Upgraded, new question..

hillside
hillside Registered Users Posts: 148 ✭✭
In June I bought new batteries for my system (with too much capacity) and was advised here to look at adding more panel wattage. So was able to add 3 more panels to the existing system which I wired in series. The new panels (slightly used) are 2 Hanwha 235W and one Sonali 230W. I added a Renogy 40A MPPT CC to the existing battery bank.
I'm not sure if my specs. will show as I had to reset password here.
So, the original set-up is 4- 235W panels in series,
4 Deka 6V. 370AH batteries, 24Volt system, an SRNE 40A MPPT CC, with a Cotek 3000 Watt pure sine inverter.
This set-up has been working fine but adding more wattage was the advice..it had been showing approx. 65volts at the CC from the panels
So, now, the 3 new panels are showing a voltage reading in peak sun of 90-92 Volts while the other CC shows 65V.
When clouds appear both CC's show similar voltage at about 37..all wiring is 10G.
What would explain the big difference?
Is my first original 4 panel system not producing correctly?


8- 235Watt panels, 2 strings in series/parallel, 4L16 Deka 6Volt, 370AH FLA. batteries, 3000W Cotek pure sine inverter, SRNE ML2440 40Amp Controller &  40 Amp Renogy controller, 24 Volt system.
5 stand alone PV arrays; 12V gate opener, 24V Dankoff rain water pumping system, 12V Shurflo rain water garden pumping, 12V bathroom LED lighting and fan.
4- 450 Watt panels with 4 L16 6 volt batts./ 2-Renogy Tracer 40 Amp controllers/ Xantrex 1800W PSW Inverter.
Honda EU3000W generator for backup.

Comments

  • hillside
    hillside Registered Users Posts: 148 ✭✭
    And at the battery connections both readings are near identical @ 26.2, 26.3..for what that's worth.
    8- 235Watt panels, 2 strings in series/parallel, 4L16 Deka 6Volt, 370AH FLA. batteries, 3000W Cotek pure sine inverter, SRNE ML2440 40Amp Controller &  40 Amp Renogy controller, 24 Volt system.
    5 stand alone PV arrays; 12V gate opener, 24V Dankoff rain water pumping system, 12V Shurflo rain water garden pumping, 12V bathroom LED lighting and fan.
    4- 450 Watt panels with 4 L16 6 volt batts./ 2-Renogy Tracer 40 Amp controllers/ Xantrex 1800W PSW Inverter.
    Honda EU3000W generator for backup.
  • Estragon
    Estragon Registered Users Posts: 4,496 ✭✭✭✭✭
    My guess is the string of 4 x 235w original panels aren't a single string, but are two seies strings of two panels each in parallel.

     This would give you a Vmp of ~30 x 2 = 60v.  Assuming a Voc of ~40v, 4 in series would overvoltage (~160v) many controllers.  The spec for the controller in your sig says max Vmp of 75v.  Usually max string voltage spec is Voc, so I'm not sure if it really is Vmp.    

    The new string of three, with Vmp of ~90v sounds about right.  Renogy has various models, but at least some controllers have a max Voc of 100v, so you may want to check actual panel Voc spec, adjusted up for record low temp at your location, to be sure it won't get overvoltaged.
    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
  • hillside
    hillside Registered Users Posts: 148 ✭✭
    This is the diagram for the 4 panels:
    Image result for Solar panels in series and parallel

