Sun Jan 22, 2023 2:57 pm, edited 1 time in total.
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Mike Curran
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Posts: 2966
Joined: Sat Aug 28, 2004 6:28 pm
My RE system: Outback - Garage roof (2007/2017):
- 8 (2x4) Evergreen 180's into one FM80 (2007/2020 - replaced MX60)
- 6 (2×3) ALEO S79-300's into one FM80 (2017)
- 2 grid-tied VFXR3524A-01's series stacked, replaced GVFX's (2020)
- 12 Surrette/Rolls 2V x 1766Ah (2007)
- Hub10.3, Mate3s, FNDC, RTS. Tigo ES maximizers on each PV module.

Westinghouse Solar - Barn roof: (2012)
- 30 (2x15) 235W panels with Enphase M215 microinverters, grid-tied

Outback Skybox - Barn roof: (2019)
- 14 Talesun 275W in series (DC array input to SB inverter/charger)
- 3 SimpliPhi 3.8 batteries, 48V, 225Ah total
- AC coupled input from 14 Talesun 275W, Enphase M215 microinverters

Battery systems operate in grid-tied, net metering w/backup mode
All self-designed and self-installed
Location: Chagrin Falls, Ohio

Re: Autotransformer Question

Post by Mike Curran »

I'm grid-tied and my system is strictly for battery backup. My 2 VFXRs are series stacked to provide power to my sole 240VAC load, my well pump, similar to your mini-split situation. I wired the 120VAC loads on my backup loads panel split between the 2 inverters so that each inverter would have roughly equal 120V loads to handle in the event of a grid outage. If you have multiple 120V loads you might want to consider not using the X240 - may not be necessary - and wiring like mine. Just a thought.
https://ei.tigoenergy.com/p/pZXn7SZQyO45
https://enlighten.enphaseenergy.com/public/systems/Hctc107221
Bryant
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Re: Autotransformer Question

Post by Bryant »

I greatly appreciate the responses.

Raysun- I read the link you provided, but not sure how precharge resistors relate to my question?

I'm still wondering if by using a autotransformer to balance the loads, if my system will be limited by the capacity of the autotransformer. Outback manual states that autotransformer is required when stacking series/parallel, but seems counterproductive of the purpose of stacking if wattage is limited.

My next question is in regards to my array. I understand wiring the panels in series, parallel, etc. to achieve different configurations. It is my understanding that no matter how they are wired, the wattage is the wattage. Example..On the flexmate 80, the datasheet indicates a max array size of 1,500 watts on a 24v system. I have 260 watt panels, which means that no matter how they are wired, I can only use a max of 6 panels (260 X 6=1,560...actually a little over, but panels are never likely to be at 100% efficiency). Am I understanding this correctly?


Also- Figure I will list my equipment, although not installed quite yet.
I have an off-grid cabin on the Texas coast.

I have:
2 - VFX3524 Inverters
1 - Flexmate 60
1 - Flexmate 80
1 Hub
1 Mate
Flexnet DC Monitor
Combiner Box
14 - REC REC260PE Z-Link Panels
14 - Deka 8G27 12V 99AH Batteries
Onan Quiet Diesel 12KW Genset
User avatar
Mike Curran
Forum Emperor
Posts: 2966
Joined: Sat Aug 28, 2004 6:28 pm
My RE system: Outback - Garage roof (2007/2017):
- 8 (2x4) Evergreen 180's into one FM80 (2007/2020 - replaced MX60)
- 6 (2×3) ALEO S79-300's into one FM80 (2017)
- 2 grid-tied VFXR3524A-01's series stacked, replaced GVFX's (2020)
- 12 Surrette/Rolls 2V x 1766Ah (2007)
- Hub10.3, Mate3s, FNDC, RTS. Tigo ES maximizers on each PV module.

