Can panels be installed without being hooked up yet?

showmeshowme Registered Users Posts: 85 ✭✭
in Solar Beginners Corner #1

I'm finally getting started with our solar project, and I'm about ready to put up our modules. I'll have 2 top of pole mounts with 12 modules each (LG Neon2 320w). I've got the 8" poles set, have one MT Solar rack started, and I'm setting the rails today. I want to get the panels mounted and the rack up and secure before bad weather hits. I still have to put up the building to temporarily store our power equipment until we build our house there this spring.

My question is, how do I wire (or not) my array so that it will not damage them until I get the rest of the system up and running? I'm not sure if I need to leave the wires disconnected, connect each panel's +/- wires, or what? Do I need to cover them with tarps until ready?

Leaving them till later is not an option. Thanks, Lee

"Knowing is not enough, we must apply. Willing is not enough, we must do."   Goethe

NOS Trace Xantrex power panel, (3) Trace Xantrex SW5548's (2 NOS in boxes, one used), Xantrex DC/disconnect, AC disconnect/conversion, Xantrex T240 Auto transformer, (3) C40 PWM charge controllers, (2 NOS, one used)  8k LG Neon 320w, (8)Evergreen  Solar 120w (960w)  , Bergey XL.1 1.5k genny, AirX 400 genny, 48v Interstate Workman batts (frozen/toast), (2) MT Solar Top of Pole 12's, (2) Midnite Solar MSPV 4 combiner boxes, (2) Midnite Solar Classic 150's and one nice Ozark hilltop to set them all.


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  • 706jim706jim Solar Expert Posts: 500 ✭✭✭✭
    #2
    Wire them up now but be sure to cap off the wire ends so that you don't accidently shock yourself or anybody else.
    Island cottage solar system with 2500 watts of panels, 1kw facing southeast 1.3kw facing southwest 170watt ancient Arco's facing south. All panels in parallel for a 24 volt system. Trace DR1524 MSW inverter, Outback Flexmax 80 MPPT charge controller 8 Trojan L16's. Insignia 11.5 cubic foot electric fridge. My 29th year.
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  • Wheelman55Wheelman55 Registered Users Posts: 209 ✭✭✭
    #3
    And do the final wiring in the evening or early morning when there is no sun on the panels. 
    Off-Grid in Terlingua, TX
    5,000 watt array - 14 CS 370 watt modules. HZLA horizontal tracker. Schneider: XW6048NA+, Mini PDP, MPPT 80-600, SCP. 390ah LiFeP04 battery bank - 3 Discover AES 42-48-6650 48 volt 130ah LiFePO4 batteries
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  • wellbuiltwellbuilt Solar Expert Posts: 763 ✭✭✭✭
    #4
    ^^^^^^
     I did this , we just let the bank sit until every thing was set up .
     I finished the array at nite with head lights . 
     I have a breaker panel now so no problem .
    Out back  flex power one  with out back 3648 inverter fm80 charge controler  flex net  mate 16 gc215 battery’s 4425 Watts solar .
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  • mike95490mike95490 Solar Expert Posts: 9,583 ✭✭✭✭✭
    #5
    I'd wire the panels into their disconnect box, and then , leave it in the Disconnect position.
    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 ,

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  • PhotowhitPhotowhit Solar Expert Posts: 5,991 ✭✭✭✭✭
    #6
    NO REASON TO EVER WORK IN THE DARK!!!

    Properly wired the panels should be wired to an open breaker or an empty fuse. 
    Home system 4000 watt (Evergreen) array standing, with 2 Midnite Classic Lites,  Midnite E-panel, Magnum MS4024, Prosine 1800(now backup) and Exeltech 1100(former backup...lol), 660 ah 24v Forklift battery(now 10 years old). Off grid for 20 years (if I include 8 months on a bicycle).
    - Assorted other systems, pieces and to many panels in the closet to not do more projects.
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  • showmeshowme Registered Users Posts: 85 ✭✭
    #7
    Thanks for the replies, folks. I found this interesting post on a physics forum https://physics.stackexchange.com/questions/71434/where-does-electricity-go-from-a-solar-panel-that-is-not-plugged-in-to-anything, that is pretty interesting. Seems plugging the two leads together is the option I'm going with right now. Keep the plugs from corroding and zeroing out the current. I'd love to wire it up now, but I'm using MT Solar racks that use a chain fall to lift it into place. Until I get the rack up and attached where I want it, I can't jump the chain fall and lifting rig to the second pipe to get it started. The bad part is, everything is at shoulder level right now. Much better than working off a ladder. I'll report back with an update.

    "Knowing is not enough, we must apply. Willing is not enough, we must do."   Goethe

    NOS Trace Xantrex power panel, (3) Trace Xantrex SW5548's (2 NOS in boxes, one used), Xantrex DC/disconnect, AC disconnect/conversion, Xantrex T240 Auto transformer, (3) C40 PWM charge controllers, (2 NOS, one used)  8k LG Neon 320w, (8)Evergreen  Solar 120w (960w)  , Bergey XL.1 1.5k genny, AirX 400 genny, 48v Interstate Workman batts (frozen/toast), (2) MT Solar Top of Pole 12's, (2) Midnite Solar MSPV 4 combiner boxes, (2) Midnite Solar Classic 150's and one nice Ozark hilltop to set them all.


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  • BB.BB. Super Moderators, Administrators Posts: 33,140 admin
    #8
    I am not sure I agree with the link on what happens with a "disconnected" solar panel...

    The voltage generated by a cell is correct--Around 0.5 volts Vmp (voltage maximum power) per cell when connected to a load... But when not connected, the panel generates around 0.7 volts Voc (voltage open circuit). The reason is the "diode junction" goes into "conduction" to "clamp" the voltage at 0.7 volts. So there is current flow and heat developed (power=voltage*current -- Which is true even for a diode).

    So, an "unconnected" solar panel will "run hotter" if disconnected (energy stays "in-panel") vs a panel connected to a load (electrical energy is "transported" "off-panel").

    Now a typical residential solar panel is something like 12-18% efficient--So that "extra heat" generated in-panel will not raise the panel temperature much higher than a load connected panel (12-18% "more energy" as heat in panel).

    There are solar panels that must be connected to loads/short circuited if left in the sun. These panels (as far as I know) are only used in large commercial solar farms (if they are even still produced these days?). In this case, the panels will have "issues" if left in sun for more than a week or so in full sun "unconnected" (some sort of thin film panel as I recall).

    Note that the standard MC4 solar connectors are not rated for a large number of make/break cycles (a few connect/disconnect cycles are not going to be an issue). And disconnecting the connectors under current flow (loads, shorted panel under sun)--The connectors can arc and damage the mating surfaces (very thin gold layer over base metal)... So I would not suggest shorting/opening MC4 connectors on a panel under sunlight.

    -Bill
    Near San Francisco California: 3.5kWatt Grid Tied Solar power system+small backup genset
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