Over paneling the FM80

ApicaApica Registered Users Posts: 32 ✭✭
What are your thoughts? 

I am currently using a 24V off grid setup that consists of 6 260 Watt Panels connected in 2 strings of 3 panels wired to a combiner box. Under perfect conditions which may never happen that would produce 1560 Watts. The FM80 manual states that the 24V system should not exceed 2000 PV Watts.

I now require more pv wattage now that the sun hours are less at this time of year. I purchased 2 270W panels to add to my setup because the 260W panels are not available However a CC Stats check revealed that my FM80 has seen a Max Wattage of 2048W. I have never used this CC on any other system how is this possible?

Based on these findings should I risk adding the extra panels?

1500W Samlex 24V Inverter . 2370 Watts Total Intenergy Panels . Flexmax 80A  . 8 Trace 6V 255AH Batteries Wired Series/Parallel for 24V . Trimetric 2030 . Midnite E-Panel. Tycon Tpdin Remote Monitor.
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Comments

  • icarusicarus Solar Expert Posts: 5,400 ✭✭✭✭
    edited November 2019 #2
    Most CC will simply “clip” excess production to protect the CC from over current.  That said, if you are running up against the limit quite frequently, instead of “throwing away power” via clipping, consider a larger controller, or a pair of controllers.  The 2000 watt PV limit is a matter of exceeding the 80’s 80 amp design limit.  Consider this...1560 watts of PV plus the extras is 2100 watts.  At 80% nets out to be ~1680 watts, into 27 vdc that would be ~62 amps. Into 24 vdc that would be ~70 amps.  I’m guessing the 2048 peak wattage was short lived edge of cloud event, should have produce just under ~76 amps at 27vdc. 

    My opinion, and it is worth every penny you pay for it...unless you have consistently very low battery voltages and or very cold temps coupled with lots of reflection off of snow, I would think the CC would be fine.  That said, I wouldn’t argue with outbacks documentation, but I will say there is a lot of conversation about this issue on the OB forum:  

    http://www.outbackpower.com/forum/viewtopic.php?f=29&t=8866&p=50467&hilit=Current+limit#p50467

    I’ll let other opine.  

    T
  • jonrjonr Solar Expert Posts: 1,379 ✭✭✭✭
    I believe the FM80 specs say "NEC Recommended Solar Maximum Array STC Nameplate".    I would follow the specs.

    I am available for custom hardware/firmware development

  • Dave AngeliniDave Angelini Solar Expert Posts: 5,287 ✭✭✭✭✭
    Pretty common since the days of solar began to overpanel. Usually 20 percent or so. We did this in 1978 at HP. 
     As long as you are not in a metal shed in the desert. Even if you were, if it is offgrid, current limiting probably will not happen more than once a day for a short time.
    "we go where power lines don't" Sierra Mountains near Mariposa/Yosemite CA
     http://members.sti.net/offgridsolar/
    E-mail [email protected]

  • VicVic Solar Expert Posts: 3,017 ✭✭✭✭
    Personally would follow OB's recommendation.   (as jonr mentioned).

    It appears that the FM80 & FM60 have a relatively slow-acting  output Current Limit (partially based on these CCs having a maximum input Isc Limit).   For the FM80,  the maximum total Isc input Limit is 64 A,  which would be difficult to exceed with PV strings of 3.

    Have never run any OB FM series CCs,   but it seems that OB should know best about their product  application specs.

    All IMO,   FWIW,  etc,    Vic
    Off Grid - Two systems -- 4 SW+ 5548 Inverters, Surrette 4KS25 1280 AH [email protected], 11.1 KW STC PV, 4X MidNite Classic 150 w/ WBjrs, Beta KID on S-530s, MX-60s, MN Bkrs/Boxes.  25 KVA Polyphase Kubota diesel,  Honda Eu6500isa,  Eu3000is-es, Eu2000,  Eu1000 gensets.  Thanks Wind-Sun for this great Forum.
  • MakersMakers Registered Users Posts: 16 ✭✭
    how do you plan to add, the panels in your system, (strings panels?)

  • wellbuiltwellbuilt Solar Expert Posts: 479 ✭✭✭
    I think you would be fine you would only be over a little bit . 
    Im sure you are not seeing 2000 watts in day to day use , I’m  a bit over 4000 watts @ 4425 
     on my 48 volt system and it’s working fine
     I use 12 panels most of the year . 
     If I need extra power I turn on my 5th string .
     I have a small fan blowing on the cc and inverter it keep things cool 
    Out back  flex power one  with out back 3648 inverter fm80 charge controler  flex net  mate 16 gc215 battery’s 4425 Watts solar .
  • ApicaApica Registered Users Posts: 32 ✭✭
    Makers said:
    how do you plan to add, the panels in your system, (strings panels?)