Westinghouse Solar - Barn roof: (2012)
- 30 (2x15) 235W panels with Enphase M215 microinverters, grid-tied

Outback Skybox - Barn roof: (2019)
- 14 Talesun 275W in series (DC array input to SB inverter/charger)
- 3 SimpliPhi 3.8 batteries, 48V, 225Ah total
- AC coupled input from 14 Talesun 275W, Enphase M215 microinverters

Battery systems operate in grid-tied, net metering w/backup mode
All self-designed and self-installed
Location: Chagrin Falls, Ohio

Re: Autotransformer Question

Post by Mike Curran »

Maybe a dumb question but don't you need at least 4 inverters for a series/parallel setup? As in, 2 inverters in series, paralleled with two other inverters in series, like this:
Screenshot_20230122_153923_Adobe Acrobat.jpg
https://ei.tigoenergy.com/p/pZXn7SZQyO45
https://enlighten.enphaseenergy.com/public/systems/Hctc107221
raysun
Forum Emperor
Posts: 9378
Joined: Tue Jul 26, 2016 5:57 am
My RE system: Flexpower Two: (2) FXR3048A-01 - Series Stacked, (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
2 Midnite Solar MNPV6 combiners w/20A DC disconnects.
Honda EU7000is gas fuel generator
Off-Grid

Re: Autotransformer Question

Post by raysun »

Raysun- I read the link you provided, but not sure how precharge resistors relate to my question?
Sorry for the brevity of my post causing confusion. The message was to include your equipment list in your profile so we have a better picture of the system.

*EDIT* It's also a heck of a lot less confusing when I link to the proper post. I updated that.
🙄
Last edited by raysun on Sun Jan 22, 2023 2:59 pm, edited 1 time in total.
raysun
Forum Emperor
Posts: 9378
Joined: Tue Jul 26, 2016 5:57 am
My RE system: Flexpower Two: (2) FXR3048A-01 - Series Stacked, (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
2 Midnite Solar MNPV6 combiners w/20A DC disconnects.
Honda EU7000is gas fuel generator
Off-Grid

Re: Autotransformer Question

Post by raysun »

I'm still wondering if by using a autotransformer to balance the loads, if my system will be limited by the capacity of the autotransformer. Outback manual states that autotransformer is required when stacking series/parallel, but seems counterproductive of the purpose of stacking if wattage is limited.
I too purchased an X240 with the intent of providing 240V split phase from 120V inverter (and 120V backup generator) for our off grid system.
I ended up not installing it. Eventually I used "Classic Stacking" Dual inverters series stacked for 240V/60Hz Split Phase. The complications, losses, and limitations of the autotransformer didn't balance in my estimation with the notional idle efficiency and redundancy improvements the "Outback Stacking" scheme is designed to deliver. The X240 sits in a back corner of my power shed.
The series stacked dual VFX inverters idle at 1.4kWH/day total. A paltry sum in the scheme of a 7kW system.
Several forum members use the X240 and will attest to its stability and utility. Their path is more aligned with where you are planning to go. My choice was driven by the fact I really didn't need the component's functionality, and for me, KISS rules as I can easily wear the ***S mantle on occasion.
raysun
Forum Emperor
Posts: 9378
Joined: Tue Jul 26, 2016 5:57 am
My RE system: Flexpower Two: (2) FXR3048A-01 - Series Stacked, (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
2 Midnite Solar MNPV6 combiners w/20A DC disconnects.
Honda EU7000is gas fuel generator
Off-Grid

Re: Autotransformer Question

Post by raysun »

