Putting the pieces together

bfitzgerald
bfitzgerald Registered Users Posts: 26 ✭✭
in PV Installers Forum - NEC, Wiring, Installation #1
Hi,

This is my first post to this forum although I have been reading through it for some time without registering. I am amazed at the support provided by the experts and the moderators. I am not new to solar power and have been using it at my remote cabin since a 90 watt panel sold for $1300. I am in the process of upgrading and have aquired most of the big pieces:
6 - 200 watt CS panels
1 - Xantrex SCC MPPT charge controller
1 - Xantrex XW 4024
1 - Xantrex control panel
12 - 2v batteries (used) rated at 1010 amp hours at the 8 hour rate.

The panels will be roof mounted on a "power shed" with the batteries, inverter and charge controller. Distances from charge controller, inverter and the batteries will be less than 8 feet. I will need 2 panel strings to keep the voltage safely under 150v in our very cold weather.

I have looked at both the Xantrex and Midnite Solar distribution panels and think that they are a bit expensive - especially the Xantrex. This is where I am asking for advice and I guess a list of what people would recommend to complete this installation. One other thing that I would ask about is lightning protection - I did lose most of my system including the charge controller, lots of lights, and stereo to lightning. I'd like to try to protect against this in the future!

I look forward to any responses and thank you.

Brian
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Comments

  • niel
    niel Solar Expert Posts: 10,300 ✭✭✭✭
    #2
    Re: Putting the pieces together

    if you have the ability you could make something using a buss like for example http://www.lowes.com/pd_67694-296-PK4GTACP_4294821909_4294937087?productId=3129237&pl=1&currentURL=/pl_Load+Centers+_4294821909_4294937087_?rpp=15$No=345 and being sure the buss can handle the number of pv string inputs along with the gauge wire being used. you would want either fuses or breakers if more than 2 strings of pvs and that could be homemade too, but i would not have this exposed to the weather unless in a good outdoor rated electrical box. if using the + and - buss in the same enclosure it may need mounted on something like a block of plastic or even wood to avoid shorting out when in metal boxes.

    as to the lightning we have had many discussions here on that subject. one can go elaborate and still get a lightning strike so with lightning there are no guarantees, but efforts do help in your odds if done right. it starts with a good ground system from pv to the ground rod following nec requirements although i dispute one aspect they initiated. check some of the products our host sells for this purpose with the store link at the top of the forum.
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  • mike95490
    mike95490 Solar Expert Posts: 9,583 ✭✭✭✭✭
    #3
    Re: Putting the pieces together
    bfitzgerald wrote: »
    One other thing that I would ask about is lightning protection - I did lose most of my system including the charge controller, lots of lights, and stereo to lightning. I'd like to try to protect against this in the future!

    If your area gets lightning often, put up a couple tall flag poles as "decoys" for the lightning to hit, instead of your expensive stuff. The further you can keep the strikes away from your gear, the better. Be careful of multiple grounds, if you do get a strike, the current in the soil may decide your multiple ground rods and interconnecting wires are better to travel through.
    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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  • bfitzgerald
    bfitzgerald Registered Users Posts: 26 ✭✭
    #4
    Re: Putting the pieces together

    Thanks for the reply. The system I am replacing is an ungrounded 12v battery system with a simple 400 w inverter. I was amazed at the damage caused by the lightning strike - I wasn't there when it happened (thankfully), but my guess is that the lighting struck the ground (rock) about 30 feet from the cabin and travelled along tree roots and entered the cabin right under the propane tanks. It blew pots and pans and some wood out of a lower cupboard and somehow entered the DC wiring doing a lot of damage to components. About 30 feet in the other direction I had a 12v battery under a shed charged by a small solar panel and charge controller all to run a light. The battery, which was under the shed on some boards had its' top blown off.

    In my original post on putting the new system together I was hoping for someone to tell me that I should buy the Midnite Solar XW e-panel or in the alternate advise me as what else I need purchase to safely finish off this off-grid installation.

