How to Choose Solar Panel Wire Size in a DIY Camper Electrical System 

Thank you so much for making these videos! They are so helpful.

Great Videos Nate. I use your video series as a reference before doing my work on my Solar

The way you explained this made it easy to understand. Thank you

Thank you Nate for all this great information here and on your site. I'm knee deep in version.3 solar retrofit/upgrade system for my T1 and you have addressed both technical and practical information for an awesome, safe, powerful, and trouble free system for years to come. Happiness is better burrito defrosting, longer binge watching of Game of Thrones and no more policing lights left on during extended boondocking. It's going to be a great summer.

Thanks again Nate for your helpful info, I will be in touch when I am ready with my cargo trailer build.

Thanks for your great advice. Really appreciate it.

Nice job on video series. I tried to use the wire size calculator and was unable to have it calculate. Thanks for your dedication Scott

Very Educational & thorough ! But I’m a DIYer doing this for my home ! I have to figure out how to pull up all you’re last videos like and share !

Very helpful and I’m glad you set up the calculator. Thank you so much!

I have looked into this for a long time for my 24v setup this really helps

very clear tutorial

Awesome!!! I just got a small 400 watt array done yesterday. Found your video this am. At least I did NOT under cut the wire size & fudge the distance between array panels & controller!!! Thanks for the information!!!

Thank you!

I'm an electrical mechanic, but it's been awhile. Your videos are very well made IMHO and are an excellent resource for novices (and a useful refresher for old hands). BTW You realise that somewhere, someone has taken a "7.5kw solar van" as a challenge, don't you? 🙂

This video helped a newbie like myself (i think?) better understand how to setup two 100W panels in parallel as I believe series is not what I want since I do not want to increase voltage. The diagram also helped with understanding that I need a combiner to do this. I'm very green with solar, but feel like I got the bug and can't stop wanting and needing more since I started so small when I want a sustainable amount of power for the basics and not just a few watts of charging power that is useless for reliability. I almost made the mistake of buying premade wires until I seen a simple it is to make your own and I don't think anyone should have buy premade. Thank you for your comment on the other video and your prices are fantastic and finally someone who offers more than 25 feet.

Thanks dude, good stuff.

A few months ago while installing a DC to DC charger in our new to us 2011 Airstream I discovered that there were 2-10 gauge wires labeled “Solar.” Of course I was delighted. When I started researching to find out where the other end of them is (behind the fantastic fan trim near the front) I saw several comments (incorrectly) complaining that the factory installed wires weren’t actually big enough to use. Now I’m actually in the process of installing solar (lithium, and multiplus) and those pre installed wires are a pretty big deal to me. Your videos and response to comments have been extremely helpful - so thanks for that.

Good

Good tips.

Awesome videos man. Do you select the wire gauge size coming out of the mppt to distribution block based on the highest amps that particular mppt can output?

Thanks. Like #14. In your example you get 8 AWG

Thanks Nate extremely very informative video's I'm watching every video that is from you. My question to you is I'm installing 6x100W planning to add 10x100W if roof space don't allow I will stay with 8x100W with 2x30A eco worthy charge controllers. Is it safe to run all panels to one charger or is it better to split the panels in to 2 chargers groups and run with a 10AWG I also have a perfect suitor 70A not sure if I should run in paralel or in series.the set up is with 7x100A lead acid deep cycle running a mini fridge a lap top and a laser printer TV, Your expert opinion is much appreciated Alex

Thank you for this clear video! Do we look at the vmp of voc of a panel? Can we do a 1% voltage drop before and a 2% voltage drop behind a combiner? Thanks in advance.

I am an electronics technician and agree that the 10awg is the default wire gauge to use to bring power from the solar array to the charge controller. Knowing the distance from the solar array to the charge controller is important in determining how many panels are needed and how to connect each panel together. Good video Nate.👍

I recently found your videos and really enjoy them. Have you done a video on a good way to conceal the solar wiring and particularly, the MC4 connectors? I'm considering some flex tape and dicor or even a junction box.