    I finally got around to reconfiguring my panels this morning. Originally I had (6) 260W panels wired in 2 sets of 3's to a combiner box leading to the FM80 and 1 set of (3) 270W panels wired in series to a FM60. 

    The new configuration now consists of a the wiring from the combiner box (6 panels)  wired to another combiner box on a breaker with the other set of 3 panels on another breaker. I now have 9 panels with a total wattage of 2370W wired to a single FM80.


    Today the maximum wattage produced was 2043W and 73.9A. 

    Is this safe?

    1500W Samlex 24V Inverter . 2370 Watts Total Intenergy Panels . Flexmax 80A  . 8 Trace 6V 255AH Batteries Wired Series/Parallel for 24V . Trimetric 2030 . Midnite E-Panel. Tycon Tpdin Remote Monitor.
  • wellbuiltwellbuilt Solar Expert Posts: 479 ✭✭✭
    Seams ok to me , the engineers  that sell the equipment all over panel a little , I’m not sure if it’s good or bad but I’m not having a problem with it at all . 
    I I have 15 295 watt panels 4425 watts I see 3700 watt every once and a while , the fan only comes on in the summer when it’s hot here mid 70s low 80s the controller is never hot to the touch . 
     I do turn off a string for a few months mid summer  , all winter it is really a non issue for me .  It’s snowing all the time 
    Out back  flex power one  with out back 3648 inverter fm80 charge controler  flex net  mate 16 gc215 battery’s 4425 Watts solar .
  • 706jim706jim Solar Expert Posts: 344 ✭✭✭
    I've purchased an FM80 and will be putting my 2kw of panels into it at 24 volts. But of interest is the fact that my old Trace C40 has seen 58 amps briefly and 50 continuously and still worked. It was getting a little hot though.
    Island cottage solar system with 2400 watts of panels, 1kw facing southeast 1kw facing southwest 400watt ancient Arco's facing south.Trace DR1524 MSW inverter, Outback Flexmax 80 MPPT charge controller 8 Trojan L16's. Insignia 11.5 cubic foot electric fridge. My 27th year.
  • Dave AngeliniDave Angelini Solar Expert Posts: 5,287 ✭✭✭✭✭
    Just keep an eye on it in summer. Make sure the fans sound good, an extra fan blowing in the area if over 80F is not bad.
    24V  does push the cooling when over paneled. Lots of good history on your side.
    "we go where power lines don't" Sierra Mountains near Mariposa/Yosemite CA
     http://members.sti.net/offgridsolar/
    E-mail [email protected]

  • ApicaApica Registered Users Posts: 32 ✭✭
    Just keep an eye on it in summer. Make sure the fans sound good, an extra fan blowing in the area if over 80F is not bad.
    24V  does push the cooling when over paneled. Lots of good history on your side.



    Daily temperatures here in Jamaica are usually in the 80F range, today it's 86F. I always use a fan to keep the equipment cool all year round.

    I'll keep an eye on things and update periodically.

    1500W Samlex 24V Inverter . 2370 Watts Total Intenergy Panels . Flexmax 80A  . 8 Trace 6V 255AH Batteries Wired Series/Parallel for 24V . Trimetric 2030 . Midnite E-Panel. Tycon Tpdin Remote Monitor.
  • petertearaipetertearai Solar Expert Posts: 443 ✭✭✭✭
    I have 2200 watts on my fm80  set limit a little below that at 75 amps .
    Very rarely do i see over 80 amps .has been like this for 3 years , no issues ..... so far .
    I note that outback initially   specced the fm80 for 2500 watts , but on later versions of manual they reduced it  
    2225 wattts pv . Outback 2kw  fxr pure sine inverter . fm80 charge controller . Mate 3. victron battery monitor . 24 volts  in 2 volt Shoto lead carbon extreme batterys. off grid  holiday home 
  • Dave AngeliniDave Angelini Solar Expert Posts: 5,287 ✭✭✭✭✭
    It also matters on how you are using it?  If it is grid-tie the electronics are being banged at full output continuously when the sun is out. 

    Offgrid, it probably is never near that for very long.  Especially if there is morning sun on the array when the electronics and air are cooler.
    "we go where power lines don't" Sierra Mountains near Mariposa/Yosemite CA
     http://members.sti.net/offgridsolar/
    E-mail [email protected]

  • ApicaApica Registered Users Posts: 32 ✭✭
    I have the amp limit set to 64 amps but yesterday the FM80 put out a maximum of 2275 Watts and 79.3Amps. 


