Need some solar help and advice

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


  1. oil pan 4

    oil pan 4 Monkey+++

    240v power at 10 amps will give you about 3 horsepower.
    You shut off pressure is about 130psi. If your surge tank builds up to 60psi.
    If you work 3.2 horsepower backwards at 130psi you get 42 gallons per minute.
    I know the pump isn't 100% efficient but something is not adding up.
    If it were 50% efficient that is still 20gpm.
    Most of these pumps should at least be 70% efficient.

    I went on lowes to look up the biggest submersible well pump I could find. It is a 1.5hp for wells up to 350 feet deep.
    Lets say you do 10gpm at 300 feet of static head (165 water column plus 60psi at tank level) that is only 3/4 of a horsepower.
    Lets say the pump is only 50% efficient so it needs 1.5 brake horsepower to run it (1,100 watts) it would only need about 4 to 5 amps at shutoff.
    Assuming you have this pump lets say you pump the well water into a regular non pressurized above ground tank (not into the pressurized tank) and only had to over come water column plus 10 feet (to the top of the above ground tank) then the pump would only need one horsepower if the pump was 50% efficient. 1 horsepower would need around 3 amps at shut off.
    You could always stick an amp clamp on it while its running and see how much power it draws.
     
    arleigh likes this.
  2. ghrit

    ghrit Bad company Administrator Founding Member

    Running draw isn't the critical data. The starting draw is of pretty significant interest for system sizing.
     
    arleigh likes this.
  3. T. Riley

    T. Riley Monkey+++ Site Supporter++

    @Cruisin Sloth - it is hard for me to follow you sometimes but I think you are saying to wire the batteries in series and replace the inverter with a 48v unit. What does this change as far as usable power is concerned? Not questioning the advice, just need to understand the logic. The house is wired only for AC. I am not worried about the air conditioning. I grew up in the south and did not have AC till I was in late teens.
     
  4. Cruisin Sloth

    Cruisin Sloth Special & Slow

    correct , I'm saying to wire the batteries in series and replace the inverter with a 48v unit. What does this change as far as usable power is concerned?
    How many KW's is the CC harvesting daily ?

    I had to look at mine CC midnite classic 150 harvests 15 -17 KW per day , so the power has got to go into batterys first & then into the internal grid tie & is being used by the AC / fridges / freezers etc.
    900 watts in a Grape solar panels ?
    See what your harvesting , it's under logs in the FM80
     
    Last edited: Jul 27, 2016
  5. T. Riley

    T. Riley Monkey+++ Site Supporter++

    @Cruisin Sloth - Will do so, I am wiring in the Midnight Solar MNPV6 you suggested tomorrow and resetting the angle of the panels. Should have a full day of sun on Friday and I will post the results on Saturday. Thanks for your help. I do not run my solar 24/7, only when I am here for a few days each week.
     
  6. Cruisin Sloth

    Cruisin Sloth Special & Slow

    OK , you can run your solar 24/7/365 when your comfortable with it . How I treat battery voltages is from SG of acid (battery make states it) and distilled water added to the cells , We need to add water !!! only on FLA , it keeps them stirred up ..

    Ya I now remember this system from way back .
    I see so many that I lose track .
    Remember to torque screws thrice 20 mins later & next day do all work once & proper.
    Makes ya feel better leaving it.
    900 watts in a Grape solar panels ?

    post the spec's if ya have them
     
    Last edited: Aug 16, 2016
  7. T. Riley

    T. Riley Monkey+++ Site Supporter++

    image.
     
  8. Cruisin Sloth

    Cruisin Sloth Special & Slow

    those are what the industry call 12Volt panels & are hard to find now or are not made as much .
    72 or 96 cell are the flavour of the year .
    Im 350W 48.3VOC 8.41A ISC 42.6 vmp 72cell .
    So the next is to see what your harvest is , YA get WAY more sun than I do .
    Im in the PNW of WA , but in Canada for sun reasons .

    See what ya harvest daily .
    Thats the way one can measure .
     