My next question is in regards to my array. I understand wiring the panels in series, parallel, etc. to achieve different configurations. It is my understanding that no matter how they are wired, the wattage is the wattage. Example..On the flexmate 80, the datasheet indicates a max array size of 1,500 watts on a 24v system. I have 260 watt panels, which means that no matter how they are wired, I can only use a max of 6 panels (260 X 6=1,560...actually a little over, but panels are never likely to be at 100% efficiency). Am I understanding this correctly?
A classic unintended consequence of a high power 24V system - smaller arrays must be used, and extra PV charger infrastructure is needed.
Is it possible to return the VFX2435 inverters in exchange for VFX4835 inverters? Life on the farm will be much better served starting with 48V.
For a reason entirely unrelated to the arrays, I suggest exchanging the FlexMax 60 for a 2nd FlexMax 80 as well. The reason is the one part likely to need replacement way down the dusty road is the charge controller cooling fan. An inexpensive and trivial operation in the FM80, and more akin to doing self-gall bladder surgery in the FM60.
On to the question you actually asked...
Not sure what spec sheet is being read, but an FM80 can accept a 2000 watt array (measured at STC) @ 24V (4000W array @ 48V). The REC 260s are 260W (STC) so 6 panels (2Sx3P) fits well under the 2kW limitation. The FM60 can accept a 1500W array so 4 panels (2Sx2P). That leaves 4 panels unused of your 14.
At 48V, a single FM80 could handle all 14 panels in 2Sx7P configuration.
Last edited by raysun on Sun Jan 22, 2023 2:14 pm, edited 3 times in total.
User avatar
Mike Curran
Forum Emperor
Posts: 2966
Joined: Sat Aug 28, 2004 6:28 pm
My RE system: Outback - Garage roof (2007/2017):
- 8 (2x4) Evergreen 180's into one FM80 (2007/2020 - replaced MX60)
- 6 (2×3) ALEO S79-300's into one FM80 (2017)
- 2 grid-tied VFXR3524A-01's series stacked, replaced GVFX's (2020)
- 12 Surrette/Rolls 2V x 1766Ah (2007)
- Hub10.3, Mate3s, FNDC, RTS. Tigo ES maximizers on each PV module.

Westinghouse Solar - Barn roof: (2012)
- 30 (2x15) 235W panels with Enphase M215 microinverters, grid-tied

Outback Skybox - Barn roof: (2019)
- 14 Talesun 275W in series (DC array input to SB inverter/charger)
- 3 SimpliPhi 3.8 batteries, 48V, 225Ah total
- AC coupled input from 14 Talesun 275W, Enphase M215 microinverters

Battery systems operate in grid-tied, net metering w/backup mode
All self-designed and self-installed
Location: Chagrin Falls, Ohio

Re: Autotransformer Question

Post by Mike Curran »

Mike Curran wrote: Sun Jan 22, 2023 12:39 pm Maybe a dumb question but don't you need at least 4 inverters for a series/parallel setup? As in, 2 inverters in series, paralleled with two other inverters in series, like this:Screenshot_20230122_153923_Adobe Acrobat.jpg
Never mind :oops:
Screenshot_20230122_163204_Drive.jpg
https://ei.tigoenergy.com/p/pZXn7SZQyO45
https://enlighten.enphaseenergy.com/public/systems/Hctc107221
raysun
Forum Emperor
Posts: 9378
Joined: Tue Jul 26, 2016 5:57 am
My RE system: Flexpower Two: (2) FXR3048A-01 - Series Stacked, (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
2 Midnite Solar MNPV6 combiners w/20A DC disconnects.
Honda EU7000is gas fuel generator
Off-Grid

Re: Autotransformer Question

Post by raysun »

14 - Deka 8G27 12V 99AH Batteries
A question not asked, with an answer not likely to be the all that great to hear...

The 14 12V@99AH monoblocs configure into a 24V battery as 2 monoblocs in series x 7 branches in parallel. A generally accepted rule of thumb is to limit a battery to 3 branches in parallel. The reasoning behind it is very small electrical imbalances between branches result in eventual chemical imbalances in battery cells. The end result is shorter battery service life. Valve Regulated Lead Acid (sealed) batteries are most susceptible to the cell imbalance effects.
Battery cabling designs that maintain the least variation between parallel branches helps, but does not eliminate the issue.
The most effective solution is to reconfigure for 48V (and employ 12 of the 14 monoblocs), but that requires 48V inverters.
The pragmatic solution is deploy as initially designed and live with the fact the battery will likely need replacing within 5 years.
There's a lot of maintenance two-step dances folks do with large parallel branch batteries: swapping monoblocks within the battery like some kind of back-breaking tire rotation, buying battery balancer widgets, buying black-box magic rejuvenating chargers; but in practice all those are so much snake oil, IME. Better to save up the $, use it to prospect for petroleum oil, and when you hit a gusher, use the $$$ to buy a lithium battery as a replacement.