    Thanks,

    Brian
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  • niel
    niel Solar Expert Posts: 10,300 ✭✭✭✭
    #5
    Re: Putting the pieces together

    believe it or not from what you describe, i don't think the lightning hit your stuff even though it's possible it did. i believe the emp of the strike did the damages you saw. we have had ample discussions on emp as well and like lightning you have no guarantees, but you can minimize the possibility if done right.
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  • Kamala
    Kamala Solar Expert Posts: 452 ✭✭
    #6
    Re: Putting the pieces together

    Yeah, lightning protection/amelioration is a tough problem to address.

    I've had two close calls in my <60 years. First one is chronicled here and, since it is sufficiently distant in my past, I wear the "badge" proudly.

    The second occurred more recently. Maybe within the last 10 years? But unchronicled until now.

    Early morning shower prep for work in thunderstorm. Lighting flashes and not so distant thunder. Same kind of milli/micro second premonition as in camp story. Duck. BOOM. No shock this time (fiberglass tub?) but, having had experience, knew by magnitude of boom, was close. Lights flicker but don't go out. Didn't lose power. Went to work. Came home. TV, stereo and computers don't work. Lights are on and never lost power.

    Long story short... opened as many devices as I could to find AGC type fuses. (Could not open Bose Wave Radio... sent in for $300 upgrade... :confused::cry::grr ) Replaced them. Worked fine. Of greatest interest was gaussing of CRTs. Rainbow patterns like I have never seen! And I have spent some time putting permanent magnets on these things just for fun.

    Theory: Wiring in the house (large loops?) inducted the EMP after the breakers/surge protection.?

    Dunno. Hope the stories were good.

    For my camper? There is a 60 foot tree nearby. Hope it takes the hit. But then there is wind... which is another story.

    KAMALA
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  • bfitzgerald
    bfitzgerald Registered Users Posts: 26 ✭✭
    #7
    Re: Putting the pieces together
    mike90045 wrote: »
    Be careful of multiple grounds, if you do get a strike, the current in the soil may decide your multiple ground rods and interconnecting wires are better to travel through.

    If I read you correctly is there a bigger danger of getting a strike if you have two ground rods 10' apart (as per the code around here)?

    Brian
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  • mike95490
    mike95490 Solar Expert Posts: 9,583 ✭✭✭✭✭
    #8
    Re: Putting the pieces together
    bfitzgerald wrote: »
    If I read you correctly is there a bigger danger of getting a strike if you have two ground rods 10' apart (as per the code around here)?

    No, it's if you have a near strike, and you get a lot of current flowing in the dirt, and suddenly, it sees a nice piece of copper wire (say a ground rod at your PV array) and follows a copper wire to your service entrance (another ground rod) and then, just 'cause it's onery, it frys everything in your house, looking for some more copper going to ground (where you tied an outlet to a cold water pipe). Keeping all the stuff properly grounded, but not always tied to each other, is quite a science. i prefer to distract it with well grounded flag poles with no connection to my house wires
    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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  • BB.
    BB. Super Moderators, Administrators Posts: 33,637 admin
    #9
    Re: Putting the pieces together

    Generally--If your place requires multiple ground rods (poor/rocky soil)--Put your rods in a star or circle--and run all of the wires back to center (or common point)... Then make your home's ground connect to that one point. That way, any current in the ground is shorted through the wires between the rods instead of being driven into your home's ground wiring.

    To a degree--you will end up with equipment being damaged by lighting strikes--and if you can disconnect (by feet) your critical equipment before a storm hits--you will be better off...

    For example, disconnect your antenna cables. And you can disconnect your solar array from your battery bank (again, pull the cables feet away, no standard switch is going to work).

    And realize, that you still may end up needing to replace the inverter because its AC output blew.

    Here a a couple threads about lightning...

    Off Grid Grounding Technique?
    Another Question, this time about Lightning

    There are many opinions about protecting against lightning--and some of the old standard practices are actually not helpful.

    If you know a HAM radio guy in your area--ask him. Perhaps he can give you some suggestions for your area.

