Best panel config and settings for Outback 80 with LiFePO4

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Best panel config and settings for Outback 80 with LiFePO4

Postby McG on Tue Nov 14, 2017 2:13 am

Good day everyone.
I have had my Outback since 2008 and it's still going strong. \:D/ I am currently upgrading the solar array. What I need to find out is what will be a good (best) configuration to connect 12 x 100w solar panels to the Outback and what is best settings for charging LiFePO4?

I am currently contemplating connecting 6 panels in Series x 2 arrays and parallel them to the Outback. Any inputs will be appreciated.
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Re: Best panel config and settings for Outback 80 with LiFeP

Postby Mike Curran on Tue Nov 14, 2017 8:06 am

Check out these docs I got from SimpliPhi:



Last edited by Mike Curran on Thu Nov 16, 2017 6:52 am, edited 1 time in total.
Mike Curran
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My RE system: Outback:
- 8 (2x4) Evergreen 180's into one MX60
- 6 (2×3) ALEO S79-300's into one FM80
- 2 grid-tied GVFX3524's classic stacked for 120/240VAC
- 12 Surrette/Rolls 2V x 1766Ah
- Hub10.3, Mate3, FNDC, RTS, OpticsRE. Tigo Energy ES maximizers on each PV module.

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

Re: Best panel config and settings for Outback 80 with LiFeP

Postby McG on Thu Nov 16, 2017 12:19 am

Thanks Mike.
I am still waiting for comments regarding the panel configuration though: 2 sets of 6 panels in series or 12 panels in parallel? I guess 12 in parallel will push the Short Circuit Amps too high for the Outback FM80? :-k
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Re: Best panel config and settings for Outback 80 with LiFeP

Postby Mike Curran on Thu Nov 16, 2017 7:19 am

Hey McG - A lot depends on your system. You need the input voltage to your FM80 to be higher than your battery voltage, and by more than a couple volts. So if you're running a 12V battery that'll need equalization at 15.5V, your panel setup (series, parallel, whatever) should be rated to supply 24 volts, minimum. And so forth for a 24V battery, etc.

Also, the FM80 will fry if you supply it more than 150V from your PV so that limits the number of panels you can put in series.

Finally, with an FM80 output rating of 80A, a 12V battery system could accept a maximum of 80 × 12 = 960Watts of solar, a 24V battery system could take a max of 80 × 24 = 1920W, and a 48V battery, 80 × 48 = 3840W.

So if you want to use all your 1200 watts of your PV panels, you need a 24 volt battery, and your array output needs to be at least 48V (imo). 6 panels in series might exceed the FM80's 150V input limit, depends on your panels. At 100W apiece it might work, but again depends on panels. - Mike
Mike Curran
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Posts: 607
Joined: Sat Aug 28, 2004 6:28 pm
Location: Chagrin Falls, Ohio
My RE system: Outback:
- 8 (2x4) Evergreen 180's into one MX60
- 6 (2×3) ALEO S79-300's into one FM80
- 2 grid-tied GVFX3524's classic stacked for 120/240VAC
- 12 Surrette/Rolls 2V x 1766Ah
- Hub10.3, Mate3, FNDC, RTS, OpticsRE. Tigo Energy ES maximizers on each PV module.

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

Re: Best panel config and settings for Outback 80 with LiFeP

Postby McG on Thu Nov 16, 2017 10:42 pm

Thanks a lot for all the info Mike. Can you tell me why the input is limited to 80 x 12 = 960W?

My panel specs: 100W
Voc = 21.7
Isc = 6.1
Vmp = 17.7
Imp = 5.7

So I worked out that 6.1A x 2 = 12.2A which is sway within limits for FM80.
21.7V x 6 = 130V which is still 20V below FM80 limit.
That is why I thought to go 6 panels in series x 2 arrays.

Oh, and remember I have an 800Ah 12V lifepo4 battery which can apparently take as much as you can throw at it. :?:
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Re: Best panel config and settings for Outback 80 with LiFeP

Postby Mike Curran on Fri Nov 17, 2017 11:06 am

McG wrote:Can you tell me why the input is limited to 80 x 12 = 960W?


