Wire size from Solar panels to the Charge Controller

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Toy4Rick

Senior Member
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Apr 13, 2021
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421
Hey all

I'm considering a solar upgrade to our 2022 2500RL. Currently have a single Furrion 165W panel going to a 300W Charge Controller (CC). The wire from the Furrion roof box down to the Charge Controller is 10AGW

Considering 2 - 200W Renogy panels wired to a Renogy 60AMP CC, down the road I may add 2 more panels and set them up as 2S2P

My questions are...
1. Is 8AGW required from the solar panels to the CC
2. If so, will MC4 connectors take 8AGW, I've only seen 10AGW and based on crimping on an MC4 today to 10AGW, don't see it working with 8AGW but I don't have any here to test with
3. If so, what is involved in pulling a new 8AGW from the roof to the water pump area in the pass through storage area where the CC is currently mounted.
It seems to be run up between the front cap and the bedroom headboard wall.
My guess is it's not stapled in place and once the roof box is removed, use the 10AGW as a pull line

Thoughts?
Thanks, Rick
 
You need to figure out what panels you will use. I had to use the Rich Solar 200w panels as their dimensions had a width that really fit well on my rig. In fact I put those same panels on my GD 2600rb for same reason. You will need to know the voltage of panel you will go with. A 12v panel will push twice the amperage thru the wire when compared to 24v panel; thats the second reason I went with this specific Rich Solar panel, they are 24v panels. Please don't confuse solar voltage with trailer voltage. The sole job of the MPPT box is to buffer between solar and battery. If this helps, I ran (4) of these Rich Solar panels down to basement (wired in series) using 10awg wire which is around 9amps. This is plenty of capacity to spare on 10awg. So to answer your questions: 1. 8awg is not required unless you use 12v panels or too many watts of solar. 2. MC4 are designed for 10awg. 3. Avoid running 8awg. 4. The 10awg is likely stapled (mine sure was); it was not usable as a drag line.

With all this said, a real true asset you have is Will Prowse. When you get a few thousand of spare hours to read/research/read, try THIS resource.
 
Toy4Rick said:
Hey all

I'm considering a solar upgrade to our 2022 2500RL. Currently have a single Furrion 165W panel going to a 300W Charge Controller (CC). The wire from the Furrion roof box down to the Charge Controller is 10AGW

Considering 2 - 200W Renogy panels wired to a Renogy 60AMP CC, down the road I may add 2 more panels and set them up as 2S2P

My questions are...
1. Is 8AGW required from the solar panels to the CC
2. If so, will MC4 connectors take 8AGW, I've only seen 10AGW and based on crimping on an MC4 today to 10AGW, don't see it working with 8AGW but I don't have any here to test with
3. If so, what is involved in pulling a new 8AGW from the roof to the water pump area in the pass through storage area where the CC is currently mounted.
It seems to be run up between the front cap and the bedroom headboard wall.
My guess is it's not stapled in place and once the roof box is removed, use the 10AGW as a pull line

Thoughts?
Thanks, Rick
Click to expand...

Don't think you need/want 8 gauge. 10 gauge can handle about 30 Amps safely (less if the leads are long). Your two 200 W panels are about 33 Amps in theory, but you'd rarely get the full output in practice (400/12=33). A 2S2P for 4 panels would be the same amperage (800/24=33). I'm not sure if the Renogy charge controller is set up to handle 24 volts though, you might want a different model.

Converting to 8 gauge would not (in my opinion) be a trivial exercise. I doubt if it would be as easy as pulling the 8 gauge though using the existing 10 gauge. And no, as far as I know, you can't use MC4 connectors with 8 gauge, you'd probably need some collector box on the roof to tie in the panels.
 
It depends on the panel amperage and voltage output and if you wired in series or parallel. Series voltage doubles but amperage stays the same. Parallel Amperage doubles with Voltage the same. Each way has its benefits. 10awg will handle most installations. Will Prose has some good information https://www.youtube.com/@WillProwse

Things to check
Will your solar controller handle 8 awg Most wont. The larger Victron units I believe will.