    -Bill
    Near San Francisco California: 3.5kWatt Grid Tied Solar power system+small backup genset
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  • niel
    niel Solar Expert Posts: 10,300 ✭✭✭✭
    #10
    Re: Putting the pieces together

    i'm curious how they have the 2 ground rods connected. did they just run 2 wires to the 2 separate rods or just 1? did they connect the rods together as well with a large bare copper wire underground?
    the 2 rods will not increase the likelyhood of you getting hit imho.
    ps. not all hams are grounding experts.
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  • bfitzgerald
    bfitzgerald Registered Users Posts: 26 ✭✭
    #11
    Re: Putting the pieces together

    The conductor to the other ground rod must be at least #6 copper and is usually a continuation of the service grounding conductor. This conductor is threaded through the first ground clamp then continues to the clamp on the second ground rod. The conductor should be buried to reduce trippping hazzard.
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  • niel
    niel Solar Expert Posts: 10,300 ✭✭✭✭
    #12
    Re: Putting the pieces together

    sounds good to me and yes bury it. at least a ft down is my way of thinking as soil erosion and accidental cutting of it through even minor gardening could happen. the bare copper wire in contact with the soil will also contribute greatly to a better ground and not just the fact it connects to another rod. the 2 interconnecting rods increase the better distribution of the lightning into the soil should it hit.
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  • dsp3930
    dsp3930 Solar Expert Posts: 66 ✭✭✭✭
    #13
    Re: Putting the pieces together

    The Midnite E-Panel is what I have so I'll comment on it.

    It makes for a pretty clean installation and comes with all the main breakers you need on the AC side and a DC main battery breaker. You also will likely need to purchase two 63A DC breakers, 1 63A DC GFI breaker, three Delta AC 120/240v lightning arrestors, and one Delta DC lightning arrestor. The connection to the Xantrex main DC power lugs is pretty neat using direct bolts between the epanel and inverter. The nicely labeled bus bar connects for AC1, AC2, Load, Battery, PV, Ground, and Neutral are convenient and easy to use. If you are not planning on linking another Xantrex into the mix with the first, then I think the E-Panel is the way to go. As a side note: NAWS has probably the lowest price on this item anywhere at $760 plus maybe $20-30 shipping to Ohio. I bought mine here.

    If you do get it, remember that it sits below your inverter. Make sure you have adequate ground clearance. Also, all the knockouts are on the bottom except for the ones on the side to connect to your charge controllers.
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  • jeffkruse
    jeffkruse Solar Expert Posts: 205 ✭✭✭
    #14
    Re: Putting the pieces together

    I second the Midnite E panel.
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  • stevend
    stevend Solar Expert Posts: 34 ✭
    #15
    Re: Putting the pieces together

    I third the Midnite solar E-Panel. I've never done the XW verison but I've done plenty of the Outbacks, Magnums and even used their plain version to mount a Flexmax80 on the door.

    My main reason for recommending it, especially if you're installing yourself, is that all the bells and whistles are there. Too often I have to repair an installation where the installer didn't include something that should have been there or wired something incorrectly - such as sending both generator output and inverter output to the breaker panel. Make full use of the E-Panel and there's less chance you'll do it wrong. That's includes using the included din rail to add the breakers that dsp3930 recommended and using knockouts for any lightning arrestors you choose to put in the E-Panel (sometimes I can put the DC one on the charge controller.)

    Follow the manuals... but if you need further reference, these pages detail a recent E-Panel job I did, photos, labels, diagrams and all.
    http://rimstar.org/renewnrg/sp_off_grid_solar_power_rv_motor_home.htm
    Warning, the wiring in the E-Panel isn't as pretty as I'd like but the wires I had were very stiff so I had to leave some looseness (hey, we'll save money by buying wire with less strands. hey, you just cost more in installation time - sorry, ranting :)).
    -Steve
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  • bfitzgerald
    bfitzgerald Registered Users Posts: 26 ✭✭
    #16
    Re: Putting the pieces together
    dsp3930 wrote: »
    ...You also will likely need to purchase two 63A DC breakers, 1 63A DC GFI breaker,...

    Thanks for the help on the e-panel. Reading the comments I am sure that is the way to go. I'm assuming that the 63A DC breakers are for the charge controller circuit (array in and out) and are also charge controller and array disconnects. The GFI is for the array - charge contoller circuit? In addition to the breakers I think that all I will need is a small array combiner (MNPV3) and a couple of breakers.

