Safety of High Voltage portable panels?

hello all,

I'm wanting cable runs up to 20Meters or more  for my portable folding panels and no thicker than 10GA wire. And using anderson plugs as they are quick connect, I normally just hot plug them into charge controller input.

I currently have 3X 300watt 22voc folding panels wired in parallel to my victron mppt. Apon setting up panels I normally just plug the cable ends into panel & into CC. There is a 50amp toggle DC switch right before my CC for convenience. Although hot plugging anderson plugs with the switch ON doesn't seem to hurt them at low 17 volts.


I'm wanting to re-wire each panel's wiring to series so they each would be 66voc total. How dangerous is this with hot plugging anderson plugs? I read about arcing when doing this but not sure.
What fuses do I use? All auto style fuses I use like midi & blade are limited to just 32volts.

There don't look to be any DC toggle switches for this voltage, so what else should I use as a switch?
Perhaps MC4 connectors are they way to go on the panel's end where there will be no hotplugging, as anderson plugs are open & in the wet one may get an electric shock standing next to panel?


What else is dangerous?

thanks

Comments

  • mcgivormcgivor Solar Expert Posts: 2,905 ✭✭✭✭✭
    edited November 2018 #2
    Connecting/disconnecting any type of connector under load, particularly DC is not recommended due to arcing, while it may not cause immediate damage the aggregate over time will likely cause high resistance. Providing a means of disconnect in the form of a DC circuit breaker, here's an example https://www.amazon.com/Low-voltage-Miniature-Circuit-Breaker-Panels/dp/B07351F2J1?ref_=fsclp_pl_dp_10
    will not only provide a switching function but also serve as overcurrent protection. Best not to use automotive type components as they generally are not intended to carry close to rated currents for extended periods of time. Anderson connectors are perhaps useful in portable applications but are not commonly used, that being said the installation of a circuit breaker would aleivate the entire issue. When panels are wired in series if one panel is shaded, the whole strings output collapses, so if you choose to ignore the recomendations at least throw a blanket over at least one panel in series, or all if in parallel.

    Are the voltages in the case of a few panels in series dangerous?  Perhaps if one has a bad heart or a pacemaker,  otherwise just a little surprise to the average person. High voltage has no clear definition, it depends on local code interpretation, but anything lower than 600V is generally  considered low voltage, although you may not think so when it grabs ahold of you, DC in particular because it doesn't let go every 1/60 or 1/50 th of a second depending on frequency. 

    Always work safe, it really doesn't take that much to take precautions.
    1500W, 6× Schutten 250W Poly panels , Schneider MPPT 60 150 CC, Schneider SW 2524 inverter, 400Ah LFP 24V nominal battery bank 
    Second system 1890W  3 × 300W No name brand poly, 3×330 Sunsolar Poly panels, Morningstar TS 60 PWM controller, no name 2000W inverter 400Ah FLA 24V nominal used for water pumping and day time air conditioning.  
    5Kw Yanmar clone single cylinder air cooled diesel generator for rare emergency charging and welding.
  • mike95490mike95490 Solar Expert Posts: 8,288 ✭✭✭✭✭
    edited November 2018 #3
    Neither Anderson or MC4 should be connected / disconnected under load.  You need a dc circuit breaker to use as a switch.
     Midnight Solar sells switch rated DC breakers for 150V for about $20.  Then you need to mount it to a flat panel with a slot and screw holes,  it has bolt & nut terminals for Ring Lugs.
    My link goes to panel mount breaker, the earlier link requires a box with DIN rails for mounting and has bare wire clamps.

    Powerfab top of pole PV mount | Listeroid 6/1 w/st5 gen head | XW6048 inverter/chgr | Iota 48V/15A charger | Morningstar 60A MPPT | 48V, 800A NiFe Battery (in series)| 15, Evergreen 205w "12V" PV array on pole | Midnight ePanel | Grundfos 10 SO5-9 with 3 wire Franklin Electric motor (1/2hp 240V 1ph ) on a timer for 3 hr noontime run - Runs off PV ||
    || Midnight Classic 200 | 10, Evergreen 200w in a 160VOC array ||
    || VEC1093 12V Charger | Maha C401 aa/aaa Charger | SureSine | Sunsaver MPPT 15A

    solar: http://tinyurl.com/LMR-Solar
    gen: http://tinyurl.com/LMR-Lister ,

  • PhotowhitPhotowhit Solar Expert Posts: 4,912 ✭✭✭✭
    I currently have 3X 300watt 22voc folding panels wired in parallel to my victron mppt. 
    I would guess you have KickAss panels? which appear to be 3 - 36 cell panels in parallel?

