outback charge controller (s)

Discussion in 'Off Grid Living' started by rsbhunter, Feb 3, 2012.

  1. rsbhunter

    rsbhunter Monkey+

    Ok, ordered my panels for the THIRD time...seems that when these companies tell you they have them in stock, and in one case, i was told they HAD SHIPPED, that honesty in their statements is optional, but, they are substituting 240 watt panels for the 235's they didn't have, good deal, IF these are really in stock and ship....Ok, i feel better now...I am getting 10 240 watt panels at 29.8 volts each for a 24 volt system, inverted to 110.....I am going to use OutBack componets....on the charge controllers, do i need to get 2 of the Flexmax 60's, as each is rated at 1800 watts, and the Flexmax 80 is 2500 watts, which leaves little safety room ...???? Thanks for any help
  2. DKR

    DKR Raconteur of the first stripe

    Is it shorter to New York or by bus?

    How are you planning to connect the panels to the battery bank?

    What knd of grounding system are you going to use? (No, really, you need one for the lighting protector)

    Do you plan on a divert load? (later heater, etc)

  3. BTPost

    BTPost Stumpy Old Fart,Deadman Walking, Snow Monkey Moderator

    The OutBack Flex60 and 80 are Rated by Output AMPs at the Battery Buss Voltage. If you have 2400 Watts of Solar Panels, at 27.0 Volts Battery Buss Voltage, you would have 86 Amps. This assumes that you would be getting 100% from your panels. That is not a reality in the Real World, in most cases. Therefore You could use a 80 Amp Charge Controller, but there would NOT be what I would consider a Safe Operating Headroom in the Max Current Rating. You could buy Two Flex 60s, or a better setup would be one 60 and one 80, and that would give you enough Safe Operating Headroom, plus room for a little more expansion. The Best Setup would be two 80s, which would allow for a Significant Expansion Capability, down the road. ..... YMMV...
  4. TnAndy

    TnAndy Senior Member Founding Member

    The specs on my FM60 is 1600w panel rating @24v, and the FM80 is 2400 @24v, per Outback manual. ( that may have changed to the 1800 and 2500 you say, but that's not what my edition of the manual says ).

    Personally, I'm running 1750w arrays on two FM60''s ( 3500 total ) and 2450w on an FM80.

    I've seen very brief spikes of 1650ish on my 1750 array, with very cold, snow covered landscape, and bright sun. Typically, the max, even down to 10 degrees is under 1600.

    The FM 80, I just put in this fall, and haven't seen it do over 2250ish.

    IF I were you, I'd put an FM80 on it and not worry about it.
    Nadja and rsbhunter like this.
  5. ghrit

    ghrit Bad company Administrator Founding Member

    I remain amazed at the additional light gathering that happens with snow. Albedo contributes quite a bit. Sunburn in the winter is more than possible. Thing is, the days are shorter, so direct sun is less effective. Albedo offsets that, but only slightly.
  6. rsbhunter

    rsbhunter Monkey+


    Well, i can't say i'm not happy about TnAndy saying to go with the FM80...it will save me alot of $$$$$. I did check the "actual" watt numbers on the PV-USA rating, and it shows that the watt output is really closer to 213 watts per panel...And i typed in the wrong numbers, the panels i had ordered were CS6P-230P's, and they are substituting CSP6-235-P's.....I should have a realistic out put of about 2100-2200 watts...Thanks for the advice, i would spend the money if i had to, but if i can safely run 2200 watts through the OutBack FM80, then i can put the money into the inverter, breakers anfd fuses, etc, etc....Thanks again for all the help...rsbhunter P.S. the numbers i came up with were from here:http://www.outbackpower.com/products/charge_controllers/flexmax/
    BTPost likes this.
  7. TnAndy

    TnAndy Senior Member Founding Member

    Yeah....they've upped the STC array rating now.....I "suspected" they had enough built in over engineering to handle it years ago, which is why I pushed my first two over the 1600 the manual said then....but it's good to see them confirm it.

    Also, if you notice they now have an "NEC" max array category.....which complies with the de-rating required by the National Electric Code, and is only 2000w on a 24v system.....SOooooo...if you have an inspector that has a clue about solar, you 'might' have to go by that....be aware of that possibility.

    IF you have snow, really cold ( like sub-zero ) temps, and bright clear days at high altitude, you're probably going to see very close to that 2500w rating, if not slightly over on those type days.
    rsbhunter likes this.
  8. Nadja

    Nadja RIP 3-11-2013 Forum Leader

    Hi all. I run Trace C-60's. I once had my solar all coming in on one C-60 and it was nailed by a spike in the winter. When I talked to my buddy at the solar store, he said I needed to break down my incoming into two seperate runs, and each of those runs into a c-60. 12volt. I have since had no problems, but have noticed on cold days with snow reflection, I by combing the two incomeing systems have seen it spike upwards of 80 amps. That would be enouth to take a a 60 amp controller. Besides, if I can come up with extra money this summer , intend to add more solar panels to my system. I have the room.
  9. rsbhunter

    rsbhunter Monkey+

    2500 MAX

    That is why i am thinking about the two controllers, FM60's...the land is located at 10,000 feet, in the southern most part of Colorado, and show's to be in the 2nd highest solar insolation zones...NOW, depending on the tree situation, and what can be cleared, it MIGHT be possible to get very close to unobstructed sun....will post a picture
    The picture that has the road going down the hill, my property is on the right side..Thanks for all the help....rsbhunter
  10. Nadja

    Nadja RIP 3-11-2013 Forum Leader

    rsb, try doing search's for the outback mmp60 charge controllers. You may be surprised what you can save that way. nadja
    rsbhunter likes this.
  11. rsbhunter

    rsbhunter Monkey+

    OutBack FM60's

    Think i will go with the 1 FM80 and (1) FM60, as per TnAndys statement about the NEC rating.....won't save a dime if the inspector says" missed it by that much!!" Plus, if the funds happen down the road, maybe i'll want to kick it up to 2.5-3K...Don't know if i'll ever need that much...Still want to live as simple as possible, but only time will tell... TnAndys statement about the single FM80 would probably prove out true(would be enough) but, if in the future, prices go even lower on the per watt price, i would add more...if i bite the bullet now, and have 140 amp capacity with the controllers, i can safely increase the panel amount(currently at 79 amps) by 32 amps (total 122), or 4 panels, 940 watts, totalling almost 3300 watts for the array... and i am looking at the OutBack VFX3524 inverter/charger...Are my numbers correct? Thanks again, rsbhunter
    BTPost likes this.
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