Need some solar help and advice

Discussion in 'Off Grid Living' started by T. Riley, Jul 24, 2016.

  1. Cruisin Sloth

    Cruisin Sloth Special & Slow

    OK live well
    If you read the breaker spec's & your NEC 2015 rules , & re thought as Im trying to get across , then maybe.
    Northern Arizona Wind & Sun Solar Forum
    another site to check up on. ASK WHY & many will jump to a answer
    Why are there breakers on the strings ? what is the reasoning?

    And how many strings do you have ?
  2. Texas Monkey

    Texas Monkey Monkey

    3 strings, 3 breakers, easy way to shut down some or all of the power coming into the charge controller, for regular maintenance and testing, The QO is a big quality metal box with breakers designed to last a century, that marine breaker just seemed too small and breakable.
    The QO panel was an afterthought once I realized I could not afford nor did I have enough space for enough panels to fully utilize the charge controller.

    six 158 watt 12v panels, hooked up in pairs on hinges on the roof of my school bus,
    feeds to the QO panel, which feeds to a 60 amp marine breaker, to a 60amp morningstar mppt, to a home made bus bar, trimetric 2025? meter with shunt for ammeter,
    Four trojan 12v 150ah batteries,
    The QO panel was an afterthought once I realized I could not afford nor did I have enough space for enough panels to fully utilize the charge controller.

    I have spent hours on that blog, the single best blog I like is handy bobs blog, he makes sense to me.
  3. Cruisin Sloth

    Cruisin Sloth Special & Slow

    SO Rules first !!
    2 stings of same value , No need for any breakers ( not wise due to adding or checking a string against another) , Three strings , then the rules kick in due to back feeding of two OR more strings into one that is the MAJOR .

    Kid (nice girl & boys ) wack a ball & it hits a roof , but your panels are in the way , crack & a short between cells length so the (im picking on yours !! 36 cell) gets shorted to 8cells but are fused so all power is going from 2 strings into one1 shorted string @ 8 cell broken & it starts to overheat on one panel .

    YOUR imp is 8.xx (never see that in TX ) but your breaker is 15 amps
    Series adds voltage / per panel , but AMPS are the same !!!
    SO now we have 2 series strings feeding a shorted panel 16 Amps , went the max currant out of each string is 8,xx (in a perfect world) times 2 , so just under (losses) 15 amps , breaker holds & roof is on fire !!

    OCB's /Breakers / Fuses/ Cut-outs are ONLY to protect the WIRE , NOT the appliance or supply ..

    Sloth ,

    IM saying your over breaker-ed in amps , I'd pick 10 amps & use the full 150Vdc range , (upgrading later if needed) and make sure the Feed is power in & the load is where the power is to go.
    NEC2015 states all breakers MUST be marked , So any old breaker , can be new IF you mark IT .

    Last edited: Sep 17, 2016
    Yard Dart likes this.
  4. Texas Monkey

    Texas Monkey Monkey

    My reading of NEC says your wrong,
    Other blogs seem to say your wrong, all the string breaker math I see on other blogs seem to say you are wrong,
    But your explanation of real life makes sense, I will change to 10 amp.
    Cruisin Sloth likes this.
  5. Yard Dart

    Yard Dart Vigilant Monkey Moderator

    Real world trumps all.... safety first at home.
  6. Cruisin Sloth

    Cruisin Sloth Special & Slow

    Sir & I mean SIR
    I know many ways to read that NEC2015 code book & the outcome can be taken in a few ways .
    I too have read a line or two & it can be taken a few different ways.
    I myself have been caught up on the "Wording" with Solar Installs as has many other .
    That Code book is written to confuse I Swear.
    When the Solar NEC courses were put on buy a few Suppliers , on every course , i heard the strangest questions from the folks taking the course's . Between the main suppliers putting on the course John & Mike (didn't learn the Sir names) we also had Robin Gudgel,BoB Gudgel,Ryan on the east side & Mario (all from Midnite Solar ) on the west on a few seminars.. Even the two who asked for the Midnite crowd to addend & speak didn't get all the solar stuff figured . Many a time the questions HAD to be answered by one of the Midnite gents due to They were working on the NEW B17 & had to comply with all the new regs SO THEY Understood them .
    In 12 courses I heard many of the same assumptions and misinterpretation of a few lines.

    So go back & read the lines and see if you can get a different meaning of the same line , I have & was shocked .
    Kinda like the witch & the pretty girl Pix , once i see the witch , I can't seem to find the pretty girl again.