Power into the FM80 = power out, so with an 80A output limit into a 12V battery, input is limited to output = 960W. You can't put more power in than what the output limit is, or you'll exceed the output limit. I've attached 2 photos of an article from Home Power magazine that I used when I built my first system with an MX60 charge controller (rated for 60A output). Hope this helps. Break out your magnifying glass :grin: (sorry!)

15109414960131438733879.jpg

1510941598746-2010371026.jpg


Note Outback also has a string sizing tool on their website that can help you decide what array configuration is best. http://outbackpower.com/outback-support ... izing-tool

McG wrote:Oh, and remember I have an 800Ah 12V lifepo4 battery which can apparently take as much as you can throw at it. :?:
You'll only be able to throw 80A at it from your FM80 so unless you add more PV and another charge controller, your battery's capacity to accept a charge isn't really a factor. - Mike
Mike Curran
Forum Czar
 
Posts: 607
Joined: Sat Aug 28, 2004 6:28 pm
Location: Chagrin Falls, Ohio
My RE system: Outback:
- 8 (2x4) Evergreen 180's into one MX60
- 6 (2×3) ALEO S79-300's into one FM80
- 2 grid-tied GVFX3524's classic stacked for 120/240VAC
- 12 Surrette/Rolls 2V x 1766Ah
- Hub10.3, Mate3, FNDC, RTS, OpticsRE. Tigo Energy ES maximizers on each PV module.

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

Re: Best panel config and settings for Outback 80 with LiFeP

Postby McG on Sun Nov 19, 2017 3:09 am

Cheers for the info once again Mike. Being my second language, I do have a hard time understanding all the English jargon at times, like working out Vtoc and Vtmp. Any assistance would be appreciated. Normal average day temp is around 22 Centigrade and coldest is around 0.
Also, a question that's been bugging me for some time: You calculated max wattage as 80 x 12. Mu battery is normally r unning at 12.9V and charges up to 14.2. What voltage should I actually use for correctly calculating the max wattage? :-k
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Re: Best panel config and settings for Outback 80 with LiFeP

Postby Mike Curran on Sun Nov 19, 2017 10:04 am

Hey McG - Given what you have I wouldn't worry about exceeding the FM80 input voltage limit. Even with a 10% correction for low temperature, with 6 in series you're only at 143 volts and although that may seem like a slim margin, you'll rarely see input that high, at least that's been my experience.

http://www.outbackpower.com/downloads/d ... manual.pdf
(Btw OB's website has this document in other languages besides English, although you seem to be doing okay with it :grin: )

However, I would be concerned about max wattage into your FM80. If you look at the manual page 98, with a nominal battery voltage of 12 volts, max input is 1000W. There will be days when your panels meet or exceed their rated 100W × 12 output, and that's cause for concern. I know you don't want to waste your PV panels on hand but you might want to consider wiring them 2 parallel strings of 5 in series - and keep the last 2 panels as spares or until you upgrade your system. You could either add more panels and a second charge controller, or add a second battery in series to boost your system voltage to 24 volts (which would allow 2000W of PV input).

Hope this helps! - Mike
Mike Curran
Forum Czar
 
Posts: 607
Joined: Sat Aug 28, 2004 6:28 pm
Location: Chagrin Falls, Ohio
My RE system: Outback:
- 8 (2x4) Evergreen 180's into one MX60
- 6 (2×3) ALEO S79-300's into one FM80
- 2 grid-tied GVFX3524's classic stacked for 120/240VAC
- 12 Surrette/Rolls 2V x 1766Ah
- Hub10.3, Mate3, FNDC, RTS, OpticsRE. Tigo Energy ES maximizers on each PV module.

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

Re: Best panel config and settings for Outback 80 with LiFeP

Postby McG on Tue Nov 21, 2017 2:07 am

Now Mike, that deserves an =D>
It is my kinda English. I still wonder though, what would happen if the input wattage do go over, let's say to 1100W? That is like adding an extra 100W panel.

Copied from my last post: Also, a question that's been bugging me for some time: You calculated max wattage as 80 x 12. My battery is normally running at 12.9V and charges up to 14.2. What voltage should I actually use for correctly calculating the max wattage? :-k
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McG
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Posts: 13
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My RE system: 1kW Sunpower array input to FM80 wired to 800Ah LifePo4 Battery with BMS

Re: Best panel config and settings for Outback 80 with LiFeP

Postby McG on Tue Nov 21, 2017 2:07 am

Now Mike, that deserves an =D>
It is my kinda English. I still wonder though, what would happen if the input wattage do go over, let's say to 1100W? That is like adding an extra 100W panel.