No problem

You have a talent 🤓

Once again a great shot video. Question? When determining voltage should I use the Voc or the Vmp? Thank you

I absolutely love watching your videos since I still learning about solar. I have a new Genesis Supreme toy hauler and I have upgrade to lithium batteries. Now I have started upgrading to more panels. It has one Go Power 190w 12v panel. I am adding 3 more Eco Worthy 195w 12v panels. Current wire size is 10 gauge from the panels to CC and 10 gauge to the battery's. I am ditching the go power 30 amp charge controller and getting a victron and placing it in the battery compartment. Right now I am wired in parallel. That is to much for 10 gauge so if I run it in series it should be OK right? It's about 30' run maybe shorter. Also I did get a victron MPPT 100/50 but I probably should of got a 150/60. Any input would help thank you.

Hey there awesome video as always. I ordered 36 cells from Alibaba and only 28 cells arrived. Looks like the last 8 cells will not be arriving. My question I planned on doing two 16S 2parrell banks creating 48 volts system. Can I still so this with 28 battery's ? Like add a set of three cells in parallel then add a set of two in parallel and continue to add up to 48 volts ?I was hoping to be able to use all 28 cells as each one is 280AMH

Thank you for the calculator. What formula do I use to figure out how many amps my 1500w 24v inverter use? Your calculator ask for amps.

Hi Nate. Excellent video thanks. I have a caravan come with 2 x 100W solar 19v x 5.26A parallel wired. Have them running to a Renogy 40 Charge controller to 2 x 125AH lifepo4 batteries in parallel. I want to add 2x 300W panels to caravan roof. These panels are 19v 15.7A panels. Can I do this and how should I? Do I need another controller? How to I get this power to the batteries please? The batteries have an individual recommended 30A charge rate but can charge at 60A. Appreciate your help. I am on the pension so funds are limited. I was given the new panels as a gift. Kind wishes Wayne from South Australia.

But what about the wire size from the mppt to battery? That's what I was hoping to find out

Nice video ❤❤❤❤ i have 48V solar charger controller 30A ok what size solar panel to used how 12Volt panel i need am in Toronto Canada i have 3000 watts pure sine wave 48V inverter

I have two identical panels and I have the option of being able to tilt one towards the sun to improve its efficiency. Will this be worth it or will it cause problems having one panel working at a higher efficiency than the other?

Hello Nate, I am somewhat cofused , most of the videos I see have a very long solar panel run of 75 ,100 ft using 10awg, I spec my array out to 8awg using 4 x 300 watt panels =1200watts at 50 ft with 10-15 amps line feed for a lower voltage drop. to the controller.Are my caculations valid.

How critical is the 1.5% Voltage drop? I have 4 panels and was going to wire them in series/ parallel. At 40.9V and 10.65A each, the difference between 1.5% Voltage drop and 2% is the difference between 8 gauge wire and 10 gauge (already installed by manufacturer)

Great video. I have a 100 foot run from my solar array to my charge controller. I'm using 10AWG wire for the run. The calculator recommends 4AWG wire to keep the voltage drop lower. To save money, could I parallel another set of 10 AWG wires with the original wires to get a lower power loss, or is that a non standard practice ?

Hi trying to optimise my solar charging. I'm now going to have to watch all your videos 😂. No bad thing. Question. 10awg is that for each, ie negative is 10awg and positive is 10 awg. I have seen wires that are double core purporting to be 10awg, but actually I'm confused as maybe the size of the 2 wires combined make 10awg. Surely this would mean a large voltage drop

Quick question, can you install 5 100w in series and then parallel two sets of 5 panels for total 1000 watts? If that makes sense

Hi Nate do you think you can cover settings for Victron components? Especially the complex ones like the Cerbo GX and VEConfigure. Videos for those with your quality are non existent. Youd have a monopoly

Hey Nate, looking to buy some solar wire from you. But I'm needing to find out the outter diameter of the conduit as I have specific clips I'll be using on my 80/20 solar rack. Thanks Nate!

What about from the controller to the battery?? Here the amperage will be much higher as its effectively going to be the amount of amps charging the battery from all the combined power of the solar panels?

I have a solar panel of 150w , 20A controller ,300w min to 600w max inverter and a battery of 200A. But it is not working well. What size of the wire should I use for it work well??

I have watched all of your videos and have learned a lot from them….Thank you. I have a question concerning the rich solar kit that is listed on their sight. I am looking at the 800 watt solar kit with the 40 amp mppt. I called them and they said it will work but the numbers don’t add up. I know that they are using the 200 watt solar panel VMP of 20.4 and the imp at 9.80 amps. The kit diagram has it running in series so that means 81.6 volts and 9.80 amps. If the batteries are being charged at 14.6 volts would that mean that the mppt solar controller will be producing almost 55 amps to the batteries? If this is the case then this is over the 40 amp limit for the solar controller. Am I right with this or am I missing something?

