Pulling new solar wire using existing wire

[Monster1]

I bought a hemisphere 310bhi new this year that already had solar on it. It's basically just a battery maintainer since it's a single 50w panel wired to a 10A controller. I want to get rid of this inadequate set up and run a real system. My trailer is BIG and has about a 40+ foot run of wire from the rear of the trailer roof near the ladder to front of the trailer where the batteries are kept. From everything I've found, the wire the factory used is 14ga. I'd like to pull at least 10ga. Has anyone here pulled new wire through? How difficult? In theory it should be simple, but I have no idea if the wire has been secured anywhere along the run or if it makes an impossible bend anywhere. Last thing I'd need is to get the wire stuck moving forward or backward in the process of the pull. BTW, I'm aware that I have other options. But I want to use the existing wiring/location so I'm not drilling or creating more unnecessary holes.

Thanks

[Mike134]

If you're looking at 40' no way you'll get lucky using the old to pull in the new. Someplace is a staple holding it down or a right-angle turn.

On the slim chance I'm wrong use the old wire to pull in a clothesline if that goes thru then pull in the 10ga. If you get stuck cut it off flush, and use your alternate route

[Monster1]

Originally Posted by Mike134

If you're looking at 40' no way you'll get lucky using the old to pull in the new. Someplace is a staple holding it down or a right-angle turn.

On the slim chance I'm wrong use the old wire to pull in a clothesline if that goes thru then pull in the 10ga. If you get stuck cut it off flush, and use your alternate route

Yeah. I was kinda afraid of that. Here's other options

1. Using factory 14ga and running a 48v 400w single panel to a better controller. According to a voltage calculator, 400w at 48v on 14ga will only drop 3%. I'd have only one panel which would mean minimal holes on the roof and somewhat simple design. Panel would be permanent mounted flat so winter output would be decreased.


2. Leaving factory set up in place entirely and just running a portable set up on the ground. I already had bought two 100w panels and a controller for my last trailer before it had gotten stolen (these panels won't work for the roof top due to wire ga constraints unless I buy two more panels and run them in series at 48v. That's 4x the holes in the roof and double the real estate). So if I go with portable on the ground, I'd basically make a diy 200w suitcase and angle them as needed for maximum efficiency.

[corn18]

Take a look at your roof and see where your tank vents are. Really easy to remove the vent and run solar wire down along the outside of the vent. Mine came out in my basement and then I could run them forward to my solar charge controllers.

[TitanMike]

Originally Posted by Monster1

Yeah. I was kinda afraid of that. Here's other options

1. Using factory 14ga and running a 48v 400w single panel to a better controller. According to a voltage calculator, 400w at 48v on 14ga will only drop 3%. I'd have only one panel which would mean minimal holes on the roof and somewhat simple design. Panel would be permanent mounted flat so winter output would be decreased.


2. Leaving factory set up in place entirely and just running a portable set up on the ground. I already had bought two 100w panels and a controller for my last trailer before it had gotten stolen (these panels won't work for the roof top due to wire ga constraints unless I buy two more panels and run them in series at 48v. That's 4x the holes in the roof and double the real estate). So if I go with portable on the ground, I'd basically make a diy 200w suitcase and angle them as needed for maximum efficiency.

Going with a higher voltage panel makes a lot of sense. Remember one important thing about wire length in DC Systems (like solar). Wire length the TOTAL length of wire used for both positive and negative conductors. For example, if your panels are 40' away from the Controller, the length used in most charts (unless specified otherwise) wold be 80 feet.

As for a 200W DIY suitcase setup, that's what I have. Two 100 W panels wired in series and feeding a Victron MPPT Smart Solar Controller.

With the Bluetooth feature I can "adjust" the panels while watching the Solar panel output as well as the output current.

On a good "Solar Day" I have recorded as much as 1.2Kwh being "saved" in my LiFePo4 batteries. That's roughly 100 ah and even while I typically run a small freezer off an Inverter, watch DVD movies at night, and use my microwave up to 10 minutes per day, the portable solar system keeps the batteries well charged if the Sun is out full. Sure cuts generator time and often that's down to nothing.

[Monster1]

Originally Posted by corn18

Take a look at your roof and see where your tank vents are. Really easy to remove the vent and run solar wire down along the outside of the vent. Mine came out in my basement and then I could run them forward to my solar charge controllers.

When I pulled the service panel put to wire in a transfer switch and inverter, I noticed my holding tank vent pipes are right there as is the enormous hole cut from the factory to bring all the wiring into the coach. Everything is very accessible and o was ready to run my wires and bring them put the top of the trailer.

