Solar

[Southpaw]

I’m in the process of putting solar on our boat. So far I bought 4 180w grape solar panels, 2 Victron MMPT 75/15 smart controllers, Victron MMPT 100/20 smart controller and a Blue Sea 5025 fuse block. The plan is to put one panel on each side of the boom on the Bimini and two in series over the dingy on the davits. What size wire should I get and what type of fitting for the wire to feed through the fiberglass? I was looking at the ancor 10/2 duplex Marine.

 

[Sumner]

Since we don't know the length of the runs from the panels to the controllers and on to the batteries it would be hard to tell you what size wire to use. I use a wire size calculator like this myself...

https://www.colemanair.us/vp_asp/Scripts/Articles/TheBasicsAndBeyond5_WireSize.htm

You should consider the length of the run all the way from the panels to the batteries and size the wire on the voltage drop you find acceptable. The less the better and I've kept mine under 2%.

I ran my wire from the panels down into the boat in flexible conduit. More on the install here ....

http://1fatgmc.com/boat/end-1/endeavour-elect/page-7.html

Sumner
=========================================================================
1300 miles to The Bahamas and Back in the Mac...
Endeavour 37 Mods...
MacGregor 26-S Mods...http://purplesagetradingpost.com/sumner/endeavour-main/endeavour-index.html
Mac Trips to Utah, Idaho, Wyoming, Canada, Florida, Bahamas

 

[dlochner]

You should consider the length of the run all the way from the panels to the batteries and size the wire on the voltage drop you find acceptable. The less the better and I've kept mine under 2%.

With DC current, it is necessary to consider the distance from the power source (solar panel) to the battery and back again. If the one way distance is 10 feet, the roundtrip is 20 feet and the wire should be sized for a 20 foot run.

 

[Sumner]

With DC current, it is necessary to consider the distance from the power source (solar panel) to the battery and back again. If the one way distance is 10 feet, the roundtrip is 20 feet and the wire should be sized for a 20 foot run.

Yep and that calculator I posted takes that into account even though they ask for just the one way distance.

Sumner
======================================================
1300 miles to The Bahamas and Back in the Mac...
Endeavour 37 Mods...
MacGregor 26-S Mods...http://purplesagetradingpost.com/sumner/endeavour-main/endeavour-index.html
Mac Trips to Utah, Idaho, Wyoming, Canada, Florida, Bahamas

 

[Southpaw]

I will go down to the boat to estimated the distance. All of the solar panels come with mc4 connectors and the largest size wire is # 10 that can be used with the mc4 connectors from what I can see.

 

[Stu Jackson]

All of the solar panels come with mc4 connectors and the largest size wire is # 10 that can be used with the mc4 connectors from what I can see.

Yes, that may be. But if your distance requires larger size wire, then you will need to do a short piece of #10 and then the larger wire. You can splice or put in a terminal strip.
Just about every solar website includes wire sizing and details you need to respond to your original question.

 

[capta]

If clear of any obstructions, your panels will put out nearly full power, at least for some of the day, down in the BVI. Therefore, you must rate the wire for that amperage, even though your daily average will be considerably less than that. However, your power is split 3 ways, so each feed may not be all that much amperage. 10ga may do fine, just use good quality tinned boat cable.
Also, I had to install my panels in a hurry and just bolted them to the Bimini bars with a spacer so air can circulate under them for cooling. When I have time, I plan to build 2 bars that go athwartships close over the Bimini, from bars I already have for handholds going fore and aft on the sides, to remount the panels on. This is a much better system because right now I cannot take my Bimini apart w/o removing the panels.