Something puzzling has come up. I have 24-volt, 200 watt panels. 3 panels in series would be 72 volts but the rating on the panel's sticker has a 45-volt output! So which voltage would I wire for 72 volts or 135 volts?

What?! I agree, if someone has a 7500w solar setup of their camper, I too would like to see that, due too that's like roughly 75 solar panels(assuming they're using 100w 5amp panels)to get 30amps at 250 volts(which in its self is hard to figure out how they got it in both parallel and series to match)

I am in the process of upgrading the electrical system in my toy hauler and because my space is limited I would like to install my lithium batteries and charger converter\Inverter underneath the bed. My concern is the heat build up, can you discuss that in a video please?

Can 10 awg wire carry 35 amps in a two foot run?

I just had to watch this one .... yep 10ga wire your done ! LOL ! Love the why you gave though ! I'm still laughing !

Good Morning. I have two Battle Born Batteries and a 2,000 Watt inverter. I would like to install some Solar panels on the roof. One to maintain the batteries and some recharging when I boondock for short times. What do you think would be a good wattage on the roof and how many would be best for this. I have a 5th wheel trailer 2019 GD 337RLS. Thank you Jack

Hey there I was just wondering can I use an old extension cord to convert to solar panel cable? It's the middle of winter here and the sun is not very powerful and I'm running a 265 Watt panel.

Thanks so much for all the helpfull videos. That '20 volt above battery voltage', is that the open circuit voltage or the max power voltage?

Hey Nate. Is this 10 awg wire a solar specific wire or can you use a standard 10 awg stranded wire from the hardware store?

First, thank you so much for your clear explanation! May you help me on how to calculate the the usable load in Watts that keeps the solar arrays charge the battery (lithium batteries) while is being discharged. For example, I have 400W , 12V solar arrays, 300 Ah lithium battery pack, with 500W sine wave. How many Watts load can I draw from this system that can keep my battery being charged while being discharged. Thank you!

I put up 4-210 watt panels and thinking I'll be wiring them two in series then paralleling the 2 series, i only have 6 feet across the roof and 2-3 feet down to charge controller. I was wondering if i could just run one sized wire so i wouldn't have to buy different sizes so thanks for mentioning that bigger is better. Your calculator suggested 12 awg and 30a in line fuse, but i will be running a 15a inline fuse on the series before paralleling. Am i correct i wont need any more going to the 60a charge controller after paralleling? My open circuit voltage is 19.83v and short circuit current is 13.09a, i am thinking about getting red and black 25 foot rolls of 10awg which will be 5-6 foot more than I'll use all the way to my batteries. I'll be ordering from amazon, i didn't look yet but do you have a link to purchase the wires and connectors thru?

Hey! I have (4) 175 watt renogy panels and they come with 12 awg wire connected to each panel. How do I connect all my panels with 10 awg if they all start with 12?

*Request:* I know you use 20 volts/5 Amps for simplicity but it really makes it hard when I personally look at solar panel data sheets. For example 100w 12v Renogy states voltage for Operating Voltage (Vmp) @ 18.6v and Open Circuit (Voc) @ 22.3v so one is below and the other is above 20v. At least Amperage for this model are both 5.x. *But does that mean I should round up or down for amperage?* Unfortunately the system I am building requires Solar in Parallel because I am using an "all in one" system for a MPPT charge controller. So getting the Amp's accurate is crucial for wiring after the connector. I know I have a consultation fee in my future (so many "little" questions about my specific installation) but trying to get a complete grasp of the "easier" stuff like this is critical.

Hi Nate, Great video! Just discovered your video. Would love to collect the series from video volume #1. Would you send me the link? Thanks in advance!

