Adding an external Solar Panel Port

1991sb · September 2021

We're very happy with 2021 320S and how well the rooftop solar panel keeps our battery charged. But our 2021 320S did not get a port added for external solar panels and I'm sure we'll be taking trips that would benefit from that connector. In Tabarado this year, I raised the question about what would be needed to add the port. With great input from the more experienced travelers there I decided to tackle the addition. Here is a brief description of the process. CAUTION: This just adds a port directly attached to the battery. Any external solar panel will also need some controller to avoid overcharging or destroying your battery. First, see how your battery is currently connected:
The attached diagram & photo shows ours

Image: https://us.v-cdn.net/5021717/uploads/editor/3x/jj1v0fim56bm.jpg

It takes a 7/8" hole saw to make the a place to put the port.

Image: https://us.v-cdn.net/5021717/uploads/editor/o1/pwctuui1m7lq.jpg

Image: https://us.v-cdn.net/5021717/uploads/editor/0g/h3kc2c4zsot5.jpg

This came from Amazon and has a nearly 22" 10AWG wire pair so it allows a fair amount of slack between the tub wall and the battery connections.
Rather than try to strip the and solder in the wires from the existing controller, I added a 30A fuse to the hot (red) wire and attached it to the positive battery terminal just like the existing connections. The black wire connects to the negative battery terminal along with the white wires from/to the electric panel and rooftop solar panel Victron controller. As seen in the next photo and diagram

Image: https://us.v-cdn.net/5021717/uploads/editor/ts/x72d0byse40y.jpg

I look forward to getting an additional solar panel and trying everything out in the near future.
Bill

pthomas745 · September 2021

Very nicely done.

AnOldUR · September 2021

1991sb said:

I look forward to getting an additional solar panel and trying everything out in the near future.
Bill

Great job! If you haven’t yet purchased your solar panel, I suggest buying one without a controller and adding a Victron in your tub. Being closer to your battery increases controller efficiency and the Victron controllers can be networked. This is the setup I installed after reading recommendations here on the forum, so passing it along.

1991sb · September 2021

AnOldUR:
Thanks for the suggestion. Putting the controller in the tub would certainly change some of the wiring between the port and the battery.

AnOldUR · September 2021

Here's mine. The SAE port is on the right side of the box.

Image: https://us.v-cdn.net/5021717/uploads/editor/8j/0csh2uqegb52.jpg

Image: https://us.v-cdn.net/5021717/uploads/editor/ks/b2ffcmsb4p7n.jpg

Barbb · September 2021

My 2021 Tab 320S Boondocker has a port already for a second solar panel. Do I need a controller for that since it's already installed for use?

ChrisFix · September 2021

Barbb said:

My 2021 Tab 320S Boondocker has a port already for a second solar panel. Do I need a controller for that since it's already installed for use?

If you have a factory installed solar port installed, you'll need a solar charge controller to use with any solar panel you're hooking up through that port.
The factory installed solar port does not include a solar charge controller - it is just a direct connection to your batteries, and as such, a charge controller is required to connect a solar panel to the external port.

AnOldUR · September 2021

@Barbb, solar controllers are rated to meet the amperage from your solar panels. The controller nuCamp installs will not handle much more load than the factory installed rooftop panel. This makes sense because they can't anticipate how much additional solar someone may want. If the external port was wired through the onboard controller, the potential for overload would exist. You'll need a second controller rated to handle the output of your external panels. The suitcase style panels often have onboard controllers, but it's preferable to mount the second controller close to the battery to prevent voltage drop between the controller and the battery. If you use a Victron controller it can be networked with your existing controller for better performance.

Dutch061 · September 2021

@ChrisFix, I believe that ALL factory installations have a Solar Charge Controller, it is a must to convert the voltage from the Solar Panel and also control the charge rate.

Brad

ChrisFix · September 2021

Dutch061 said:

@ChrisFix, I believe that ALL factory installations have a Solar Charge Controller, it is a must to convert the voltage from the Solar Panel and also control the charge rate.

Brad

All roof top factory solar installations are connected to a solar charge controller. The currently installed factory unit is the Victron.

But it is my understanding that the factory installed external solar port is connected directly to the battery, and requires the use of either an external charge controller, or to have one installed to the external solar port wiring.

CharlieRN · September 2021

Barbb said:

My 2021 Tab 320S Boondocker has a port already for a second solar panel. Do I need a controller for that since it's already installed for use?

While the 320 BD comes with a 100 watt solar panel and BT enabled controller, as @AnOldUR points out, it unfortunately cannot handle additional solar panels. The controller is rated at 10 amps, close to the current output of the factory 100 watt panel (100 watts / 12 volts = 8.3 amps). In addition, as others have also pointed out, the second port is wired directly to the battery, and so using it requires that the input be via a controller.

