Solar Wire

[dspurgeon]

Solar Wire: I have a quandary involving the wire used to wire my solar panels. I did hours of research and finally purchased two Kyocera 140 Watt solar panels (which will mount on a SS frame constructed above the davits of our Hunter 38) and a Morning Star TriStar MPPT 45 amp controller. I will have room for an additional panel and the controller will if necessary, handle the additional load). Through several sites I obtained wire sizing charts and recommendations to maintain a 2% loss in the runs necessary. I therefore intend to run #4AWG from each panel wired in parallel to the Combiner. There each panel will be on a 15 amp fuse, (either could be shut down without affecting the other). Then I will run #2AWG to the Controller then onto the house bank (20amp fuse in line prior to battery). The house bank consists of two 40-1000 Crown batteries. Each battery reserve capacity is 300 min @ 25 amps. Amp hour Capacity is 20hrs = 7A and 140Ah, 10hrs = 13.2A and 132AH, 5hrs = 25A and 125Ah.
I am having difficulty finding wire. I need 84 feet #4AWG and 60 feet #2AWG. The #4AWG should be UV resistant. The questions I have are these.
1. Where do I obtain the wire? The solar panel sites do not sell these sizes. (see #2 legality)
2. According to ABCY and Federal standards as I read it, I am required to have stranded approved wire that is also color coded. I have been unable to find this size wire other than listed as marine battery cable or welding cable and it is expensive.
3. Is standard home store obtained stranded THNN legal.
4. What wire can I use, standard stranded wire or special marine wire, and where can I obtain it?
Mainsail, thank you. Your site, photos, and various forum advise was very helpful and appreciated in this project. This forum also has been a site of inspiration and gained knowledge for me, Thanks to all.

 

[anchorclanker]

After some reading, I would use the marine grade. The stuff is tinned to prevent corrosion.

I found this.. http://www.delcity.net/store/4-ga-Tinned-Wire/p_656655

Just google "marine grade wire", theres a bunch of links.

 

[Chef2sail]

http://shop.genuinedealz.com/Marine Grade Wire/

 

[Bob 04 H260]

Solar Wire: I have a quandary involving the wire used to wire my solar panels. I did hours of research and finally purchased two Kyocera 140 Watt solar panels (which will mount on a SS frame constructed above the davits of our Hunter 38) and a Morning Star TriStar MPPT 45 amp controller. I will have room for an additional panel and the controller will if necessary, handle the additional load). Through several sites I obtained wire sizing charts and recommendations to maintain a 2% loss in the runs necessary. I therefore intend to run #4AWG from each panel wired in parallel to the Combiner. There each panel will be on a 15 amp fuse, (either could be shut down without affecting the other). Then I will run #2AWG to the Controller then onto the house bank (20amp fuse in line prior to battery). The house bank consists of two 40-1000 Crown batteries. Each battery reserve capacity is 300 min @ 25 amps. Amp hour Capacity is 20hrs = 7A and 140Ah, 10hrs = 13.2A and 132AH, 5hrs = 25A and 125Ah.
I am having difficulty finding wire. I need 84 feet #4AWG and 60 feet #2AWG. The #4AWG should be UV resistant. The questions I have are these.
1. Where do I obtain the wire? The solar panel sites do not sell these sizes. (see #2 legality)
2. According to ABCY and Federal standards as I read it, I am required to have stranded approved wire that is also color coded. I have been unable to find this size wire other than listed as marine battery cable or welding cable and it is expensive.
3. Is standard home store obtained stranded THNN legal.
4. What wire can I use, standard stranded wire or special marine wire, and where can I obtain it?
Mainsail, thank you. Your site, photos, and various forum advise was very helpful and appreciated in this project. This forum also has been a site of inspiration and gained knowledge for me, Thanks to all.