    KICKASS 300W 12V Portable Camping Folding Solar Panel  PWM Solar Controller
    In stead of;
    I'm wanting to re-wire each panel's wiring to series so they each would be 66voc total.
    You might just run the 3 - 300 watt in series to give you 900 watts at higher voltage rather than running them in parallel.

    Midnite has din rail breakers and panel mount breakers that would meet your criteria (I believe), I would use the panel mount and a utility/project box for a potable unit.
    Home system 4000 watt (Evergreen) array standing, with 2 Midnite Classic Lites,  Midnite E-panel, Prosine 1800 and Exeltech 1100, 660 ah 24v ForkLift battery. Off grid for @16 of last 17 years. Assorted other systems, and to many panels in the closet to not do more...lol
  • MontyYoungMontyYoung Registered Users Posts: 3
    mcgivor said:
    When panels are wired in series if one panel is shaded, the whole strings output collapses, so if you choose to ignore the recomendations at least throw a blanket over at least one panel in series, or all if in parallel.

    Thanks, even standard portable folding panels are heavily affected by shade so I don't see the point in worrying about series. Cheers.
  • MontyYoungMontyYoung Registered Users Posts: 3
    mike95490 said:
    Neither Anderson or MC4 should be connected / disconnected under load.
    Even at 17volts? Everyone seems to do it with 12V stuff with no issues. But I will try to keep it to a minimum.
  • BB.BB. Super Moderators, Administrators Posts: 29,229 admin
    MC4 connectors are designed with thin gold and high contact pressures. They have a limited design life (something like 100 plug/unplug cycles). And they are easily damaged by arcing (erodes the the contacts, perhaps damage that causes faster wear).

    12 volts is roughly the point at which arcs can be "sustained". Below 12 volts, it is very difficult for any arcs to be sustained. 24 volts--very nice arc welder.

    There is also just the natural issue that DC current is more difficult to "break" vs AC current:



    Are you going to have big issues with unplugging a "12 volt" 100 Watt (18 volts at 5.5 amps)--I don't think anyone is going to get hurt.

    However, Anderson does tell folks to not disconnect under load for longer contact life:

    http://www.andersonpower.com/_global-assets/downloads/pdf/app_pm.pdf

    B. Check contact surfaces for signs of “pitting” caused by dirt or disengaging connectors under load. One badly pitted contact, particularly in a connector attached to a battery charger, can lead to pitting on surfaces of other contacts. If not corrected, this can result in an epidemic of bad connectors throughout a fleet of electric vehicles and in chargers and batteries. 

    C. Check to see if batteries are being disconnected while the charger is still on. This causes the contacts to arc at the tips, resulting with progressive pitting and silver removal from tip to crown. If this practice is occurring, discontinue it now to avoid major repairs in the future.

    -Bill
    Near San Francisco California: 3.5kWatt Grid Tied Solar power system+small backup genset
  • MontyYoungMontyYoung Registered Users Posts: 3
    Photowhit said:
    I currently have 3X 300watt 22voc folding panels wired in parallel to my victron mppt. 
    I would guess you have KickAss panels? which appear to be 3 - 36 cell panels in parallel?

    KICKASS 300W 12V Portable Camping Folding Solar Panel  PWM Solar Controller
    In stead of;
    I'm wanting to re-wire each panel's wiring to series so they each would be 66voc total.
    You might just run the 3 - 300 watt in series to give you 900 watts at higher voltage rather than running them in parallel.

    Midnite has din rail breakers and panel mount breakers that would meet your criteria (I believe), I would use the panel mount and a utility/project box for a potable unit.
    Yes those are the panels.
    I don't think I can run the 3 panels in series as they are going to be possibly at different locations & I see it as more work to wire up & connect.
    I was thinking of mounting the DC circuit breaker on the under face of the panel. Not sure if it's a good idea?
  • EstragonEstragon Registered Users Posts: 3,721 ✭✭✭✭✭
    In a waterproof box with drip loops maybe, but probably more convenient near the controller.
    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
Sign In or Register to comment.