Please take the above as advice worth the 0 cents you paid for it
Bryant
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Re: Autotransformer Question

Post by Bryant »

Raysun-

I greatly appreciate you taking the time to address my questions.

Sounds like a 48v system would better suit my intentions. Unfortunately, I purchased the equipment used from two separate individuals and so for the time being, I will likely keep what I have. One setup I have is a FlexPowerOne system, the other is individual components. Doesn't appear that it will be that difficult to change the flexpowerone wiring to stack the inverters.

I was unaware of the issue you describe with the parallel batteries. I will do some reading, but batteries are new and already purchased so I'll just live with the issue. If all works as planned, I'll probably be ready to switch to LiPo batteries before five years anyhow.

Thanks again. I'll likely have a few more questions when I start bringing everything online.
Bryant
raysun
Forum Emperor
Posts: 9378
Joined: Tue Jul 26, 2016 5:57 am
My RE system: Flexpower Two: (2) FXR3048A-01 - Series Stacked, (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
2 Midnite Solar MNPV6 combiners w/20A DC disconnects.
Honda EU7000is gas fuel generator
Off-Grid

Re: Autotransformer Question

Post by raysun »

It's all good gear and will serve you well. The great thing about Outback equipment is its built like a tank, and just keeps running.
The FlexPower One is a great foundation for the system. It has all the pieces needed for a highly available and easily operated system. Especially important for a quality system - all the necessary Balance of System (BoS) components are installed.
Integrating the 2nd VFX and FM60 into the FP1 is doable. Take this from someone who's done it (and swore an oath never to do it again), there's some lessons learned that will be gladly shared to make the project go much easier.
There's some methods to maximize battery life too. The things going for it is gel electrolyte is pretty stable - as long as it isn't overcharged. With the size of the battery there's little danger of that. Use the C20 rating as the AH capacity (88AH - round up to 90AH if new). MK/DEKA specify a charge rate of 30% of C20 so 27A per parallel branch x 7 branches is max charge current of around 185A. Good thing about gel AGM is they charge fast and efficiently (for lead).
The FM charge controllers are going to tolerate a bit of "cheating" regarding the solar solar arrays. Since there's 80A protection going into and out of the FM80, it will handle 8 panels. If analogous protection is installed for the FM60, it should handle the other 6.
Bryant
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Re: Autotransformer Question

Post by Bryant »

Great info. Thanks again!

I believe I found my answer regarding the autotransformer, and makes perfect sense once I read it...regarding load balancing, the max wattage the transformer would ever handle, is 1/2 the capacity of the system. (Balancing one leg to the other). Since each inverter is max 3,500 watts, the transformer would never balance more than that from one leg to the other. That being said, the 4k transformer is more than adequate.

One last question: (for tonight, anyhow!)
Regarding connecting the battery bank to the inverters, is it acceptable to connect two pos and neg cables (one set to feed each inverter) to the same pos and neg battery lugs, or should each inverter be fed from opposite ends of the parallel bank? (or does it make any difference)

Bryant
raysun
Forum Emperor
Posts: 9378
Joined: Tue Jul 26, 2016 5:57 am
My RE system: Flexpower Two: (2) FXR3048A-01 - Series Stacked, (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
2 Midnite Solar MNPV6 combiners w/20A DC disconnects.
Honda EU7000is gas fuel generator
Off-Grid

Re: Autotransformer Question

Post by raysun »

Well done on the Autotransformer research. It's a complex circuit from the conceptual standpoint.
One last question: (for tonight, anyhow!)
Regarding connecting the battery bank to the inverters, is it acceptable to connect two pos and neg cables (one set to feed each inverter) to the same pos and neg battery lugs, or should each inverter be fed from opposite ends of the parallel bank? (or does it make any difference)
There are two basic methods to connect the parallel branches in a battery. I'll call them "Daisy chaining" and "Bus".
Screenshot_20230122-201929.jpg
This is an illustration of daisy chaining the parallel branches. The branch-to-branch connections are easy and economical to make, but they carry an inherent condition that impacts battery life. The impedance between the branches will each be different. No matter how the battery is charged or discharged, (as illustrated, or with the feeds at opposite ends of the battery) the current flow between the branches will be imbalanced so the state of the cells within the branches will be imbalanced with respect to the others. The imbalanced state reduces service life materially.
Screenshot_20230122-201743.jpg
A better method is to connect each parallel branch in the battery using electrically identical cabling to each, and attaching the cables to common + and - bus bars. The charge and discharge currents to each branch is substantially more balanced using this method.