While you can upgrade the factory controller or a higher capacity unit, keep in mind that you will then need to wire the auxiliary solar panel output to the controller. I found it easier and less expensive to simply add a second array with it's own controller, plugged in to the second port.

In my case, I went with a Renogy 100w Solar Suitcase array, and have been happy with its performance. In addition to the padded storage case, the kit comes with cabling, adjustable brackets that allow you position the panels for best performance and a controller. While the controller is the older PWM variety, it's performance is more than acceptable. I also added 30 feet of cabling that allows me to move the panels around to get the best position.

ChrisFix · September 2021

From a prior thread regarding adding an external solar port to my 2021 400 - the pictures in the thread linked below show the factory installed external solar port coming into the side wall of the 400 just below the shore power connection, and the roof top solar panel charge controller (Victron 75/15) with only one connection - which is to the roof top panel.
The external port is wired to the battery via the distribution block.

https://tab-rv.vanillacommunity.com/discussion/comment/172747/#Comment_172747

AnOldUR · September 2021

One thing to keep in mind if you're shopping for a Renogy solar suitcase. Renogy has a newer model, the Eclipse, that's a little more expensive, but smaller and lighter due to using more efficient technology. I ordered one specifically described as an Eclipse from Amazon, but was sent the older model by the seller. They did accept the return, but someone less knowledgeable could very easily be taken advantage of.

ReenieG · September 2021

I bought an Eco Worthy 120 watt solar panel that came with the controller and clips to charge a dead car battery. I figure it will double duty as an extra charge on my RV battery when boondocking. Is there any reason why this idea wouldn't work?

pthomas745 · September 2021

That will work just fine. Before I decoded the SAE Zamp Reverse Polarity Solar Port mystery, I used alligator clips for over a year on my panel. And, you can be the campground hero, since you can charge almost any car/rv battery with them, as long as you can get to the battery.

WayneW · September 2021

I went with a Renogy 100W solar suitcase with its own waterproof controller. As @AnOldUR pointed out, there are advantages to having the controller close to the battery but I preferred to stay with a stand alone panel. I can use it to charge my buddy’s bass boat trolling motor batteries or help someone out.

I have a 25’ cable wired with an SAE plug to hook directly to the tub without having to open it. I did have to install the SAE port in the tub myself even though the trailer is a 2021 320S Boondock. I can park the trailer in the shade and chase the sun with the suitcase. That, combined with the factory solar makes for a pretty flexible and relatively cheap solar package.

I also have a short pigtail with an SAE plug on one end and alligator clips on the other that I connect to the 25’ cable for charging other batteries.

ScottG · September 2021

I don't particularly like futzing with clamps, but I do like having them as an option. Like WayneW, I have a modular system that allows the use of either an SAE plug (to connect directly to the SAE port on the tub) or alligator clips (to connect directly to a battery).

I took a step further and even made my controller modular. Under normal use it sits in the tub at its optimal location near the battery, but it can also be attached directly to the panel for remote use as needed. This has the added advantage of keeping my controller--which is not waterproof--out of the elements and allows me to keep my panels deployed full time once in camp.

If you can make cables (not particularly hard to do) you can be creative in ways that optimize both performance and versatility.

K_C_915 · November 2021

Experienced Solar people,
No one has a problem with two controllers charging the same battery from two independent panels?
Since I am a retired electrical engineer I think too much.

I had trouble keeping my battery charged over three days and my need to add movable panels to my rig.
Thanks

Horigan · November 2021

Just make sure the voltage and battery type settings between the controllers are the same and you should be fine.

AnOldUR · November 2021

@K_C_915 ... On a suggestion found here on the forum, I purchased a Renogy suitcase without a controller and added a Victron 75|15 mounted in my tub. The controller that comes attached to the Renogy will work, but using a Victron gives you the ability to network the controllers so that they work together. You can also monitor them both with the Victron app. There are voltage drop advantages to having the controller close to the battery rather than mounted on the panel.

Sharon_is_SAM · November 2021

@K_C_915 - correct. The battery doesn’t care - just like having solar and a tow vehicle charging at the same time. I agree with AnOldUR. If you already have factory installed solar with the Victron controller, it is pretty seamless to use a second Victron controller with a portable panel. The Victron Connect app makes it easy.