    I thought setting the charge current would prevent a higher output from occurring.
    1500W Samlex 24V Inverter . 2370 Watts Total Intenergy Panels . Flexmax 80A  . 8 Trace 6V 255AH Batteries Wired Series/Parallel for 24V . Trimetric 2030 . Midnite E-Panel. Tycon Tpdin Remote Monitor.
  • Dave AngeliniDave Angelini Solar Expert Posts: 5,287 ✭✭✭✭✭
    It may not work that close to 80 adc. Was that a peak or continuous?   Ask Outback? I never would limit one as they are not that expensive to replace. Try 50adc?
    "we go where power lines don't" Sierra Mountains near Mariposa/Yosemite CA
     http://members.sti.net/offgridsolar/
    E-mail [email protected]

  • ApicaApica Registered Users Posts: 32 ✭✭
    It may not work that close to 80 adc. Was that a peak or continuous?   Ask Outback? I never would limit one as they are not that expensive to replace. Try 50adc?
    That was a peak. I just saw a maximum of 2416W @ 87.5Amps.

    I'm going to disconnect one panel and see the results.
    1500W Samlex 24V Inverter . 2370 Watts Total Intenergy Panels . Flexmax 80A  . 8 Trace 6V 255AH Batteries Wired Series/Parallel for 24V . Trimetric 2030 . Midnite E-Panel. Tycon Tpdin Remote Monitor.
  • Dave AngeliniDave Angelini Solar Expert Posts: 5,287 ✭✭✭✭✭
    I doubt limit will respond to peak. The limit circuit is just for people who over panel for winter (alot) and want to reduce the heat for summer. The fm80 is designed to run 80 amps. If it had 100 amps of solid solar input and is limiting at 80, the extra heat from limiting (the heat has to go somewhere) even in a limit mode. The limit function to me is a designer decision for northern latitudes.

    I would not worry about an 87 amp peak in PR offgrid. 
    "we go where power lines don't" Sierra Mountains near Mariposa/Yosemite CA
     http://members.sti.net/offgridsolar/
    E-mail [email protected]

  • petertearaipetertearai Solar Expert Posts: 443 ✭✭✭✭
    Yes i think max on my one has been around 2700 watts . But assume momentary . But as off grid  i have no way of knowing . The mate doesn't show it in small enough slices .  
    2225 wattts pv . Outback 2kw  fxr pure sine inverter . fm80 charge controller . Mate 3. victron battery monitor . 24 volts  in 2 volt Shoto lead carbon extreme batterys. off grid  holiday home 
  • EstragonEstragon Registered Users Posts: 4,478 ✭✭✭✭✭
    My guess is the over-limit peak happens between mppt sweeps, say when the sun comes out from behind a cloud.  If so, it would only last for a few seconds and not result in overheating. 

    I also suspect at least some controllers limit current based on internal temp irrespective of a limit setting.  A controller in warm ambient at high altitude, for example, may not be able to run at sustained full output and limit if it's running hot.
    Off-grid.  
    Main daytime system ~4kw panels into 2xMNClassic150 370ah 48v bank 2xOutback 3548 inverter 120v + 240v autotransformer
    Night system ~1kw panels into 1xMNClassic150 700ah 12v bank morningstar 300w inverter
  • VicVic Solar Expert Posts: 3,017 ✭✭✭✭
    edited April 20 #21
    Vic said:

       ...   It appears that the FM80 & FM60 have a relatively slow-acting  output Current Limit (partially based on these CCs having a maximum input Isc Limit).   For the FM80,  the maximum total Isc input Limit is 64 A,  which would be difficult to exceed with PV strings of 3.

    All IMO,   FWIW,  etc,    Vic
    Off Grid - Two systems -- 4 SW+ 5548 Inverters, Surrette 4KS25 1280 AH [email protected], 11.1 KW STC PV, 4X MidNite Classic 150 w/ WBjrs, Beta KID on S-530s, MX-60s, MN Bkrs/Boxes.  25 KVA Polyphase Kubota diesel,  Honda Eu6500isa,  Eu3000is-es, Eu2000,  Eu1000 gensets.  Thanks Wind-Sun for this great Forum.
  • ApicaApica Registered Users Posts: 32 ✭✭
    Yesterday's log revealed a Maximum of 2580 Watts and 94.8Amps. I thought my 80Amp CC breaker would have tripped but it did not.
    1500W Samlex 24V Inverter . 2370 Watts Total Intenergy Panels . Flexmax 80A  . 8 Trace 6V 255AH Batteries Wired Series/Parallel for 24V . Trimetric 2030 . Midnite E-Panel. Tycon Tpdin Remote Monitor.
  • EstragonEstragon Registered Users Posts: 4,478 ✭✭✭✭✭
    Breakers and fuses have a "trip curve".  The shape and values vary but in general they will take more current for shorter times.  For example, an 80a may not trip at 95a in a brief (eg few second) surge but might trip at or under 80a sustained for hours.
    Off-grid.  
    Main daytime system ~4kw panels into 2xMNClassic150 370ah 48v bank 2xOutback 3548 inverter 120v + 240v autotransformer
    Night system ~1kw panels into 1xMNClassic150 700ah 12v bank morningstar 300w inverter
  • Dave AngeliniDave Angelini Solar Expert Posts: 5,287 ✭✭✭✭✭
    Outback uses the next size up for an 80 amp controller also.
    "we go where power lines don't" Sierra Mountains near Mariposa/Yosemite CA
     http://members.sti.net/offgridsolar/
    E-mail [email protected]