Given the number of branches in the battery, and the number of devices that will be attached (two inverters and two charge controllers) it will make sense to have multiple bus bars. The Battery Terminal Bus Bars (BTBB) for the battery configuration. In your case the BTBB will have 8 + terminals on one physical distributor and 8 - terminals on the other with 7 terminals for the battery, and the 8th to feed the Equipment Battery Bus, essentially a + and - bus bar pair in or adjacent to the DC wiring panel.
raysun
Forum Emperor
Posts: 9378
Joined: Tue Jul 26, 2016 5:57 am
My RE system: Flexpower Two: (2) FXR3048A-01 - Series Stacked, (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
2 Midnite Solar MNPV6 combiners w/20A DC disconnects.
Honda EU7000is gas fuel generator
Off-Grid

Re: Autotransformer Question

Post by raysun »

You are going to find yourself installing a lot of DC cabling to connect the battery and components. For all those cables, I use these folks: https://www.batterycablesusa.com/battery-cables
It's easy specifying cables on their site, the fabrication is 1st class, fast, and cheaper than I can do it myself. $4 pays for Priority Mail shipping for the entire order.
Bryant
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Re: Autotransformer Question

Post by Bryant »

Thanks, Raysun. A lot of good information for consideration.

Another question. There will be times during summer months at my place, where my current draw will undoubtedly exceed my solar capacity. When running the generator, I'm assuming the transfer switch inside each inverter will limit incoming AC to match inverter capacity (limited by breaker capacity also). In other words, if I know I will be exceeding 7,000 watts of draw, will I need to bypass the entire setup or can that much wattage pass through the transfer switches?
raysun
Forum Emperor
Posts: 9378
Joined: Tue Jul 26, 2016 5:57 am
My RE system: Flexpower Two: (2) FXR3048A-01 - Series Stacked, (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
2 Midnite Solar MNPV6 combiners w/20A DC disconnects.
Honda EU7000is gas fuel generator
Off-Grid

Re: Autotransformer Question

Post by raysun »

Bryant wrote: Mon Jan 23, 2023 9:18 am Thanks, Raysun. A lot of good information for consideration.

Another question. There will be times during summer months at my place, where my current draw will undoubtedly exceed my solar capacity. When running the generator, I'm assuming the transfer switch inside each inverter will limit incoming AC to match inverter capacity (limited by breaker capacity also). In other words, if I know I will be exceeding 7,000 watts of draw, will I need to bypass the entire setup or can that much wattage pass through the transfer switches?
Referring to the FlexPower One wiring scheme, take a look at the AC Output disconnect (circuit breaker) on the FP1 AC wiring panel. It should be rated 60A. Next notice it is physically ganged to an AC Output Bypass disconnect via a red mechanical lockout plate. Finally, check the AC Input disconnect, it too should be rated 60A. There are two modes of operation.

In "Normal" operation, when AC Input (from generator for off-grid) is accepted at the inverter AC IN terminals, the internal transfer switch routes the current to AC OUT. At the same time, the inverter switches to charger mode, and accepts AC Input current for that purpose. The AC transfer switch in the FX inverter is rated 60A @ 120V.