    This sure is a lot more complicated that my old auto fused system!

    Thanks again

    Brian
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  • jeffkruse
    jeffkruse Solar Expert Posts: 205 ✭✭✭
    #17
    Re: Putting the pieces together

    Does your CC have the GFI built in? The XW does.
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  • bfitzgerald
    bfitzgerald Registered Users Posts: 26 ✭✭
    #18
    Re: Putting the pieces together

    Very nice documentation on the motorhome. I'll have to go through it again as I prepare my project.

    Thanks for sharing the information.

    Brian
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  • bfitzgerald
    bfitzgerald Registered Users Posts: 26 ✭✭
    #19
    Re: Putting the pieces together

    I'm going to be using the Xantrex XW-SCC.....
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  • jeffkruse
    jeffkruse Solar Expert Posts: 205 ✭✭✭
    #20
    Re: Putting the pieces together

    Good, then IIRC the GFI is built into the XW.
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  • bfitzgerald
    bfitzgerald Registered Users Posts: 26 ✭✭
    #21
    Re: Putting the pieces together

    This may seem like some dumb questions....but here goes. I will have two strings of 3 of 200w panels, (Voc 36.2, Isc 7.68 ). I plan to combine these strings in a Midnite MNPV3 using 2 - 15 amp breakers. You suggest that I use 63 amp breakers on both the battery side and the array side in the e-panel. Why not use an array side breaker rated below the 60 amp maximum of the Xantrex SCC? Is it because the combiner 15 amp breakers protect the input side of the controller and the 63 amp breaker is another array disconnect but inside the e-panel? Also, as Jeffkruse pointed out, the SCC provides GFP for the array so I think that I can skip the GFP breaker.

    Thanks for your help.

    Brian
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  • BB.
    BB. Super Moderators, Administrators Posts: 33,637 admin
    #22
    Re: Putting the pieces together
    bfitzgerald wrote: »
    This may seem like some dumb questions....but here goes. I will have two strings of 3 of 200w panels, (Voc 36.2, Isc 7.68 ). I plan to combine these strings in a Midnite MNPV3 using 2 - 15 amp breakers. You suggest that I use 63 amp breakers on both the battery side and the array side in the e-panel. Why not use an array side breaker rated below the 60 amp maximum of the Xantrex SCC? Is it because the combiner 15 amp breakers protect the input side of the controller and the 63 amp breaker is another array disconnect but inside the e-panel? Also, as Jeffkruse pointed out, the SCC provides GFP for the array so I think that I can skip the GFP breaker.

    For two parallel strings, you do not need any combiner box breakers/fuses. It is impossible to over current either of the two parallel strings with a short circuit. If you have three or more parallel strings, then you should have a series fuse/breaker in each string.

    Isc for each string is around 15 amps maximum (typical series fuse for this size panel--just guessing). Two arrays together cannot supply more than 30 amps (realistically, 20 amps). So having a 63 amp breaker on the input is just a power switch (many people like a panel disconnect switch--nothing wrong with that).

    Remember, breakers/fuses are their to protect the wiring. If you wire for 60 amps (really 80 amps, 60 amps * 1.25 NEC safety factor for circuit capacity = 75 amps minimum, round up to 80 amps)--then 63-80 amp breaker would be appropriate.

    If, how ever you where to size your wiring for a ~20 amp continuous circuit, and size it for 30 amp rating--Then the appropriate sized breaker/fuse would be 30 amps.

    Breakers/fuses are not their to "protect the device" from damage in a failure. They are there to protect the wiring (and by extension, the input/output wiring of the device) so that if there is a failure, it will not cause a fire, but instead trip the breaker and prevent the wiring from overheating and causing a fire.

    -Bill
    Near San Francisco California: 3.5kWatt Grid Tied Solar power system+small backup genset
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  • niel
    niel Solar Expert Posts: 10,300 ✭✭✭✭
    #23
    Re: Putting the pieces together

    that applies to short circuits of the normal kind, but wire a string backwards and woo hoo. fuses are not required for 2 strings, but it can't hurt.
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