    & be safe
  7. Yard Dart

    Yard Dart Vigilant Monkey Moderator

    The National Electrical Code is the minimum required for safety. Most jurisdictions enhance the requirements in one way or another, due to either their greater local concern in some aspect, or their reading/interpretation of the NEC. It is always best to A- consult with your local electrical inspector to determine what he/she will allow as a minimum install and B- over-build/protect your system to ensure safety for when Murphy introduces his "worst case real world scenario" to your homestead.
    Best of luck!!
    Cruisin Sloth likes this.
  8. Texas Monkey

    Texas Monkey Monkey

    A what if question,
    This stuff is mounted on a school bus, nothing but heavy gauge metal all around, on a roof all metal rack at least 6in above the metal roof.
    If one would have broken and the other two were feeding it at noon in august in texas, what would have happened, the panels came with 10 gauge cables which connect to my 8ga wires that feed the QO panel?
    Yard Dart likes this.
  9. Yard Dart

    Yard Dart Vigilant Monkey Moderator

    Nothing probably would have happened in that scenario... but always remember Murphy is waiting for an opportunity. :)

  10. Cruisin Sloth

    Cruisin Sloth Special & Slow

    Hail has also started a few fires if the protection is not installed . I like to have "Just enough" breaker amperage to cover the feed or supply load , the WIRE size I use is to stop voltage drop & makes little difference to the breaker size . The breakers I picked are for MY setup , im using 15amp /150Vdc with imp of 8.9Adc in a perfect day on 12/4 split strings 42Kw .. Also since Im above the 49* Lat , I have 4.2mm thick glass & that needs a roof structure to hold a bit more weight.

    One other there thing is wind speed,, if your doing 50mph in a 50 mph storm & your driving into it ,your wind speed is 100mph & those panels might not be rated that high. What some do is use a few internal underside braces & double sided tape to help stiffen the glass from the underside .




  11. T. Riley

    T. Riley Monkey+++ Site Supporter++

    I have one more question for this thread. My solar is for backup. SHTF and power outages. How do I maintain the batteries best. I can disconnect the panels from the charge controller and the controller from the battery bank. I am at my BOL 2-3 days a week. While I am here I have been connecting everything up and disconnecting when I leave. Occasionally I will put a load on and draw the batteries down 30-40%. I have no idea what is best. Need advice. Thanks.
  12. Cruisin Sloth

    Cruisin Sloth Special & Slow

    bug out place should be on 24-7-365.4
    Whats the CC & battery amp hr size &type

  13. T. Riley

    T. Riley Monkey+++ Site Supporter++

    Cruisin Sloth likes this.
  14. BTPost

    BTPost Stumpy Old Fart Snow Monkey Moderator

    Just did NOT let them Freeze.... That will destroy an AGM Battery....
  15. Cruisin Sloth

    Cruisin Sloth Special & Slow

    Working them or as you put it :
    Just float them .
    Cell info :

    Vmaxtanks specializes in the manufacturing of high quality AGM deep cycle batteries. These batteries offer superior performance and 10-12 years life span in float mode. MAX. CHARGING CURRENT: 35A MAX. CHARGING VOLTAGE: 14.7V RECOMMENDED: 15A, 14.5V CHARGER: SMART/MICROPROCESSOR CONTROLLED CHARGER!

    So what is the solar unit ? Im saying a KID or a Brat would be good !
    How are they strung ? 12,24,48Vdc ??

    Constant Float in grid tie ,I'd set at 14.2 within a 24 equ cycle per year , Solar , my settings would be on Voltage & panel & CC type . Not one set answer off grid.

    Last edited: Sep 26, 2016
  16. T. Riley

    T. Riley Monkey+++ Site Supporter++

  17. Cruisin Sloth

    Cruisin Sloth Special & Slow

    OK < Sorry
    I though you hade a few solar places , home & BOP .
    So for the FM80 set max float 14.5 Vdc if you also have a battery temp sender for the FM80 & let it look after the cells Eq at 14.7 every month if its mostly sitting idle . you can limit the max charge out of the fm80 , but if you do have a BTS , let it limit temp charge. That way if you do load the system during sunny noon , the FM might be able to supply all the inverter draw .
    Since your an Outback FM80 , Wizbang Jr & shunt controlling is out . KID & Classic you could limit 30 amps to battery only & full output from a classic but only 30A into the battery.
    Last edited: Sep 28, 2016
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  18. T. Riley

    T. Riley Monkey+++ Site Supporter++

  19. Cruisin Sloth

    Cruisin Sloth Special & Slow

    Last edited: Sep 28, 2016
    Ganado likes this.
  20. stg58

    stg58 Monkey+++ Founding Member

    Nice thought provoking thread.
    T. Riley likes this.
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