Unfortunately, I'd be dodging several pipe vents and both air conditioners. In the middle of the trailer is very cluttered both on the footprint layout and shadows. This wouldnt be good especially for a series wired system. The rear of the trailer is better for panel placement.

Maybe I got lucky though. I unscrewed the cheap waare brand controller and pulled the leads from the wall. It appears the leads coming in from the solar panel to the controller and from the controller to the battery bank are 10ga and have been spliced to fit into the controller with 14ga wires via wago connectors.

If that's the case, 10ga wire will be ample enough for a 400w panel pushing 48v. That will be enough solar power to keep my 200ah battery banks charged and happy with intermittent use of a 600w pure sine wave inverter used to watch TV and charge small electronics.

[richp]

To get my 600 watts from the roof to the controller near the batteries, I drilled a hole at the top of my black vent, and a somewhat larger one where it transited the storage bay at the bottom. Had my son in law push the new wire into the pipe from the top, and I snagged it as the loose end reached my hole at the bottom. Fed the wire over to the controller location, sealed both holes. Done.

Rich Phillips

[TowPro]

this is one system where I would recommend MPPT where you can run panels in series instead of parallel.


Series will raise the voltage which lets you push more power over smaller wire.


That is why the electric company pushes somethingt like 66,000 volts over distribution wires to the substations where it is reduced to lower usable voltage. Think of your MPPT controller as the sub-station

[Rolland]

Got this photo of the device used at the factory from Forest River on our 2021 Coachmen Sprit TT. I’d like to use the wires to pull a larger wire than the factory 10 gauge to het more than 300W on the roof but am doubtful they would pull through.

[Monster1]

Originally Posted by TowPro

this is one system where I would recommend MPPT where you can run panels in series instead of parallel.


Series will raise the voltage which lets you push more power over smaller wire.


That is why the electric company pushes somethingt like 66,000 volts over distribution wires to the substations where it is reduced to lower usable voltage. Think of your MPPT controller as the sub-station

That's what I intend to do. I had bought a bundled kit with a cheap Renogy wanderer 30A PWM controller when I was going to install it on another trailer that required a much shorter run. I'm going to buy a MPPT controller and wire the panels in series to increase the voltage and keep the current at 8.33A. The wiring that is currently in the trailer is acceptable for that application.

[W5CRE]

Originally Posted by Rolland

Got this photo of the device used at the factory from Forest River on our 2021 Coachmen Sprit TT. I’d like to use the wires to pull a larger wire than the factory 10 gauge to het more than 300W on the roof but am doubtful they would pull through.

10ga will handle 30amps. Why would you need larger wire? What size panels is this 300W? What are the Voc (open circuit voltage) and Isc (short circuit amps)? How you connect these panels will determine the combined voltage and current that will go through those wires. You could do many different arrays that will allow you to keep your amps below 30. For example you can take three 100watt panels connected in series connected in parallel with another three 100watt panels connected in series and only have under 70 volts at under 12 amps. No need to use larger wire.
I would then recommend you use a 100/50 MPPT charge controller.

[Monster1]

Originally Posted by TitanMike

Going with a higher voltage panel makes a lot of sense. Remember one important thing about wire length in DC Systems (like solar). Wire length the TOTAL length of wire used for both positive and negative conductors. For example, if your panels are 40' away from the Controller, the length used in most charts (unless specified otherwise) wold be 80 feet.

As for a 200W DIY suitcase setup, that's what I have. Two 100 W panels wired in series and feeding a Victron MPPT Smart Solar Controller.

With the Bluetooth feature I can "adjust" the panels while watching the Solar panel output as well as the output current.

On a good "Solar Day" I have recorded as much as 1.2Kwh being "saved" in my LiFePo4 batteries. That's roughly 100 ah and even while I typically run a small freezer off an Inverter, watch DVD movies at night, and use my microwave up to 10 minutes per day, the portable solar system keeps the batteries well charged if the Sun is out full. Sure cuts generator time and often that's down to nothing.

Yes. Most people forget when calculating wire ga size that they have to calculate the total length, not just the positive wire length. It's noted in most wire ga calculation charts I've seen. Fortunately the solar wire ga calculator I used accounts for both by asking for the run length (not total length) from the solar panels to the battery bank. What I also like about that calculator is that it will account for 12, 24 and 48v systems.

