Advice on best way to setup my outback system

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Advice on best way to setup my outback system

Postby HondaLee on Sat Dec 15, 2018 10:28 am

Thank you in advance for sharing your knowledge!
I will start by telling you what outback equipment I own
FLEXmax 500 with model VFX3648 inverters
FLEXmax 250 with model GVFX3648 Inverter
Two FLEXmax 80 charge controllers
48vdc 500 amp hour agm battery bank
One solar array with 3500 watts with plans to install second array
I have grid power to my house with manual generator transfer switch
Goals: to reduce electric bill as much as possible and have backup power
What are my options to acomplish my goals with what I already own and what is the best way to set it up?
HondaLee
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Re: Advice on best way to setup my outback system

Postby Mike Curran on Sat Dec 15, 2018 8:42 pm

Based on my own experience and assuming you need 240volts AC, I would use the flexware 500 only - I don't know if or how the GVFX would work with your 2 VFX's. Unfortunately your VFX's cannot sell back to the grid so any time your PV exceeds your loads (and your battery is fully charged) your solar resource will be wasted. Also, if I understand VFX operation correctly your house will be running on either the grid (e.g.,when you have low battery voltage) or your battery but never both at the same time.

I am assuming your question is more toward how to set up the AC side as the DC seems pretty straightforward. You won't need your second FM80 until you install your second array as one FM80 can easily handle your 3500 watt array to a 48 volt battery.

If your battery and solar resource are sufficient to support your entire house and your house loads don't exceed the 2 VFX's throughput limit (50 amps AC apiece I believe), then wire as shown in attached one-line, with your 2 VFX3648's classic-stacked for 240 volts output and all house loads fed from the VFX's.
15449315058211874130072.jpg

If not sufficient then you might have to break out your essential loads to a separate auxiliary panel. This panel would be fed from your inverters as above while your remaining house loads are fed directly from the grid. I'd keep the generator/transfer switch at the input to the aux panel, which assures your essential loads have the generator as backup. However with this setup your non-essential house loads would have no backup power. This is how my system is wired.

Hope this helps, maybe at least a starting point for discussion.
http://www.tigoenergy.com/site.php?95b2dca2-ca6c
https://enlighten.enphaseenergy.com/public/systems/Hctc107221
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Re: Advice on best way to setup my outback system

Postby HondaLee on Sun Dec 16, 2018 9:55 am

Thanks mike for responding to my question. I was following you till you were talking about generator to aux panel. What I have done at present is pretty much what you described except I just disconnected circuits from main home breaker panel and wired them to outback ac panel breakers. The problem with this is I was trying to charge my Chevy volt and it wouldn’t charge and goes straight to fault. And I don’t know why.
I was reading that the Gvfx FLEXmax 250 could be wired into grid with a separate solar array thus lowering my electric bill for loads I can’t run through other inverters.
I called outback a few years back and they told me I could send my non grid tied inverters back to them and they would do a conversion on them to grid tied and send back and do it for free ,but now I’m reading they now charge for it.
This morning I looked at my FM 80 and saw something I had not seen before it said high VOC . I have 4 panels wired in series 3 at 37.5 and one at 36.6 so I’m not sure how it would get to high.
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Re: Advice on best way to setup my outback system

Postby Mike Curran on Sun Dec 16, 2018 2:30 pm

http://www.tigoenergy.com/site.php?95b2dca2-ca6c
https://enlighten.enphaseenergy.com/public/systems/Hctc107221
Mike Curran
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Joined: Sat Aug 28, 2004 6:28 pm
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Re: Advice on best way to setup my outback system

Postby HondaLee on Mon Dec 17, 2018 8:55 am

The FLEXmax 250 has its own mate3 and hub.
You think there should be any issue with long term with excess voltage to charge controller?
From what I have read the one 36.6 volt panel in each string should have reduced the 37.5 panels if anything.if it did go over it had to be very little over.
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Re: Advice on best way to setup my outback system

Postby Mike Curran on Mon Dec 17, 2018 11:00 am

VOC changes with temperature, it is not a fixed rating. The rated VOC is based on certain conditions that may differ once panels are mounted in the field. Assuming the VOC's you've cited are the manufacturer's ratings, you can expect them to change in operation and those voltages add up to being pretty close to the FM80's rated max, so you're going to exceed it occasionally.

All I know is your FM80 isn't meant to operate at inputs over 150 VDC, you're taking your chances. You don't say how your panels are arranged but you must have more than 4 to get 3500 watts. You might want to consider wiring them 3 in series × "x" number of similar strings in parallel.

As far as your flexware 250, again I don't know how you'd get its FM80 to coordinate charging with the flexware 500's chargers so a second battery bank might be best - unless someone else smarter than me thinks this could work. In any case I would not connect its AC output to the same circuits as the 500's output...

You've got an embarrassment of riches there :grin: - Mike
http://www.tigoenergy.com/site.php?95b2dca2-ca6c
https://enlighten.enphaseenergy.com/public/systems/Hctc107221
Mike Curran
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