    8- 235Watt panels, 2 strings in series/parallel, 4L16 Deka 6Volt, 370AH FLA. batteries, 3000W Cotek pure sine inverter, SRNE ML2440 40Amp Controller &  40 Amp Renogy controller, 24 Volt system.
    5 stand alone PV arrays; 12V gate opener, 24V Dankoff rain water pumping system, 12V Shurflo rain water garden pumping, 12V bathroom LED lighting and fan.
    4- 450 Watt panels with 4 L16 6 volt batts./ 2-Renogy Tracer 40 Amp controllers/ Xantrex 1800W PSW Inverter.
    Honda EU3000W generator for backup.
  • hillside
    hillside Registered Users Posts: 148 ✭✭
    forgot to ask, would  this diagram above be correct to show 65Volts at peak sun? Thanks for the help.
    8- 235Watt panels, 2 strings in series/parallel, 4L16 Deka 6Volt, 370AH FLA. batteries, 3000W Cotek pure sine inverter, SRNE ML2440 40Amp Controller &  40 Amp Renogy controller, 24 Volt system.
    5 stand alone PV arrays; 12V gate opener, 24V Dankoff rain water pumping system, 12V Shurflo rain water garden pumping, 12V bathroom LED lighting and fan.
    4- 450 Watt panels with 4 L16 6 volt batts./ 2-Renogy Tracer 40 Amp controllers/ Xantrex 1800W PSW Inverter.
    Honda EU3000W generator for backup.
  • hillside
    hillside Registered Users Posts: 148 ✭✭
    Record ow temperatures in my area are about 67 degrees in January..(central Caribbean)
    Days average 77-90 year round.
    The Renogy CC is the 2440 model.
    8- 235Watt panels, 2 strings in series/parallel, 4L16 Deka 6Volt, 370AH FLA. batteries, 3000W Cotek pure sine inverter, SRNE ML2440 40Amp Controller &  40 Amp Renogy controller, 24 Volt system.
    5 stand alone PV arrays; 12V gate opener, 24V Dankoff rain water pumping system, 12V Shurflo rain water garden pumping, 12V bathroom LED lighting and fan.
    4- 450 Watt panels with 4 L16 6 volt batts./ 2-Renogy Tracer 40 Amp controllers/ Xantrex 1800W PSW Inverter.
    Honda EU3000W generator for backup.
  • hillside
    hillside Registered Users Posts: 148 ✭✭
    Correction, the Renogy with the 3 panels is Tracer 4210, still 40A.
    (don't post when tired) :)
    8- 235Watt panels, 2 strings in series/parallel, 4L16 Deka 6Volt, 370AH FLA. batteries, 3000W Cotek pure sine inverter, SRNE ML2440 40Amp Controller &  40 Amp Renogy controller, 24 Volt system.
    5 stand alone PV arrays; 12V gate opener, 24V Dankoff rain water pumping system, 12V Shurflo rain water garden pumping, 12V bathroom LED lighting and fan.
    4- 450 Watt panels with 4 L16 6 volt batts./ 2-Renogy Tracer 40 Amp controllers/ Xantrex 1800W PSW Inverter.
    Honda EU3000W generator for backup.
  • Estragon
    Estragon Registered Users Posts: 4,496 ✭✭✭✭✭
    The diagram is 2S2P so yes, 65v is about right.

    Tracer 4210 appears to be a generic chinese controller.  I didn't see it listed on Renogy website but the generic seems to be 92 or 100Voc max.  You may be ok in your warm climate, but likely close to max.  

    What is the Voc spec for the new panels?
    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
  • hillside
    hillside Registered Users Posts: 148 ✭✭
    36.8 on two of them and the third, a Sonali 60 cell (all are 60)has the label faded away from rain/heat and is illegible.
    You're right that the Renogy input voltage is 100V..
    (great--I have been trying to get away from all things Chinese made...this was an ebay purchase, live and learn. At least my inverter is Taiwan made. :)
    Just checked voltage again in peak sun, 92V on the 3 panels and 65 on the 4 2S2P's.

    Should I use a smaller fuse from the 3 panels to the Renogy CC?
    Right now I'm way over with a 30Amp. I did a check yesterday with the multi meter and it showed 5 Amps at 92volts. Not sure if it was a valid check as I haven't used that amp test mode before..
    Thanks for the help.
    8- 235Watt panels, 2 strings in series/parallel, 4L16 Deka 6Volt, 370AH FLA. batteries, 3000W Cotek pure sine inverter, SRNE ML2440 40Amp Controller &  40 Amp Renogy controller, 24 Volt system.
    5 stand alone PV arrays; 12V gate opener, 24V Dankoff rain water pumping system, 12V Shurflo rain water garden pumping, 12V bathroom LED lighting and fan.
    4- 450 Watt panels with 4 L16 6 volt batts./ 2-Renogy Tracer 40 Amp controllers/ Xantrex 1800W PSW Inverter.
    Honda EU3000W generator for backup.
  • Estragon
    Estragon Registered Users Posts: 4,496 ✭✭✭✭✭
    With just one or two strings of panels to a controller, you don't really need string fuses at all.  If used, the size is per panel spec (often 10-15a).  You do need fuses/breakers on the controller DC output (battery) though.

