Coordination of output between multiple Flexmax controllers

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Coordination of output between multiple Flexmax controllers

Postby pss on Thu Jan 11, 2018 10:56 pm

I would like to know if anyone actually understands how the Mate3, Radian inverter and Flexmax CC's actually coordinate power output.
In my case, I have 3 Flexmax CC's connected to 3 individual arrays. Lets call them Array 1,2 and 3. And Flexmax 1,2 and 3. Sometimes in the day, power output from all three CC's are nearly identical (33% from each CC and array). But at other times of the day, with a nearly identical load, power out put will be the same, but say Flexmax 1 and 3 will be putting out 90% of the power and Flexmax 2 only 10%. I can look at other times and see Flexmax 2 and 3 putting out 90% and Flexmax 1 only 10%, even though all are in the Sun.
I have rebooted all three controllers, but it still happens.
So i wonder, does can anyone offer an explanation as to why the three controllers vary so much through the day in power output and shift it around in a random fashion through the daytime?
Oh yes, global charge controlling is on at the Mate and the battery parameters for all 3 Flexmax units are the same.
Thank you.
pss
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My RE system: 7800 watts in three strings, Flexmax 60 x 3, Radian 8046A, GLSC load center, Mate 3, Hub 10.3 and 900 Amp, 48V Trojan T105-RE battery bank.

Re: Coordination of output between multiple Flexmax controll

Postby Mike Curran on Fri Jan 12, 2018 9:55 am

My guess is you're coming up against some current limit - if all 3 of your FM60's were to run flat out you'd have 180A going into your battery plus inverter, and if your house loads are small that 180A may be more than what your battery is calling for at whatever stage of the charge cycle it's in. So one (or more) charge controllers have to cut back. Don't know how OB's system decides how to do this... :???:...but I'd guess that's what it's doing.
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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: Coordination of output between multiple Flexmax controll

Postby pss on Fri Jan 12, 2018 1:01 pm

Mike, thanks for your input.

I think the current load definitely has something to do with it. My system behaves as follows: If batteries are say below 92% charged, then the PV power will equal load + 3000 watts. As the batteries get closer to 100% charge, while still in bulk, the system PV power will equal load + 1500 watts. At 99-100%, the PV output will be load + ~500 watts and then we get into float stage.
I just don't understand how the heck the charge controllers work in concert to juggle their outputs.
Today, at load of 1500 watts + 3000 watts for charging my three controllers were outputting 80 amps combined.

It would be nice if Outback support could explain the coding behind this behavior and modifications we could make.
pss
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My RE system: 7800 watts in three strings, Flexmax 60 x 3, Radian 8046A, GLSC load center, Mate 3, Hub 10.3 and 900 Amp, 48V Trojan T105-RE battery bank.

Re: Coordination of output between multiple Flexmax controll

Postby hendrik krijt on Sat Jan 13, 2018 5:15 am

Hi pss,

I also have 3 charge controllers now, and see the same thing.
Even if you try to calibrate all 3 to the identical battery voltage, they still have differences between them. If they are aiming for absorb or float voltage, the first one to reach that voltage starts to throttle back. End of day I always see the same one supplying the most kwh's, same one always 2nd, and same one last. As load increases, they will at some stage all contribute max they can, or as sunlight decreases they all give it their max.

I have read about charge co-ordination, but as my system works o/k, i don't bother fiddelling with it!

Lots of South African Southern Sunshine to you all!

Hendrik Krijt
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Re: Coordination of output between multiple Flexmax controll

Postby ianMc on Sun Jan 14, 2018 8:10 am

Ok,

I also puzzled, is there a calculation to determine the maximum charge rate that the batteries will accept. I have 3 80amp charge controllers so the max charge rate on the the mate os set to 240 amps. I have 24x2v lead acid batteries for about 900amp hours. The max charge I have seen from the solar panels is about 11.5kw

Q

Ian
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My RE system: 58 x 170w Solar Panels Aprox 11000 Watts
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3x2 GVFX3048E ie 6000Wats Per Phase
24x2volt 1000 AMPH FLA Batteries
1x Mate 3
1x FlexnetDc
OpticsRe