  9. arleigh

    arleigh Goophy monkey

    Remember too that one needs much more than what it takes to run things initially ,over time system requirements change as things deteriorate . I have been investing in back up panels for the future.
     
  10. Texas Monkey

    Texas Monkey Monkey

    Just a few items to consider
    9 amps at 240v equals about 180 amps at 12v
    And since you can only pull up to about 10% of a batteries amp hours at one time, this means if you have a 100 amp hour battery you can only pull about 10 amps at a time without dropping the volts so low that no device would run.
    This means your battery bank need to be at least 1800 amp hours to run that pump.
    Then you run into the LRA issue with electric motors, it may take 2 to 3 times the normal running amps to start the pump.
    I have a 5000 btu window air conditioner that says it pulls 4.5 amps to run, this means it takes 50 amps at 12v to run, my original 600ah batter bank could only run it for 10 minutes before the volts dropped below 11.5v which promptly shut down the inverter. My bank is bigger now.
    A general rule of thumb is to have 100 to 200 watts of solar per 100ah of battery, 100 in the south and 200 in the north, but if you only need to discharge your battery for an hour or less per day you might could probably use less than 100.
     
  11. Cruisin Sloth

    Cruisin Sloth Special & Slow

    There is NO general rule of thumb,, Over panel in some ares while others it's not needed , none two alike so NO general rule of thumb
     
  12. arleigh

    arleigh Goophy monkey

    One of the reasons I set up my switch panel so each component an be switched out and tested at random is because things change/age ,and a dip in power needs an explanation .
    My panels vary in age and watts and manufacture, so I track how each individual is doing. If I have a spare panel that performs better I replace the weaker one with it.
    If you don't know one from the other, and no way of proving them, the whole system is being drawn down, like one bad battery in your multi cell flash light, drawing them all down, and or cheating you out of service.
    Being able to isolate problems , saves a lot of frustration.
    Having proper fuses and diodes in place, protects the system from stuff your not there to observe and prevent to some degree.
    Some of us have critters to contend with and can be quite destructive , so even though all other precautions had been taken ,stuff still happens.
     
    Cruisin Sloth likes this.
  13. Cruisin Sloth

    Cruisin Sloth Special & Slow

    What i use !
    3 in series , 12 strings 36 panels , 350 watt CS 44.voc units = 12.6Kvdc

    12_Combiner.

    mnpv12-open-breakers.
     
  14. T. Riley

    T. Riley Monkey+++ Site Supporter++

    2 charge controllers? One battery bank?
     
  15. Texas Monkey

    Texas Monkey Monkey

    Most charge controllers play well with each other, just confirm that it says so in the manual,
    I have a 100 amp QO panel with three 15amp breakers, each breaker has two 150 watt panels hooked up for 24v,
    It is really nice to be able to shut them down individually or totally for battery maintenance.
     
  16. Cruisin Sloth

    Cruisin Sloth Special & Slow

    3 units in follow me , Classic & 2 lites in follow me . Only one MNGP & monitored controlled . 300Amps DC needs 4-O or 350 class cable .
    1 set of cells at 48Vdc , MNSpecial I'll jump to 96Vdc cell pack .

    ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
    @Texas Monkey
    your 15amp breakers are to large for the twin in series panels of IMP 7 amp max , more like 10 amp MAX , Id be on 8 amp ones .
    Same wiring , but way less amps . 15 Amp will not trip the way it is to protect .
    Edit update (since info was posted) 8.4Adc in the best day .
    For myself one 10amp breaker per string .

    Sloth
     
    Last edited: Sep 13, 2016
  17. Texas Monkey

    Texas Monkey Monkey

    Per the NEC you breaker solar at 1.25 times the Isc which in my case is 8.76A x 1.25 = 10.95 amps,
    then you round up not down to find a breaker.