    5a could be about right.  You likely have a marine haze layer which would reduce insolation a bit, and the controller may be into absorb (when current tapers off as the SOC rises).

    Peak string voltage tends to happen, for example, early in the morning when the panels are coolest and there's just enough light for voltage to reach max Voc.  Once the sun hits the panels, they get warmed and voltage drops.

    I'm in a much colder climate, and my strings of 3 x 250w panels range from ~90v to ~120v.  My controllers take >150v though, so not a problem.  IMHO, 92v with warm panels is cutting it a bit close with a 100v max controller.  Spec Voc of 36.8 (at 25°C?) x 3 = 110.4v.  With a record low ~10°F lower than that (so higher Voc), an overvoltage seems a real risk at some point.

    I would try to get another panel with about the same spec as the new three, and do another 2S2P array.  In the meantime, I'd disconnect one panel from the string, leaving just two in series.  You might get lucky for a while, but I know I'm not that lucky.  The controller may not be ruined at 100.00001v, but it will likely at least log the overvoltage and void warranty, and may suffer damage that turns up later.
    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
  • hillside
    hillside Registered Users Posts: 148 ✭✭
    thanks for the information, much appreciated.
    I've noticed the voltage drop noticeably when temps. go up.
    I'll look for another panel and will be watching voltage carefully but will probably do as you say and disconnect one panel. Adding a 4th is the best idea.

    8- 235Watt panels, 2 strings in series/parallel, 4L16 Deka 6Volt, 370AH FLA. batteries, 3000W Cotek pure sine inverter, SRNE ML2440 40Amp Controller &  40 Amp Renogy controller, 24 Volt system.
    5 stand alone PV arrays; 12V gate opener, 24V Dankoff rain water pumping system, 12V Shurflo rain water garden pumping, 12V bathroom LED lighting and fan.
    4- 450 Watt panels with 4 L16 6 volt batts./ 2-Renogy Tracer 40 Amp controllers/ Xantrex 1800W PSW Inverter.
    Honda EU3000W generator for backup.
  • hillside
    hillside Registered Users Posts: 148 ✭✭
    Yesterday's highest reading was 98Volts. Yikes! :)
    8- 235Watt panels, 2 strings in series/parallel, 4L16 Deka 6Volt, 370AH FLA. batteries, 3000W Cotek pure sine inverter, SRNE ML2440 40Amp Controller &  40 Amp Renogy controller, 24 Volt system.
    5 stand alone PV arrays; 12V gate opener, 24V Dankoff rain water pumping system, 12V Shurflo rain water garden pumping, 12V bathroom LED lighting and fan.
    4- 450 Watt panels with 4 L16 6 volt batts./ 2-Renogy Tracer 40 Amp controllers/ Xantrex 1800W PSW Inverter.
    Honda EU3000W generator for backup.
  • Estragon
    Estragon Registered Users Posts: 4,496 ✭✭✭✭✭
    I'd be unplugging the 3rd panel real soon now.

    Turning the controller off first, and maybe throwing a tarp over the string might be wise  ;)
    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
  • hillside
    hillside Registered Users Posts: 148 ✭✭
    Will do. I always cover them when doing this stuff. Thanks again.
    8- 235Watt panels, 2 strings in series/parallel, 4L16 Deka 6Volt, 370AH FLA. batteries, 3000W Cotek pure sine inverter, SRNE ML2440 40Amp Controller &  40 Amp Renogy controller, 24 Volt system.
    5 stand alone PV arrays; 12V gate opener, 24V Dankoff rain water pumping system, 12V Shurflo rain water garden pumping, 12V bathroom LED lighting and fan.
    4- 450 Watt panels with 4 L16 6 volt batts./ 2-Renogy Tracer 40 Amp controllers/ Xantrex 1800W PSW Inverter.
    Honda EU3000W generator for backup.
  • hillside
    hillside Registered Users Posts: 148 ✭✭
    Finally, one more question..well, two. I've not changed anything yet and voltage has not gone over that one time reading of 98V, mostly staying in the 80-90V range.
    Is it possible that because I'm in a tropical climate and the sun doesn't hit the panels until about 10AM, that the heat will reduce the panel voltage before it can reach damaging levels?
    (Estragon suggested finding another panel but it's near impossible as most retailers now carry 300W+ and finding one in the 235-250 range (used) won't happen)

    Question 2: If panel voltage goes over 100V will it damage the solar panels or just the charge controller? I'd rather buy another controller than try to find panels.
    I'll keep looking for another panel to add and wire in 2S2P in the meantime but I'm also counting on frequent cloud cover to keep things within limits. I kind of like living on the edge :)
    Thanks and Happy Thanksgiving to all.
    Seen on a bumper sticker: "what are you thankful for?"