Re: Coordination of output between multiple Flexmax controll

Postby Mike Curran on Sun Jan 14, 2018 9:34 am

ianMc wrote:Ok,

I also puzzled, is there a calculation to determine the maximum charge rate that the batteries will accept. I have 3 80amp charge controllers so the max charge rate on the the mate os set to 240 amps. I have 24x2v lead acid batteries for about 900amp hours. The max charge I have seen from the solar panels is about 11.5kw

Q

Ian

Ian - Per Rolls Battery, max charge rate for (their) FLA batteries (and I'd bet this is a good number for most all FLA's) is 20% of the C20 rating of your battery. If your battery's C20 rating is 900Ah then max would be 180A. - Mike
Screenshot_20180114-112919.png
Mike Curran
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Posts: 593
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: Coordination of output between multiple Flexmax controll

Postby ianMc on Sun Jan 14, 2018 11:45 am

Thanks Mike
ianMc
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Posts: 71
Joined: Mon Nov 17, 2014 12:30 pm
Location: Johannesburg, South Africa
My RE system: 58 x 170w Solar Panels Aprox 11000 Watts
3x FM80-150VDC
3Phase Power
3x2 GVFX3048E ie 6000Wats Per Phase
24x2volt 1000 AMPH FLA Batteries
1x Mate 3
1x FlexnetDc
OpticsRe

Re: Coordination of output between multiple Flexmax controll

Postby pss on Sun Jan 14, 2018 1:06 pm

Mike, i agree with your info. But I have been doing some thinking and if you set the charge rate per your calculations, you may possibly limiting your PV output depending on your load. I have experimented with increasing the charge rate above your calculations and I have improved the amount of amperage into my batteries over the course of the day. But the peak PV generated does not seem to increase, more like the earlier and later times in the day seem to have delivered more amperage into the batteries.

Now, this is just all my anecdotal observations that I make like this: If I start the day at 86% of full charge and reach 100% from PV, then increase the charge amperage rate and start the day at say 83%, do i still reach 100% charge at at what time. Usually, the most I can put into my bank in a day is 16% if i use the standard calculations. Voltages are still kept safe and the MPPT controller is supposed to "be aware" of the ease at which the battery bank takes a charge.

Just guessing how the whole thing works since this is a PV system charging and not an AC based electric charger.
pss
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Posts: 66
Joined: Mon Jul 24, 2017 8:40 am
My RE system: 7800 watts in three strings, Flexmax 60 x 3, Radian 8046A, GLSC load center, Mate 3, Hub 10.3 and 900 Amp, 48V Trojan T105-RE battery bank.

Re: Coordination of output between multiple Flexmax controll

Postby ianMc on Sun Jan 14, 2018 10:17 pm

Morning Mike

My apologies if I am a pain.

Is there place in opticsre where I can see the max peak amps to the batteries.

I can see the input per hour maxed out at 7.2 yesterday, and where the system backed off (See attachments below)

I am waiting for my meter to be changed so that I can feed into the grid.

You will notice that yesterday I produced about 40kwh, my tests show that if I can feed into the grid I can do about 60kwh per day

Screenshot 2018-01-15 07.11.29.png

Screenshot 2018-01-15 07.11.11.png
ianMc
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Joined: Mon Nov 17, 2014 12:30 pm
Location: Johannesburg, South Africa
My RE system: 58 x 170w Solar Panels Aprox 11000 Watts
3x FM80-150VDC
3Phase Power
3x2 GVFX3048E ie 6000Wats Per Phase
24x2volt 1000 AMPH FLA Batteries
1x Mate 3
1x FlexnetDc
OpticsRe

Re: Coordination of output between multiple Flexmax controll

Postby Mike Curran on Mon Jan 15, 2018 8:39 am

Ian - In Optics, click on device map, then on your FNDC device, then click on the shunt you're interested in, and it shows max charging current (for the current day, I think). The screen print I've attached is for my charger (GVFX3524) shunt A, showing max of 70.9A which I think occurred during an overnight refloat cycle. Hope this helps!
Screenshot_20180115-103106.png


Edit: I looked at my overnight kwh graphs and max I see is around 1kwh, compared to the 1.8kwh shown on the above attachment, so I suspect the data in the device map/fndc/shunt screen is historical max, not daily.

