Solar Wire Size..??? Fuses on panels...??

[Rbertalotto]

Ok, ready to install my solar system and I need to buy wire to go from panels to the solar controller

Two, 140W panels, wired in parallel

Here are the specs on the panel:



The wire length of run from panels to controller will be 30-35'

I'm a bit confused on wire size......

Also, do these panels need to be fused at the panels? If so, what size fuse.

I really appreciate all the help this forum has afforded me over the years. Hope to repay it someday.

[MEXICOWANDERER]

pianotuna wrote:
Muddy,

Some of us are power hogs! I use up ever watt my solar panels produce and then some.

Power Hogs?

I RESEMBLE THAT REMARK!
(oink, squeal, snort) 🙂 🙂 🙂

[Johnny_G1]

I may be wrong but balance is better, looks like you will be drawing all your power from the one battery, I have 8 batteries in my rig since 2003 and they are still right up there with a hydrometer, worth a try. Just my thought's.

[grizzzman]

Rbertalotto wrote:
The batteries are wired in parallel. I didn't think it mattered where I connected my + and -. I simply went to the closest battery.

In a "series" connection you would need to connect to the "beginning" and the "end" of the series, but in parallel I don't believe it matters.

Someone correct me if I'm wrong.

Your wrong.........You can stand corrected 🙂

[Rbertalotto]

Why do you have 2 + and only 1 -

This system used a Bogart Trimetic monitor. This is how it is wired. The house load negative (-) and all other negativeness go to a shunt mounted in the trailer. Therefore only one negative wire to the batteries. At the shunt, the negative from the solar controller and the house negative on one side and the other side of the shunt goes to the negative of the battery pack.

The 3 positives are from the solar controller and from the house positive and from the second battery.

With every negative going through the shunt, the Trimetric can "READ" all current going into and out of the battery bank.

[Rbertalotto]

Well how about that. You learn somethimng new every day. I didn't think the resistance in a 18" piece of #2 wire would add up to anything on a two battery system. Although extremely small, it is still there.

I'll be moving the negative wire to the far battery as stated here.

http://www.smartgauge.co.uk/batt_con.htmlhttp://www.smartgauge.co.uk/batt_con.html

Thanks for pointing it out.

[Muddydogs]

Well the word is you need to balance the batteries which in your case you would have the + coming off one battery and the - coming off the other. Why do you have 2 + and only 1 - not counting your parallel cables?

Very nice box, bet it lasts you a few years.

[red31]

why not balance them?


http://www.rv.net/forum/index.cfm/fuseaction/thread/tid/28531228/srt/pa/pging/1/page/5.cfm

[Rbertalotto]

The batteries are wired in parallel. I didn't think it mattered where I connected my + and -. I simply went to the closest battery.

In a "series" connection you would need to connect to the "beginning" and the "end" of the series, but in parallel I don't believe it matters.

Someone correct me if I'm wrong.

[red31]

why does the far battery have only one lead on both terminals?
I'd expect the two center terminals (one from each battery) to only have one.

[Rbertalotto]

Today I finished the solar install....

Had to build a battery box to hold two Group 31 batteries and a little extra room for a future circuit breaker (on order).

The box was made out of simple birch plywood and coated with two coats of truck bed liner. At some point I'll replace it with a diamond plate aluminum version. Just didn't have time and $$ to do it now.



Had to make a little "Side Car" to fit everything as the batteries took all the distance between the hitch frame.



The top is removable and secured with a couple of padlocks







Vents supply fresh air and let it breath.

Lots of cutting, crimping and heat shrinking! I think it came out nice!



Hooked it all up, threw the battery disconnect switch and everything worked perfectly! It was 3:30PM when I threw the switch and the Trimetric was showing the batteries were receiving a charge. Batteries were at 12.85V (new batteries, never installed) and after an hour they were at 13.1V...Nice!

Can't wait to give it a real shakedown next weekend!

Lots more on my website

www.rvbprecision.comwww.rvbprecision.com

[CJW8]

Good find on the welding cable and you won't be sorry you went with the larger size. I couldn't find if you said if you are using PWM or MPPT but if you are using PWM controller, and you later decide to upgrade to MPPT, you'll be glad you used the larger wire.

[Rbertalotto]

Crabby patty...sounds like you got it figured out! Gotta love solar!

[Crabbypatty]

I used 10/3 out door cable to connect panels to combiner box with circuit breakers. Longest run was around 6 feet. From the combiner to the controller was a long run maybe 45 feet or so and used the same 10/3 cable to the controller a Morningstar ts 45 a PWM unit. I went through all of this set up with the Altestore before I did it and bought the controller and combiner box from them. 10/3 was all I could find where I live from the electrical supply house. Last week was the trial run, dry camping on the beach for 7 days. Never used the generator once! 4 112 watt panels and all of this goes into tow Trojan t125's. I utilized a Bogart engineering battery monitor to see how I was doing. Charging started as soon as 8 am and went all the way to 4 pm ish before the sun got to low. The batteries charged all the way except for one day a little hazy. Two adults and two college kids charging laptops, phones ipads, water pump for dishes showers, TV's and lights, and it was successful. I have two more panels that I am going to install shortly and perhaps two more Trojans. Most of the dry campers have a 4 battery set up.

[westend]

Good work!
Two items noted that you may want to address in the future: Shrink wrap on your cable terminations helps prevent oxidized wires. It looks like your junction box has a standard "pull-through" box entry. Waterproof box entry fittings are available or fill the holes around the cables with sealant. Your 3M sealant would work well there but will make retro work difficult.

Looks like you have every other thing well organized. Good luck finishing up the install!