    NEC Rules on Alternative Energy Systems — Part 1

    Cruisin Sloth,
    Perhaps you should ease up on your declarative statements,
    I would some wiggle room and advise others to seek a second opinion, as well as give advise on how not to kill yourself or burn your home down, errors of amps and volts kill people, just like errors of omission.
    The NEC code error above is not likely to kill anyone but it might lead to some irritating breaker throws.
    Liability can go both to the author and web site.
    My past "rule of thumb" as well as others I use a way to double check my math, god knows I make math errors all the time.

    I have DM solar 158 watt panels,
    * 36pcs of 6" mono-crystalline solar cells -
    * Cell Efficiency: 18%
    * Max Voltage: 1000V
    * Pmax: 158W
    * Vmp: 18.9V
    * Imp: 8.47A
    * Voc: 22.7V
    * Isc: 8.76A
    * Size: 58.27"x26.58"x1.38"
    * Weight: 26.4lbs

    NEC Rules on Alternative Energy Systems — Part 1

    Per the NEC you breaker solar at 1.25 times the Isc which in my case is 8.76A x 1.25 = 10.95 amps,
    then you round up not down to find a breaker.








    .
     
  18. Cruisin Sloth

    Cruisin Sloth Special & Slow

    OK,
    I was only , but whatever !
    My MATH OUTCOME is different than yours.
    I know them rule's and they were just updated 2015NEC , I have the book in PDF format with the licence.
    How many strings of 2 panels in Parallel ?

    But then again , were NOT protecting VOC ...with the breakers ,
    T.riley knows why & how the breaker math IS figured.

    EDIT ADD :
    I see YOU JOINED Friday & 3 post's & now my thumbs are in question .
    We have many RE type folks here.

    SLOTH
     
    Last edited: Sep 14, 2016
    Ganado likes this.
  19. Cruisin Sloth

    Cruisin Sloth Special & Slow

    """"
    Sizing overcurrent protection devices (OCPDs)
    You must size the circuit conductors to carry the larger of:

    • 125% of the currents as calculated in 690.8(A) before the application of conductor adjustment and correction of 310.15 [690.8(B)(2)(a)].
    • The maximum current calculated in 690.8(A) after the application of conductor adjustment and correction of 310.15 [690.8(B)(2)(b)].
    You must size the conductor overcurrent protection to the conductor ampacity after the application of conductor adjustment and correction of 310.15 per 240.4(B), 240.4(C), and 240.4(D).""""
    Wire size @ the 125% over breaker , NOT BREAKER LIMITS
     
  20. Texas Monkey

    Texas Monkey Monkey

    Yep, I joined THIS board on friday, but it does not change the math,
    My reading of the full paragraph below shows that both the wire size and breaker capacity are multiplied 125%
    I did not question your previous posts, you questioned my breaker size.


    NEC Rules on Alternative Energy Systems — Part 1
    Sizing overcurrent protection devices (OCPDs)

    Size OCPDs to carry not less than 125% of the current as calculated in 690.8(A) [690.8(B)(1)(a)], and:
    • Apply the terminal temperature limits of 110.14(C) [690.8(B)(1)(b)].
    • If operating above 40˚C, use the manufacturer’s temperature correction factors to adjust the ampacity rating of the OCPD [690.8(B)(1)(c)].
    • Use settings or ratings permitted for OCPDs by 240.4(B), (C), and (D) [690.8(B)(1)(d)]
    For OCPDs 800A or less, you can use the next higher standard rating of an OCPD listed in 240.6 (above the ampacity of the ungrounded conductors being protected) — but only if you satisfy all three conditions listed in 240.4(B).
    You must size the circuit conductors to carry the larger of:
    • 125% of the currents as calculated in 690.8(A) before the application of conductor adjustment and correction of 310.15 [690.8(B)(2)(a)].
    • The maximum current calculated in 690.8(A) after the application of conductor adjustment and correction of 310.15 [690.8(B)(2)(b)].
    You must size the conductor overcurrent protection to the conductor ampacity after the application of conductor adjustment and correction of 310.15 per 240.4(B), 240.4(C), and 240.4(D).
     
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