ChrisFix · November 2021

@K_C_915
I can also verify that 2 Victron controllers work perfectly together. It's a great system in fact.
Here is a link to my second Victron and external solar port installation:
https://tab-rv.vanillacommunity.com/discussion/comment/173150#Comment_173150

Denny16 · November 2021

Nice job Chris, but why did you put the SAE connector on the Drivers side vs the passenger side, which is closer to,the battery distro block on the 400? My factory installed SAE is on the Pax side next to the storage locker door, which I find very convenient, as we deploy the panels on the Pax side.
Cheers

K_C_915 · November 2021

Thanks everyone for the advice.
So much to learn.
K&C

ChrisFix · November 2021

Denny16 said:

Nice job Chris, but why did you put the SAE connector on the Drivers side vs the passenger side, which is closer to,the battery distro block on the 400? My factory installed SAE is on the Pax side next to the storage locker door, which I find very convenient, as we deploy the panels on the Pax side.
Cheers

Because it is exactly where nuCamp is installing it on the 2021 and 2022 T@B 400. My early build 2021 didn't come with it...so I added it myself and wanted it to look factory.

ckjs · November 2021

K_C_915 said:

Experienced Solar people,
No one has a problem with two controllers charging the same battery from two independent panels?
Since I am a retired electrical engineer I think too much.

@K_C_915 , I resemble that remark! Another retired EE here:

I think that two parallel controllers would work okay.

However I don’t think that both are necessary.

I also want to add a portable panel and external port for shady-campsite situations. The external panel voltage is about the same as the rooftop one. The overthinker in me asks:

What is the point of a second MPPT controller in this situation?

It ought be safe to connect the ~20V from the portable panel in parallel to the rooftop panel, at the PV input of the Victron. It is just like one panel being shaded while the other is in the sun. That happens all the time without problems.

It would deliver slightly more power to the batteries, since the long wires to the external panel would run at a higher voltage and lower current, reducing the voltage drop by about 40% for these 20V panels.

It also means that you don’t have to buy another controller and waterproof housing.

What happens to the Victron if both rooftop and external panels are in the sun, e.g. potentially providing 20V at 15A? That 300 watts is more than my MPPT 75/15 can deliver. However, the controller limits its power draw to what it can handle, so in the both-in-the-sun situation the worst that happens is that ~100 watts of excess solar power are just not used. Nothing burns up.

(I found some confirmation on the web that then MPPT power limit protects the controller e.g.:
https://www.eevblog.com/forum/renewable-energy/over-dimensioning-a-pv-array-why-max-current-input-limit-for-mppt-chargers/ )

Granted, I would lose the ability carry the portable panel to another campsite’s and charge up their 12v batteries.

Given that I’ll bother to set out the portable panel only when our T@b is shaded, it seems a waste to have a second controller when, almost all the time, only one is needed.

What do you think?

Denny16 · November 2021

That works, having the portable SAE connector tied into the existing 75/15 controller, as long as you do not want the max solar charging of both panels outputting 300+ watts.

I wanted the ability to get more than 200 watts of solar charging, so I went with two 75/15 controllers, the TaB 193 watt panels connected to original controller, and my portable 200-watt panel setup connected to a second MPPT 75/15 to get 300-400 watts of solar charging.

Down the road, I would like to have 300 amps of lithium batteries and a 2,000 watt inverter to run the AC when I need it to cool off the camper, or run an induction cook top. Hum, an all electric TaB400…

K_C_915 · November 2021

AnOldUR
How did you mount the controller in your tub?
Need you need to put it in a water proof box?
I can see the tub getting water inside at time.

I am starting to lean to your solution.
Thanks
K&C

Denny16 · November 2021

You can mount the controller in the tub, there are several discussions showing this done. You do need a water splash protection, but not a completely enclosed box, just the sides, back and top, bottom hand have vent holes or be open, as well as the front area can have vent holes. The controller does need some air for cooling.
Cheers

bjn2 · February 24

Just a note that Victron recommends locating the controller near the battery, so if you've moved a LiFePo battery inside the trailer, you wouldn't want to put the Victron in the tub. I've mounted a Zamp solar port to the right side of our tub and connected it to the OEM solar wiring that used to go to the existing Victron controller. I'll extend those (now unused) wires so I can mount the new controller in the same bay as the battery.

Sunfellow · April 12

I have a T@B 2022 320-S Boondock. It has two Battle Born Lithium 100Ah 12V Deep Cycle LiFePO4 batteries. The factory-installed solar panel is wired to automatically recharge these batteries. I want to add 2 Jackery 100 watt solar panels that can be adjusted (moved around) to generate more energy while my T@B and factory-installed solar panel is in the shade. My T@B does not have a solar port/plug. Can anyone tell me how to install a solar plug/port so I can plug my 2 Jackery 100 watt solar panels into the lithium batteries?

Thanks for your help.

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