Will you solar controller handle all the panels you planning on. If not now is the time to upgrade. I would recommend a Victron MPPT controller capable of your current and future needs. They have Bluetooth so you can see what going on. Also check the solar controllers max panel size based on wattage.

What is the distance from the panel to your solar controller? This site is great for proper wire sizing.
https://www.bluesea.com/support/art...oosing_the_Correct_Wire_Size_for_a_DC_Circuit

8awg MC4 Connectors are available Just Google " 8awg MC4 connectors " Here are some on Amazon
You will need a crimping tool that is for 8awg fittings though. A poorly crimped fitting can cause issues. Here are some on Amazon https://www.amazon.com/s?k=mc4+conn...493520&tag=googhydr-20&ref=pd_sl_6qomg3i1dp_e

Windy nation has pre-made sets too https://www.windynation.com/search?q=8+Gauge+(AWG)+Solar+Panel+Cable+&options[prefix]=last If it was me this is the way I would go. They also have great customer support and can probably help you find out if you solar controller can handle the panels you want.

You may need to change out your roof box, so double check its not the Furrion plugs. The look like MC4 but are not compatible with them.

Hope this helps
 
powerscol said:
8awg MC4 Connectors are available Just Google " 8awg MC4 connectors " Here are some on Amazon
Click to expand...

Put this in the "you learn something new every day" category. Would the MC4 connectors on a prebuilt 8 gauge cable connect with the standard MC4 connectors that are generally used with 10 gauge cables?
 
Last edited:
powerscol said:
They should, but best to call and ask. GD did use Furrioun roof boxes for a while. If you have one I am pretty sure the std MC4 will NOT work. Lots of threads on the issue. Most folk just replaced the roof box with a std MC4 one

I just searched will 8awg MC4 connectors work with 10 awg MC4 connectors
https://www.google.com/search?clien...C4+connectors+work+with+10+awg+MC4+connectors

Shore answer is yes.
Click to expand...

Douh - LMGTFY:D

Now about the Furrion connectors which I have. I'm planning to upgrade my panels this spring. I planned to cut the cable from the existing box to the panel and splice on some MC4 connectors. But now you have me rethinking that. What would be the advantage of changing the box? It seems like more work than working with the existing cables.
 
When Dylon was ready to replace my connector box with a new one to handle multiple panels he found that GD put a huge hole in the roof for the 10 GA wire. The hole was covered by the box, though, so no leak issues. He then decided to put the new box next to the existing one and run a pair of wires from the new to the old. Then he found that GD used a different connector, so he ended up cutting the connectors off of the old solar panel and connecting them to the new wire. Lots of extra work.
 
Hey all

Yes my current solar panel has the Furrion proprietary connectors and I found out today by calling Lippert, they have replacement ends so if yours are broken like mine, you can replace them without changing out to MC4 and changing the roof box...

As for my project, yes 2S2P is doable with the Renogy MPPT charge controller from what I am reading, more research is needed. Currently I'm just considering 2 panels so it's not something I have to work out at this time.

Good to know that 10AGW from the roof down to the CC is sufficient, I will need to ensure the wires from the CC to the battery are sized properly, my guess is they will need to be changed out

Thanks for all the great info
Happy trails

Lippert part number for the Solar connectors is 2022009862
 
Toy4Rick said:
Hey all

Yes my current solar panel has the Furrion proprietary connectors and I found out today by calling Lippert, they have replacement ends so if yours are broken like mine, you can replace them without changing out to MC4 and changing the roof box...

As for my project, yes 2S2P is doable with the Renogy MPPT charge controller from what I am reading, more research is needed. Currently I'm just considering 2 panels so it's not something I have to work out at this time.

Good to know that 10AGW from the roof down to the CC is sufficient, I will need to ensure the wires from the CC to the battery are sized properly, my guess is they will need to be changed out

Thanks for all the great info
Happy trails

Lippert part number for the Solar connectors is 2022009862
Click to expand...

I found these connectors, were they what you used?
 
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