Maybe if you look at your kwh graph for your charge controller, pick the highest (hourly) figure, then divide that number by your system voltage, you can get an approximate max amps from your charge controller...and so on for your inverters.

PS Do you have a net metering agreement with your grid utility? That's going to be a lot of kwh fed back in! Here in Ohio we're not allowed/won't get compensated for excess net generation over an annual period - at year end, if we generated more than we used, the utility gets to keep the excess, free.
Mike Curran
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Posts: 593
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: Coordination of output between multiple Flexmax controll

Postby ianMc on Tue Jan 16, 2018 7:18 am

Hi Mike

This is like a comedy as I blunder around
- Shunt A (Solar Panels) max input 164 Amps
- Shunt B (Inverters) Max input 252Amps DC - Ouch
Screenshot 2018-01-15 17.47.31.png

Screenshot 2018-01-15 17.47.23.png


Regarding your second question re grid feedback, the real reason for me is not to get money from the utility but to preserve your batteries.
Basically as you know if you keep your batteries as close to possible to 100% they will last longer than if you discharge them to 50% every day.
So the object would be to net meter your usage to Zero and should there be an outage you batteries will be as close 100% as possible and hopefully your flipping expensive batteries will last forever

My Scenario is more tricky as I pay more to take from the grid than they pay me

Peak rate (06H00 -> 10H00 + 16H00 -> 120H00) Rx+60%
OFF peak RX
Feedback RX-50%

What I plan to do is come off the grid during peak and feed back during OFF peak hoping to Zero my bill and save my batteries.

In South Africa we have an expression JA, well no, well Fine (Yes,No OK) which sort of sums it up

Regards

Ian
ianMc
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Posts: 71
Joined: Mon Nov 17, 2014 12:30 pm
Location: Johannesburg, South Africa
My RE system: 58 x 170w Solar Panels Aprox 11000 Watts
3x FM80-150VDC
3Phase Power
3x2 GVFX3048E ie 6000Wats Per Phase
24x2volt 1000 AMPH FLA Batteries
1x Mate 3
1x FlexnetDc
OpticsRe

Re: Coordination of output between multiple Flexmax controll

Postby Mike Curran on Tue Jan 16, 2018 10:56 am

Hey Ian - Those are some kinda high charge rate maximums. Fyi, there's a screen in Optics/Device map/Mate/Global Charge that allows you to set the max charge rate from all sources. (Rolls says no more than 20% of your battery C20 rating).
Screenshot_20180116-124716.jpg

As far as your grid connection, wouldn't you be better off to stay connected during on-peak hours, when you're compensated more (and probably when your production is higher)? Here in Ohio we don't have time of use rates so no difference in price. Off peak is generally night time for us, if that's the same for you, seems like best time to disconnect, no? - Mike
Mike Curran
Forum Czar
 
Posts: 593
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: Coordination of output between multiple Flexmax controll

Postby ianMc on Tue Jan 16, 2018 12:27 pm

Thanks Mike

I belatedly made the adjustment you suggested above. When they change my meter I am going to do some experimentation.

Hmm, everytime I think that I have it waxed you make me rethink :grin: ](*,) ](*,)

My order of business is
- Make sure that I am ready for an extended outage ( Provided we have sun I can stay up indefinitely)
- Preserve my batteries as much as possible to avoid replacement for as long as possible
- Try to zero my account taking into account the stepped tariff and the fact that I don't really think that they will give me money back ( even though they say they will.)

I will let you know how it pans out

Regards

Ian
ianMc
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Posts: 71
Joined: Mon Nov 17, 2014 12:30 pm
Location: Johannesburg, South Africa
My RE system: 58 x 170w Solar Panels Aprox 11000 Watts
3x FM80-150VDC
3Phase Power
3x2 GVFX3048E ie 6000Wats Per Phase
24x2volt 1000 AMPH FLA Batteries
1x Mate 3
1x FlexnetDc
OpticsRe


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