I think you have good advice above, Genuinedealz is a good place to buy it and they can even do the terminations for you too.
If you could get away with one larger panel the higher voltage/lower current might have saved money on the wire size needed.
Are you certain about the length of the runs they sound very long for a 38 ft boat ?
I am looking at doing a similar installation but intend to put at least one panel over the arch and have been looking at the bigger panels because of the higher voltage output will save some money on the wire size required. Also my battery bank is located below the arch so the runs will be much shorter.

Good luck on your project and please post some pictures as you progress, Bob

 

[Maine Sail]

Some thoughts:

144' or 72' of one way wire from the panels to the battery on a 38' boat? That's a lot of zig zagging

#1 I would try darn hard to find some wiring near the aft end of the boat that leads directly to the house bank and make use of that wiring. For instance if your house bank goes to position #1 on the battery switch then you can tie into that wire at the battery switch. If you have an inverter/charger in the aft end of the boat that ties directly to the house bank use that wire.

#2 Unfortunately there is no such beast as UV protected marine wire. It holds up pretty well but not as well as wire intended for outdoor extension cords or a dedicated solar wire. I really dislike solar wire as the stranding is too large for boats. A UV stable SOW, STW, STOW, SEOW, or STOOW type cable can work well and can often be ordered in sizes up to 6/2. With proper terminations you really don't need a tinned wire just a finely stranded good quality copper wire with a 105C jacket temp rating.

#3 If shading won't be an issue you can always go with a series panel connection and a controller that can handle the voltage. This will drastically cut the wire gauge size between the panels and controller.

#4 With the amount of wire you need you may be much better off with two Genausn GV-10 MPPT controllers, one for each panel. This is the preferred method when installing Genasun controllers as it allows each panel to be tracked independently and its output optimized.. This would likely get you into the boat with 8-10GA duplex wire then off to the battery wiring with larger cable.

#5 There is no need for fusing before the controller. It just adds connections and potential for voltage drop. The fusing needs to be within 7" of the battery bank or where you "tie in" to the 12V system with a smaller wire than is already protected.

#6 If you parallel the panels the parallel wire only needs to be sized for the one panels output and the length between it and the next panel. 10GA wire is more than sufficient for the parallel jumper for a Kyocera 140. For example a 4' 10/2 parallel jumper wire at 7.5A drops 0.52%....

 

[dspurgeon]

The panels will be mounted on a SS frame above the davits at a height equal to the Bimini to obtain the most sunshine. From the information that I obtained, this will help prevent shading from the Bimini which results in a lesser performance. Mounting on the arch would have resulted in more shading problems due to the boom/mainsail. Our boom extends almost to the rear of the Bimini. Wiring in parallel instead of series reduces the effects of shading as one panel being shaded will not affect the others output as it does in series. But, it does use more wire and of a larger gauge. It comes down to do you want better performance or save cash on wire.
As to the wire footage. The starboard panel to combiner/controller will be 25ft and the port will be 17ft. From the controller to hose bank is 30ft. Each figured run is then doubled as two wires (+/-) must be ran for each. One battery is located under the seat way north near the compression post area. Wiring to the battery switch as Mainsail suggested would also save footage. Now I think I can save on the panel run also by connecting the two panel grounds together thereby running two positives and only one negative to the combiner.
If I connect the positive to the back of the battery switch, where does the negative connect? From standard schematics it shows the controller connecting to the positive on one battery and to the negative of the other battery. Would the switch have to be in a certain position or do I connect to the battery feed on the switch.
Excellent idea on the inverter/charger connection. I would save on footage and connect to the starting battery as well. Or would this cause problems being a differently sized battery?
This has been a complicated experience figuring panels needed, panel mounting, davit mounts, adjustable/nonadjustable, controller, performance and wiring.
Thanks for the sites and input to get me over my mental block. I will check them out.
Keep the info coming to assist others on the solar path. There is a 30% energy credit available (IRS form 5695).

 

[Bill Roosa]

think AC extension cord. 50-100' lengths, flexible, waterproof and CHEAP
Just neuter the ends for your needs