    8- 235Watt panels, 2 strings in series/parallel, 4L16 Deka 6Volt, 370AH FLA. batteries, 3000W Cotek pure sine inverter, SRNE ML2440 40Amp Controller &  40 Amp Renogy controller, 24 Volt system.
    5 stand alone PV arrays; 12V gate opener, 24V Dankoff rain water pumping system, 12V Shurflo rain water garden pumping, 12V bathroom LED lighting and fan.
    4- 450 Watt panels with 4 L16 6 volt batts./ 2-Renogy Tracer 40 Amp controllers/ Xantrex 1800W PSW Inverter.
    Honda EU3000W generator for backup.
  • Estragon
    Estragon Registered Users Posts: 4,496 ✭✭✭✭✭
    Check the specs on available panels.  I'd consider about a 10% higher spec "close enough", (eg a ~37Voc and 40Voc).

    The higher voltage shouldn't hurt the panels.  Most are rated to several 100s of volts.  600v arrays aren't unusual.

    A little above 100v may not hurt the controller right away either (other than logging the overvoltage event).  The rating should be conservative, but especially with devices without (legit) ETL ratings, it's hard to be sure to what extent.

    The sun doesn't have to hit panels directly to get near max Voc.  Warm ambient temps will limit the rise though.
    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
  • hillside
    hillside Registered Users Posts: 148 ✭✭
    Thanks for that information- I'll keep looking at panels.
    8- 235Watt panels, 2 strings in series/parallel, 4L16 Deka 6Volt, 370AH FLA. batteries, 3000W Cotek pure sine inverter, SRNE ML2440 40Amp Controller &  40 Amp Renogy controller, 24 Volt system.
    5 stand alone PV arrays; 12V gate opener, 24V Dankoff rain water pumping system, 12V Shurflo rain water garden pumping, 12V bathroom LED lighting and fan.
    4- 450 Watt panels with 4 L16 6 volt batts./ 2-Renogy Tracer 40 Amp controllers/ Xantrex 1800W PSW Inverter.
    Honda EU3000W generator for backup.
  • hillside
    hillside Registered Users Posts: 148 ✭✭
    Estragon, you were correct! Panel voltage went over 100Volts today and that Renogy controller shut itself down until the voltage dropped to safe levels. Then it turned itself back on. And all is well, for now anyway.
    Searching for another panel now and go 2 series/2 parallel!
    8- 235Watt panels, 2 strings in series/parallel, 4L16 Deka 6Volt, 370AH FLA. batteries, 3000W Cotek pure sine inverter, SRNE ML2440 40Amp Controller &  40 Amp Renogy controller, 24 Volt system.
    5 stand alone PV arrays; 12V gate opener, 24V Dankoff rain water pumping system, 12V Shurflo rain water garden pumping, 12V bathroom LED lighting and fan.
    4- 450 Watt panels with 4 L16 6 volt batts./ 2-Renogy Tracer 40 Amp controllers/ Xantrex 1800W PSW Inverter.
    Honda EU3000W generator for backup.
  • hillside
    hillside Registered Users Posts: 148 ✭✭
    (That was written in the owner's manual--that it would shut itself off and restart when safe.)
    8- 235Watt panels, 2 strings in series/parallel, 4L16 Deka 6Volt, 370AH FLA. batteries, 3000W Cotek pure sine inverter, SRNE ML2440 40Amp Controller &  40 Amp Renogy controller, 24 Volt system.
    5 stand alone PV arrays; 12V gate opener, 24V Dankoff rain water pumping system, 12V Shurflo rain water garden pumping, 12V bathroom LED lighting and fan.
    4- 450 Watt panels with 4 L16 6 volt batts./ 2-Renogy Tracer 40 Amp controllers/ Xantrex 1800W PSW Inverter.
    Honda EU3000W generator for backup.