In "Bypass" operation, the inverter AC Output disconnect is open, and the AC Bypass disconnect is closed. AC Input from the generator is routed directly to AC Output. The AC Bypass disconnect is rated 60A @ 120V. In Bypass, AC Input continues to be fed to AC IN (for charging) unless the AC Input disconnect is open.
Screenshot_20230123-073417.jpg
https://www.outbackpower.com/downloads/ ... f-grid.pdf

For dual inverter operation, the FlexPower Two wiring scheme will need to be emulated. The FP2 uses dual ganged disconnects, each rated 60A @ 120V for a total of 60A @ 240V.
Screenshot_20230123-080723.jpg

FX SERIES INVERTER/CHARGER - Outback Power https://www.outbackpower.com/downloads/ ... nstall.pdf
Attachments
Screenshot_20230123-074414.jpg
raysun
Forum Emperor
Posts: 9378
Joined: Tue Jul 26, 2016 5:57 am
My RE system: Flexpower Two: (2) FXR3048A-01 - Series Stacked, (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
2 Midnite Solar MNPV6 combiners w/20A DC disconnects.
Honda EU7000is gas fuel generator
Off-Grid

Re: Autotransformer Question

Post by raysun »

Tossing this out there as things are in the planning stage...
I started with a FlexPower One (FP1) pre-wired panel for my first installation. It's a slick setup and worked great. Then I added a 2nd FM80. Working in the cramped confines of the small (FW100) DC wiring panel to add the 2nd Array disconnect, upgrade to a dual GFDI FM80 disconnect, and shoehorn in the attendant cabling was a royal PITA. I managed it, but swore never again! 🤪
When it came time to add a 2nd inverter, I sold the FP1 and bought an FP2. It was, of course, pre-wired with everything I needed. Had I chosen to keep the FP1, I would have replaced both the AC and DC wiring panels with the FW500 versions on the FP2. The added space for disconnects (circuit breakers), wiring, and the included bus bars are much needed for the job, IME.

20230123_111731.jpg
A panorama of the FP2. Note the horizontal inverter orientation to accommodate the larger FW500 AC panel on the left and the FW500 DC panel on the right. (Deadfront panels removed from the AC and DC FW500s to show the "innerds".)
Last edited by raysun on Mon Jan 23, 2023 10:22 pm, edited 3 times in total.
raysun
Forum Emperor
Posts: 9378
Joined: Tue Jul 26, 2016 5:57 am
My RE system: Flexpower Two: (2) FXR3048A-01 - Series Stacked, (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
2 Midnite Solar MNPV6 combiners w/20A DC disconnects.
Honda EU7000is gas fuel generator
Off-Grid

Re: Autotransformer Question

Post by raysun »

FP2 - AC wiring panel. (Deadfront cover removed to show a bit of the inside.)
20230123_111856.jpg
Wired for dual inverter and supporting 240V split phase AC. Note the ganged AC OUT / AC BYPASS assembly. Dual single pole AC Input disconnects. (Also a dual 30A disconnect for the X240 that isn't being used.)
20230123_111908.jpg
A peek inside, showing the AC wiring and bus bars. For 240V split phase: L1, L2, N, and G bus bars.
Lower half of panel not shown.
raysun
Forum Emperor
Posts: 9378
Joined: Tue Jul 26, 2016 5:57 am
My RE system: Flexpower Two: (2) FXR3048A-01 - Series Stacked, (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
2 Midnite Solar MNPV6 combiners w/20A DC disconnects.
Honda EU7000is gas fuel generator
Off-Grid

Re: Autotransformer Question

Post by raysun »

FP2 - DC wiring panel.

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Dual disconnects for Inverter Master (Battery feed cables), Array Input, FNDC and disconnect, FM80 output (Dual GFDI), (unlabeled,far left) 80A disconnect for external AC battery charger.

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DC panel lower half.
Note the equipment battery (+) bus plate. (On right.)

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DC panel upper half.
Note the equipment battery (-) bus plate with 3 FNDC shunts attached. Shunt A: (lower center) inverters, Shunt B: (upper left) charge controllers, Shunt C: (upper right) external AC battery charger.
The FP1 has two shunts installed. That's all you need.
Adding the 2nd set of VFX and FM power cabling will be a chore in the FP1.
Last edited by raysun on Tue Jan 24, 2023 8:21 am, edited 1 time in total.
provo
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Re: Autotransformer Question

Post by provo »

Thanks for those pix and descriptions -- beautiful!

Now in a folder on my Mac called "Raysun's FP2 photos". Outback should include a similar collection for all their products somewhere on the website. "Picture worth 1000 words" and all :grin:
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