I have mppt all in one inverter 2400, my solar panel is 2x rich solar 200w 24v connected as a parallel, my (Voc) 45.4v and (Isc) 5.83x2= 11.66, I'm currently using 8 gauge is it a bad idea using a little bigger on the size? But I only get 255w to 265w and 5a to 7a in a UV INDEX: High around 98f to 100f. Not sure if the issue was the 8 gauge that's why it doesn't get the full potential of my solar panel

I have spent over 10 hours doing research for my solar setup and I'm still confused. I have 2x 370w, 45.69 Voc, 10.30 Isc, using an online calculator it says 52amp at 102v. I used your wire calculator and it recommended 10awg. Is that correct? If I go off of what amperage wire can handle in general I need 8awg wire. I want to eventually scale up to 8x 370w panels for a 48v battery. Which would be wired in 2 series and 4 parallel. The calculator says 52amps at 102v also. Also what gauge wire can I use from the panels to the series connector? Obviously the wire from the series/parallel to mppt will need to he either 10awg or 8awg. My panels are pretty high voltage so my options are pretty limited as I have a 140/60 mppt controller. I have the renogy 60amp mppt controller and renogy 3000w inverter/charger. Also at the moment I have only one 12v 100ah litime group 24 lifepo4 battery. I intend to add 3 more and wire them in series for 48v. But that probably won't happen for a good 5 years or so. This system is intended for emergency situations/off grid power for basic needs. Water, lights, refrigeration etc. From my research the mc4 connectors cannot exceed 30amp and I need 52 (that is with the 1.25x for code) so then my only option would be combiner box but they are pretty expensive. For the 12v system with just the two 370w panels I can just wire them in series at 52amps 102v, then later on add the other panels in parallel for 48v. My gut tells me I need 8awg or 6awg directly from the panels to the mppt charge controller. Please help me!

Hey! How do i lengthen my cables from solar panels, to the disconnect switch? They just barely come thru my ceiling..

10awg is plenty for 960 watts then? I have 4 , 240 watt panels wired in parallel, running about 40'. I am very new to this, Thank you.

I guess the only time for 8 gauge would be just a very long run, like if you want camp in the shade and have your portable solar cells say 60 to 100 ft away out in a Medow or open area.

1 panel might gain 5amps under perfect conditions on the perfect angle. I've rated my panels at 75% of 5 amps and the wiring and the solar controller. My panels are flat on my van roof.😀

I have 2 300w solar panels, what size controller do I need?

Is there any electromagnetic risk when using solar like living next to high voltage power lines?

Can 40 amp charge controller able to handle 3x 200 watts worth of panels with a 30 amp fuse on the panel side. It would be a 12v setup.

I'm enjoying your video however I have my volume all the way up and I can hardly hear you maybe you can make some adjustments on your end thank you keep the videos going

Quick question for you, since all solar branch connector cables are all rated for 30 amps or so (10-12 gauge), if I wanted 500 watts of solar (42 amps @ 12v), should I try to make my own branch connector cable? Because I can't find any 8 gauge branch connectors anywhere on the internet at all. Or, should I just find some way to do a combiner box instead (although that might be hard because I am really limited on space).

7500 watts , maybe panels on the pull outs , mounted on the sides , back , front and a array trailer ! LOL !

Hi I think the app is giving wrong data please check. 20A, 562.5V, 46feet x 2 = 92 feet It's giving answer as 14Awg but 14awg can't handle 20Amps it can only handle 5.9Amps as per the amp chart.

Thanks, your videos are great BUT can you talk slower for us older people?😄

@6:12 you say "Boost the voltage, and lower the array amperage" I wanna install 5x365w (33,9V/10,6A) panels on my boat. The experts I meet on the jetty all say: on boats we put panels in parallel. But seeing your video's I guess you are more an expert than these boaties. The more the distance between panels and Victron Quattro 5k/120, is at least (via, via, via, via as it goes on boats -and RV's) 20meters. So, what would you advice? Put all the panels in parallel, with the mppt close to them, en then wire propperly the 20meters to the Q, or what?

How about metric units so that anyone outside US can use this without converting feet to meter and AWG to square millimeter. Other than that: great work.

Aha, 10 gauge wire.. means nothing to me. You should always mention metric sizes. People in other countries watch this too. mm2 please. Everyone should be using the metric system That's why mppt charger controllers that take string voltages up to 500v are better. Don't have to worry about parallel panels, combiners and fuses everywhere.. I have a big roll of 6mm2 wire. Most mc4 connectors I have are 40amp and some 60amp

Ugh.. more confused now

Wrong! 4/0 for the whole system. 🤣 kidding of course, 3/0 is enough.