  • Raj174Raj174 Solar Expert Posts: 762 ✭✭✭✭
    I agree with Vic. The FM80 takes a few seconds to clamp down on the amperage, even above its 80 amp rating. Your FLA battery bank would not do well with consistent current above about 67 amps so setting the limit would be wise IMO. There will be higher peaks, but they're brief and shouldn't be a problem. BTW the FM80 is rated for its full output current up to 40°C.


    3600W PV, MNE175DR-TR, MN Classic 150, Outback Radian GS4048A, Mate3, 54.4V 195AH LiFePO4, Kohler Pro 5.2E.
  • ApicaApica Registered Users Posts: 32 ✭✭
    Estragon said:
    Breakers and fuses have a "trip curve".  The shape and values vary but in general they will take more current for shorter times.  For example, an 80a may not trip at 95a in a brief (eg few second) surge but might trip at or under 80a sustained for hours.
    That makes sense, thank you for sharing.
    1500W Samlex 24V Inverter . 2370 Watts Total Intenergy Panels . Flexmax 80A  . 8 Trace 6V 255AH Batteries Wired Series/Parallel for 24V . Trimetric 2030 . Midnite E-Panel. Tycon Tpdin Remote Monitor.
  • ApicaApica Registered Users Posts: 32 ✭✭
    Outback uses the next size up for an 80 amp controller also.
    So should I upgrade to a 100Amp double pole breaker then?
    1500W Samlex 24V Inverter . 2370 Watts Total Intenergy Panels . Flexmax 80A  . 8 Trace 6V 255AH Batteries Wired Series/Parallel for 24V . Trimetric 2030 . Midnite E-Panel. Tycon Tpdin Remote Monitor.
  • Dave AngeliniDave Angelini Solar Expert Posts: 5,287 ✭✭✭✭✭
    edited April 21 #28
    A single pole 100 adc breaker rated for 150 vdc would avoid a nuisance trip. If you have the Outback 100% continuous duty 80a breaker you are fine with #4 minimum output wiring.
    If you are there all the time you probably are fine for now. If you leave for significant periods of time and have refrigeration or cooling, I would do what Outback recommends.
    "we go where power lines don't" Sierra Mountains near Mariposa/Yosemite CA
     http://members.sti.net/offgridsolar/
    E-mail [email protected]

  • ApicaApica Registered Users Posts: 32 ✭✭
    A single pole 100 adc breaker rated for 150 vdc would avoid a nuisance trip. If you are there all the time you probably are fine for now. If you leave for significant periods of time and have refrigeration or cooling, I would do what Outback recommends.
    Got it, I do leave for significant periods and have refrigeration so I'll change the breaker just to be safe.

    I guess it makes sense to upgrade the existing 4AWG wiring to 2AWG.
    1500W Samlex 24V Inverter . 2370 Watts Total Intenergy Panels . Flexmax 80A  . 8 Trace 6V 255AH Batteries Wired Series/Parallel for 24V . Trimetric 2030 . Midnite E-Panel. Tycon Tpdin Remote Monitor.
  • BB.BB. Super Moderators, Administrators Posts: 30,741 admin
    2 AWG wire is "not fun".

    There is welding cable (very fine stranded cable)--But that generally is not good for temination in "standard" charge controller connections (solid or course stranded cable clamps well, fine strand usually needs proper crimp termination).

    Make sure you have room that you can route 2 AWG cable.

    -Bill
    Near San Francisco California: 3.5kWatt Grid Tied Solar power system+small backup genset
  • Dave AngeliniDave Angelini Solar Expert Posts: 5,287 ✭✭✭✭✭
    You only need #2 if the distance from the controller to the DC buss is long. If it is Outback distribution box and buss #4 is perfect.
    As Bill said #2 is "not fun"
    "we go where power lines don't" Sierra Mountains near Mariposa/Yosemite CA
     http://members.sti.net/offgridsolar/
    E-mail [email protected]

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