[Rolland]

Originally Posted by W5CRE

10ga will handle 30amps. Why would you need larger wire? What size panels is this 300W? What are the Voc (open circuit voltage) and Isc (short circuit amps)? How you connect these panels will determine the combined voltage and current that will go through those wires. You could do many different arrays that will allow you to keep your amps below 30. For example you can take three 100watt panels connected in series connected in parallel with another three 100watt panels connected in series and only have under 70 volts at under 12 amps. No need to use larger wire.
I would then recommend you use a 100/50 MPPT charge controller.

If I go with 300w I won’t change the wire size. There is enough room for 400w si would then change. No plans to wire them in series due to issues with shading.

[corn18]

Originally Posted by Rolland

If I go with 300w I won’t change the wire size. There is enough room for 400w si would then change. No plans to wire them in series due to issues with shading.

What is the Voc for the panels? You need to get at least 20V to the SCC to get it to charge the batteries (5V over bulk charge voltage which is usually 14.4V or 14.6V)

[Mike134]

Originally Posted by W5CRE

10ga will handle 30amps. Why would you need larger wire? What size panels is this 300W? What are the Voc (open circuit voltage) and Isc (short circuit amps)? How you connect these panels will determine the combined voltage and current that will go through those wires. You could do many different arrays that will allow you to keep your amps below 30. For example you can take three 100watt panels connected in series connected in parallel with another three 100watt panels connected in series and only have under 70 volts at under 12 amps. No need to use larger wire.
I would then recommend you use a 100/50 MPPT charge controller.

Just an FYI solar panels will only provide the same short circuit amps as their normal current output. Totally different from a utility power supply

[jimmoore13]

I confess I did not read all the replies. I may repeat someone else's advice.

Given the distance, I'd run #8 wire. What you see as 40 feet may well turn out to be 50 feet or more once you factor in all the bends and redirects.

Then the easiest way to run the wire is to go through the roof with a gland (your kit may already include one) down into a closet or pantry cabinet that's close to the panel array at the back of the RV. Install the charge controller in that cabinet wall - either inside the cabinet or flush mounted to be viewed from outside the cabinet. Then continue the wire run down through the floor and along the undercarriage to your battery bank. You can keep it simple by adding 1/4" crimp on eylets to the ends of the wires and just stacking the wires onto the battery terminals. Nothing fancy required.

#10 may be adequate for 30 amps, but when the distances add up, so does the resistance (loss). #8 wire is good insurance that the entire output of your solar panel array will make it to the battery bank...especially if you connect the panels in parallel...and from the charge controller onward, you're likely to have nearly 30 amps on a sunny day regardless.

Plastic push rivets and nylon cable guides can hold the wire to the coroplast underbelly without a lot of struggle. If you have exposed framing, you can attach the wire to the metal frame using self drilling screws (you'll need an impact driver for this, but everybody should have one anyway). I ran #8 along my frame from the battery bank back to a little 500 watt inverter. I ran the wire up through the floor into a cabinet space to connect to the inverter. Easy.

The best way to flush-mount a charge controller is with an ocillating saw. These make very precise cuts, don't damage the paneling, and they are a great addition to your tool kit if you don't have one already. A cheap corded one is fine for a few jobs here and there. I liked mine so much I replaced it with a cordless tool, but between the tool, battery and charger, it amounts to an investment unless you already have the batteries and charger.

Note that all links are illustrations, not recommendations. Choose your fasteners and tools to suit your situation.

[TowPro]

every chart I have seen says something like "feet one way for pair of wires". never needed to double the distance.

[Monster1]

Originally Posted by jimmoore13

I confess I did not read all the replies. I may repeat someone else's advice.

Given the distance, I'd run #8 wire. What you see as 40 feet may well turn out to be 50 feet or more once you factor in all the bends and redirects.

Then the easiest way to run the wire is to go through the roof with a gland (your kit may already include one) down into a closet or pantry cabinet that's close to the panel array at the back of the RV. Install the charge controller in that cabinet wall - either inside the cabinet or flush mounted to be viewed from outside the cabinet. Then continue the wire run down through the floor and along the undercarriage to your battery bank. You can keep it simple by adding 1/4" crimp on eylets to the ends of the wires and just stacking the wires onto the battery terminals. Nothing fancy required.

#10 may be adequate for 30 amps, but when the distances add up, so does the resistance (loss). #8 wire is good insurance that the entire output of your solar panel array will make it to the battery bank...especially if you connect the panels in parallel...and from the charge controller onward, you're likely to have nearly 30 amps on a sunny day regardless.

