Where to buy wire? Lots of local trouble ...

HRTKD

Boondocker
Joined
Apr 24, 2020
Messages
5,937
Location
Somewhere South of Denver
THat’s a real problem with a 50 amp controller and a 35’ RV if you want to parallel panels. Large voltage loss on a 12 volt system approaching 50 amps with all panel parallel. RV roofing has a lot of shading. Aside voltage loss if the insulation is rated at 60 C and 55 amps, why would I want to risk my wired getting hotter than that when roof temps are 135 - 155 F and then the wire goes down through conduit. 50 amps may raise the temp.

Sure there’s things you could do like get 90 C or 105 C rated wire, but I still want to avoid losses.

Some people don’t care about voltage losses. I do.

I'm with you there. There's only so much wattage I can put on the roof of my RV. Voltage loss is not something I take lightly at all.
 

anadiner

Solar Enthusiast
Joined
Aug 10, 2021
Messages
300
To this point, my Victron solar charge controller's technical specification lists the maximum wire gauge for the PV input and battery output at 6 awg. I made sure to use wire that wasn't any larger than that, which as you said would be a waste, unless there was a very long run of the wire.
Cabling is an area that I pay extreme attention to: its something I never want feel need to upgrade or replace. And may reuse.

This is unlike an inverter, panel or battery itself.

I prefer 0 gauge for batteries where I use 4 12v/100ah batts - 2 strings of 2 in series (24v/100ah) then in parallel (24v/200ah) rendering 4800wh and a 24v system .

Thats my preference.
4 awg = max 60 amps
3 awg = max 85 amps
2 awg = max 95 amps
1 awg = max 120 amps
0 (1/0) awg = max 150 amps

Thats general come by memory but also keep in mind, length. Thicker gauge is needed when adding length. IE) the only way I would put batteries side by side is with pieces if welding blanket as spacers.

Good point not to tamper with controller trying to make/force a wire to fit. Guess thats y this is a common problem.
 

sidpost

New Member
Joined
Mar 27, 2021
Messages
29
Location
Texas, USA
Heat build-up, resistance, voltage loss, run lengths, etc. are all valid concerns up to a point of diminishing returns.
 

Alphacarina

Solar Enthusiast
Joined
Feb 22, 2021
Messages
215
My point was messing with a controller to install an oversized wire gauge you don't really need. Sure, a larger gauge wire is generally better if weight and cost aren't a problem but, you don't really need a large wire to run small amperage levels.
The size of the cable required is determined not only by the current in the circuit, but also by the length of the cable. My (limited) experience with controllers is that they all seem to have questionable contact points which barely support adequate sized cable, even for short runs. My practice is to run the cable size required - and I often go one size larger than required - and I run that to a buss bar mounted as close as possible to the controller and then run a very short piece of cable which will fit the controller between it and the buss bar

The only disadvantage of oversizing your cable by a little bit is the cost of the cable - When you decide at a later date to add a couple more panels, that disadvantage goes away pretty quickly

Don
 

OffGridInTheCity

Solar Addict
Joined
May 23, 2021
Messages
427
Location
Southern Oregon
I use Wire and cable your way: https://www.wireandcableyourway.com. Wire and cable your way comes in within a week. I've also used Amazon.

I do not like the idea of custom made cables. It's more of an inability for me to measure things accurately than a hit on whoever makes them. Particularly hard was figuring the placement and lengths of my panels before they were on the roof. Even after I secured them to the roof, I thought I'd use 60' of cable but used 90'. Also have to make sure the pre-crimped connectors will fit through whatever hole they are supposed to.
I also use Wire and Cable your way over the last 3 years. 1000(s) of feet, 10+ different orders (welding cable, PV cable, 6 awg bare twisted copper for busbars, underground cable to run combined ground mount PV into the house, and regular AC wiring). Good results all around.

One time, I accidentally ordered unmatched 'stranded wire counts' between equal lengths of red/black (for battery bank wiring) and they contacted me to confirm and after discussion, changed the order for me to have them match. Not a huge deal - but was pleasantly surprised.
 
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anadiner

Solar Enthusiast
Joined
Aug 10, 2021
Messages
300
The size of the cable required is determined not only by the current in the circuit, but also by the length of the cable. My (limited) experience with controllers is that they all seem to have questionable contact points which barely support adequate sized cable, even for short runs. My practice is to run the cable size required - and I often go one size larger than required - and I run that to a buss bar mounted as close as possible to the controller and then run a very short piece of cable which will fit the controller between it and the buss bar

The only disadvantage of oversizing your cable by a little bit is the cost of the cable - When you decide at a later date to add a couple more panels, that disadvantage goes away pretty quickly

Don
Thx. Makes sense using the bus bar which unfortunately, my homemade microinverter build isnt... hence my problem.