Copied from my last post: Also, a question that's been bugging me for some time: You calculated max wattage as 80 x 12. My battery is normally running at 12.9V and charges up to 14.2. What voltage should I actually use for correctly calculating the max wattage? :-k
User avatar
McG
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Posts: 13
Joined: Mon Sep 27, 2010 2:36 am
My RE system: 1kW Sunpower array input to FM80 wired to 800Ah LifePo4 Battery with BMS

Re: Best panel config and settings for Outback 80 with LiFeP

Postby blackswan555 on Tue Nov 21, 2017 3:27 am

That is why I thought to go 6 panels in series x 2 arrays.
I would go the opposite, 2 in series, 6 arrays, You would yes, need larger cable but it is not far :smile: The advantages being you are running the FM closer to its best efficiency & you do not have 130v ish floating around, (you are also too close for my liking to FMs max VOC, Which even in a poor climate or day could be peaked with edge of cloud effect)

I still wonder though, what would happen if the input wattage do go over, let's say to 1100W? That is like adding an extra 100W panel.

The FM will limit its OUTPUT to 80amps no matter what you have incoming, So theoretically you could add as much as you want, If go over the 80a or run on the limit, it is advisable to rate cables and breaker at 100amp to avoid nuisance tripping,

Tim
My comments are based on my experience and research, They are not endorsed or checked by Outback.I am an independent British electrician living in Spain, So please take this into account when reading /acting on my post`s.
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Re: Best panel config and settings for Outback 80 with LiFeP

Postby Mike Curran on Tue Nov 21, 2017 8:58 am

This thread addresses maximum PV into a charge controller: viewtopic.php?f=29&t=8866

I guess the bottom line is you'll never get more than about 1000W from your FM80 into your 12V battery, but having more than 1000W of panels at the input may increase your energy harvest on cloudy days. My bad. :oops:

FWIW - Mike
Mike Curran
Forum Czar
 
Posts: 607
Joined: Sat Aug 28, 2004 6:28 pm
Location: Chagrin Falls, Ohio
My RE system: Outback:
- 8 (2x4) Evergreen 180's into one MX60
- 6 (2×3) ALEO S79-300's into one FM80
- 2 grid-tied GVFX3524's classic stacked for 120/240VAC
- 12 Surrette/Rolls 2V x 1766Ah
- Hub10.3, Mate3, FNDC, RTS, OpticsRE. Tigo Energy ES maximizers on each PV module.

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

Re: Best panel config and settings for Outback 80 with LiFeP

Postby McG on Fri Dec 08, 2017 12:32 am

Thanks Mike. Another question - I heard all kinds of stories about people fitting fuses before the controller and some at the panels etc. My old array didn't have fuses and was fine for 8 years.
If I do the 5 Series x 2, where will be the best place to fit a fuse/fuses and is it necessary? :-k
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McG
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Posts: 13
Joined: Mon Sep 27, 2010 2:36 am
My RE system: 1kW Sunpower array input to FM80 wired to 800Ah LifePo4 Battery with BMS

Re: Best panel config and settings for Outback 80 with LiFeP

Postby Mike Curran on Fri Dec 08, 2017 10:29 am

McG - This thread has some good advice from Kent Osterberg and Ravenswood regarding fusing for parallel battery strings:

viewtopic.php?f=1&t=9366&p=53072&hilit=Fuse#p53072

I can't comment from my own experience (haven't any :smile: ).
Mike Curran
Forum Czar
 
Posts: 607
Joined: Sat Aug 28, 2004 6:28 pm
Location: Chagrin Falls, Ohio
My RE system: Outback:
- 8 (2x4) Evergreen 180's into one MX60
- 6 (2×3) ALEO S79-300's into one FM80
- 2 grid-tied GVFX3524's classic stacked for 120/240VAC
- 12 Surrette/Rolls 2V x 1766Ah
- Hub10.3, Mate3, FNDC, RTS, OpticsRE. Tigo Energy ES maximizers on each PV module.

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


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