Plastic push rivets and nylon cable guides can hold the wire to the coroplast underbelly without a lot of struggle. If you have exposed framing, you can attach the wire to the metal frame using self drilling screws (you'll need an impact driver for this, but everybody should have one anyway). I ran #8 along my frame from the battery bank back to a little 500 watt inverter. I ran the wire up through the floor into a cabinet space to connect to the inverter. Easy.

The best way to flush-mount a charge controller is with an ocillating saw. These make very precise cuts, don't damage the paneling, and they are a great addition to your tool kit if you don't have one already. A cheap corded one is fine for a few jobs here and there. I liked mine so much I replaced it with a cordless tool, but between the tool, battery and charger, it amounts to an investment unless you already have the batteries and charger.

Note that all links are illustrations, not recommendations. Choose your fasteners and tools to suit your situation.

Simply pulling new wire is my issue. Hell, I'd pull 4ga if it was possible. I'm not going to be able to pull new wires. It's just too long of a run and I'm not going to chance getting half way through and not be able to go forward or backward. And I don't want to install a hardwired system over the top of this one. If I can't make the current wiring work to upgrade the system already in place, I'll build a portable suitcase.

But since I now know the wiring is 10ga, I can series the panels to 48v @8.33A to an MPPT controller in the locations already installed and not have my new trailer butchered in the process. The rear of the trailer is the ONLY logical mounting location for the panels. The entire roof is very busy with skylights, air conditioners, vent pipes, etc. The rear of the trailer is the only unobstructed area that allows good placement and no obstruction to the sun.

[Monster1]

Originally Posted by jimmoore13

I confess I did not read all the replies. I may repeat someone else's advice.

Given the distance, I'd run #8 wire. What you see as 40 feet may well turn out to be 50 feet or more once you factor in all the bends and redirects.

Then the easiest way to run the wire is to go through the roof with a gland (your kit may already include one) down into a closet or pantry cabinet that's close to the panel array at the back of the RV. Install the charge controller in that cabinet wall - either inside the cabinet or flush mounted to be viewed from outside the cabinet. Then continue the wire run down through the floor and along the undercarriage to your battery bank. You can keep it simple by adding 1/4" crimp on eylets to the ends of the wires and just stacking the wires onto the battery terminals. Nothing fancy required.

#10 may be adequate for 30 amps, but when the distances add up, so does the resistance (loss). #8 wire is good insurance that the entire output of your solar panel array will make it to the battery bank...especially if you connect the panels in parallel...and from the charge controller onward, you're likely to have nearly 30 amps on a sunny day regardless.

Plastic push rivets and nylon cable guides can hold the wire to the coroplast underbelly without a lot of struggle. If you have exposed framing, you can attach the wire to the metal frame using self drilling screws (you'll need an impact driver for this, but everybody should have one anyway). I ran #8 along my frame from the battery bank back to a little 500 watt inverter. I ran the wire up through the floor into a cabinet space to connect to the inverter. Easy.

The best way to flush-mount a charge controller is with an ocillating saw. These make very precise cuts, don't damage the paneling, and they are a great addition to your tool kit if you don't have one already. A cheap corded one is fine for a few jobs here and there. I liked mine so much I replaced it with a cordless tool, but between the tool, battery and charger, it amounts to an investment unless you already have the batteries and charger.

Note that all links are illustrations, not recommendations. Choose your fasteners and tools to suit your situation.

Simply pulling new wire is my issue. Hell, I'd pull 4ga if it was possible. I'm not going to be able to pull new wires. It's just too long of a run and I'm not going to chance getting half way through and not be able to go forward or backward. And I don't want to install a hardwired system over the top of this one. If I can't make the current wiring work to upgrade the system already in place, I'll build a portable suitcase.

But since I now know the wiring is 10ga, I can series four panels to 48v @8.33A to an MPPT controller in the locations already installed and not have my new trailer butchered in the process. The rear of the trailer is the ONLY logical mounting location for the panels. The entire roof is very busy with skylights, air conditioners, vent pipes, etc. The rear of the trailer is the only unobstructed area that allows good placement and no obstruction to the sun.

At this point, my plan of action is to install a new MPPT controller in the location the factory controller is located. It's a Bluetooth controller so I'm not worried about its location in the baggage compartment. I already have two 100w panels and I'm going to rail mount in the rear of the trailer to allow for expansion of two more panels in the future. I've allowed for a 50ft run in the calculations to determine necessary wire ga allowing for a 3% loss. If I'm running 200w at 8.3A then 10ga wire is sufficient. If I'm running 400w at 8.3A then 13ga wire is sufficient. I'm covered in both scenarios. Thank you for your help.