Oncered: Newbie 250 Watt system install questions

BB.BB. Posts: 27,694Super Moderators admin
This discussion was created from comments split from: newbie solar truck camper setup.
Near San Francisco California: 3.5kWatt Grid Tied Solar power system+small backup genset

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  • onceredoncered Posts: 2Registered Users
    As another "newb", is it ok for anyone to jump in here? I too have a TC, though not in Mexico, but still in a sunny place and I'm about to start installing a 250 watt system and have a couple very  specific questions about the nuts and bolts of the connectors, fusing and maybe something else. May I ?
  • vtmapsvtmaps Posts: 3,738Solar Expert ✭✭✭✭
    oncered said:
    As another "newb", is it ok for anyone to jump in here? I too have a TC, though not in Mexico, but still in a sunny place and I'm about to start installing a 250 watt system and have a couple very  specific questions about the nuts and bolts of the connectors, fusing and maybe something else. May I ?
    Welcome to the forum.

    make a new topic to discuss your questions... it's less confusing that way.   --vtMaps
    4 X 235watt Samsung, Midnite ePanel, Outback VFX3524 FM60 & mate, 4 Interstate L16, trimetric, Honda eu2000i
  • BB.BB. Posts: 27,694Super Moderators admin
    Welcome to the form Oncered,

    I moved to your own thread... Usually it keeps "discussions" a bit easier to follow--This thread is "yours"--So ask the questions you need to ask.

    I suggest that you ask a few (related) questions at a time. Asking 20 Questions at once really can get confusing when folks answer different pieces.

    So continue on here.

    -Bill
    Near San Francisco California: 3.5kWatt Grid Tied Solar power system+small backup genset
  • onceredoncered Posts: 2Registered Users
    edited June 2016 #5
    Thank you, here goes.
    • 1. The wire coming from the box back of the solar panels is #10 and I am going to increase the size of the wire. Not wanting to use MC4, is an automotive type crimp connector satisfactory to join the wires? 
    • 2. The battery monitor install instructions, (Trimetric) describes installing it first; is there an advantage to having a post for all the pos wiring to connect to rather than stacking on a battery positive terminal on the battery?
    • 3. The battery cables native tot he camper seem small to me, (wire size is indeterminate), is it likely to be beneficial to build new ones, equal in length and all that while the batts are out and the monitor is being installed?
  • BB.BB. Posts: 27,694Super Moderators admin
    Yes, you can use automotive crimp connectors... Just seal them from weather (J-box, tape, etc.). There are lots of other options too... One is to use "bus bars" in plastic J-boxes). You want rugged/reliable/safe connections--Solar power can be a bit more "difficult" than AC circuits--Solar runs near maximum rated current for hours per day on hot roofs... Most people only run their AC applanices and wiring at much less than "rated" capacity (erroring on "oversizing" wire gauge is not bad :

    http://www.solar-electric.com/installation-parts-and-equipment/midnite/brbusbatebus.html bus bars
    http://www.solar-electric.com/catalogsearch/result/?q=distribution+panle&cat=0 Insulated power distribution blocks

    Poster 2manytoys has documented his many years of evolving solar power system design/installation--Including a lot of DIY type projects:

    http://2manytoyz.com/ (solar is ~2/3rds way down on the right side of the page)

    Are you using 2x 125 Watt panels in parallel? Length of wiring and current determine the actual AWG of wire needed... You can use a voltage drop calculator and figure out the "optimum" wire size (typically 1-3% voltage loss for wiring is common in solar):

    http://www.calculator.net/voltage-drop-calculator.html

    A few wires/stacked ring lugs is typical... But as you grow the system, it is better to use bus bars and distribution panels. Every + wire that leaves a bus bar should have its own breaker/fuse (i.e., 14 AWG wire should have ~15 amp fuse/breaker). If you have lots of DC (and AC) connections, you should look at true breaker/distribution panels:

    http://www.solar-electric.com/installation-parts-and-equipment/midnite/elenanddcdi.html

    If you are paralleling batteries for your bank, see here:

    http://www.solar-electric.com/batteries-meters-accessories/bach2/me-sbc.html

    For your RV wiring... You need to define loads and charging current--Then design the wiring/fusing/breakers to support those expected current flow. The Original RV wiring probably supported a few lights, fan and a few other loads. Your are adding to the overall system now (I guess).

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