Did find some controllers that have larger slots but pricey. Defeats microinverter concept. Looks like I may have to rethink and have components closer than planned.
 

Joe BoyKey

Watts, Watts, more Watts
Joined
Sep 11, 2020
Messages
454
Location
Austin Texas
 

sidpost

New Member
Joined
Mar 27, 2021
Messages
29
Location
Texas, USA
Thx. Makes sense using the bus bar which unfortunately, my homemade microinverter build isnt... hence my problem.

Did find some controllers that have larger slots but pricey. Defeats microinverter concept. Looks like I may have to rethink and have components closer than planned.
When you say "microinverter", it implies a really small solar panel. That being said, worrying about 10/8/6 gauge wire is probably massive overkill. 12 gauge or smaller wire may actually be all you need for a few amps (<3A) and a low voltage (~12~18Vdc) from a small solar panel.

Knowing the wattage, voltage, and amperage of your panel would help 'quantify' what wire sizes are appropriate for your application along with run lengths if more than a few feet.
 

Boondock Saint

Solar Addict
Joined
Apr 8, 2021
Messages
658
Having his own thread would also help quantify.

Sidpost did you find the cable in the short lengths and prices you were looking for? If so, what did you end up getting?


.
 

anadiner

Solar Enthusiast
Joined
Aug 10, 2021
Messages
300
When you say "microinverter", it implies a really small solar panel. That being said, worrying about 10/8/6 gauge wire is probably massive overkill. 12 gauge or smaller wire may actually be all you need for a few amps (<3A) and a low voltage (~12~18Vdc) from a small solar panel.

Knowing the wattage, voltage, and amperage of your panel would help 'quantify' what wire sizes are appropriate for your application along with run lengths if more than a few feet.
Right. I forget on thus forum that once uve discussed what ur doing... doesnt mean everybody knows.

Hence, doing 2 projects.
1) A regular build coming later using all UL Listed and a ground mounted array. This is a permanent build for house being built after losing mine to fire.
2) Im throwing together a temp build for while Im in temp housing (camper) on my property. Note: cuz of Code Ordinance I cant turn on nor hookup to any utilities BUT can do solar or a generator.
Sooo Im throwing together a build using 24v inverters like microinverters in order to keep wiring and electrical minimal. Im designating each inverter to specific items IE) frig and fan. Calculate about 300w per battery. Note: 24Vs also cuz lead-acid due to temp

I was interested in this post cuz looking for wiring that will reuse and cuz cheap crap for now, as fire resistant as possible.

Micro concept but will need more controllers.

Wondering what ave used awg is used for 24v bank from 2 12v flooded lead-acid. Im ordering cable by tomorrow. Is my last phase.

Gonna use one of the suggested sites.
 

sidpost

New Member
Joined
Mar 27, 2021
Messages
29
Location
Texas, USA
Having his own thread would also help quantify.

Sidpost did you find the cable in the short lengths and prices you were looking for? If so, what did you end up getting?


.
I got two reels of wire and a bag of MC4 connectors so I can make the lengths I need and have some wire for my next project.
 

sidpost

New Member
Joined
Mar 27, 2021
Messages
29
Location
Texas, USA
TEMCO 8AWG 250 foot reels are $153 each. 8AWG will give you a lot of "room to grow" your solar system before amperage limits become a problem. 8AWG probably isn't enough for a whole house system though it would be a lot for a small cabin or travel trailer and most likely overkill for the wattage of small systems designed for those applications.
 

Boondock Saint

Solar Addict
Joined
Apr 8, 2021
Messages
658
I bought the Windy Nation #8 and everything from the panels back to the SCC's are #8. I have 2 sets of panels in series.

I need 2 x 3' jumpers between panels, I'm cutting the 10' into a 3' and a 7' home run w blank ends, and I'm cutting the ends off of the 50' and them cutting in two for the runs to the SCC.


Your Cart​



Product Price Quantity Total
1 Pair Black + Red Solar Panel Extension Cable Wire Solar Connector 8 Gauge (AWG), 10 Gauge (AWG) or 12 Gauge (AWG) 3 ft. Red + 3 ft. Black 8 AWG CBL-SLRRB-08-3 Feet: 3 ft. Red + 3 ft. Black Wire AWG (Gauge) Size: 8 AWG $18.16


$83.78

$150.75 Subtotal:

$150.75
 
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