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How Our RV Solar Power System Works: A Detailed Explanation

Many homeowners and RVers like us have been using solar power for years. Solar photovoltaic arrays allow you to take all that free energy that falls on your roof every day and turn it into usable electricity. Solar power technology is well advanced and available now to everyone. For more than half the year, we rely on power exclusively from our off-grid RV solar power system, and it runs everything just like we were plugged into the grid.   

In this article, we are going to break down the ultimate solar power system that we installed on our fifth wheel into bite-size chunks that everyone can understand.

We dove into RV solar energy with a cost-effective power system to see how we liked it, and we have fallen in love with its silent generation that enables us to easily live wherever we want as we are the power plant. ​

This was at the start of building the first system with 1100 Watts of residential 72 cell glass solar panels.

Check out our previous solar power system! 

PART 1: Installing RV Solar Panels

PART 2: Installing a Tesla Battery Module

PART 3: Installing the Inverter 

We decided to take our solar electricity to the next level.

We’re squeezed out as much power as we can get off this 33-foot RV with the latest technology and try some things with an off-grid system we never thought possible.  Join us as we build our Ultimate Off-Grid RV Solar System!

WATCH THE VIDEO:

Ultimate RV Off-Grid Solar System Build - 2760 Watts of Solar ☀️ 11Kwh Battery, on a 32' Fifth wheel

RV Electrical System Upgrade

With Tom being an electrical engineer and a do-it-yourselfer, he designed and built the whole system himself, so we had no labor costs for the installation of both systems. Tom has built dozens of grid RV solar systems for others, so this was an opportunity to build our own dream system.

We completely replaced the previous system with upgraded technology for this build.

​RV solar systems may seem complex, but if you break it down, off-grid solar systems consist only of a few major components. In this article, we will cover an overview of the components; you can check out the full schematic below. Don’t let this overwhelm you, however, as we will break it all down into understandable bite-size chunks.

Ok, here’s the bite-sized chunks! This diagram is the same as the schematic drawn out in a simple form. Lets take a look at each part to understand further how they work.

The Batteries

At the heart of every off-grid RV solar power system is the battery, which stores the energy for nighttime and cloudy day use. (Every RV solar system is essentially an RV solar battery charger.) We installed a much larger battery bank, 8 Battle Born 12V 100Ah GC2 Lithium-ion batteries. ​​

Our first RV solar system was built with a Tesla Model S car battery at its heart.   This worked very well but was a complex build as Tom had to design the whole battery management system himself to make sure the battery was safe. 

Tesla modules are a lithium NCA chemistry and pack a lot of energy into very little weight, but have the drawback that if anything gets out of spec with the battery they are prone to catch fire.

Lithium Batteries For RVs

While we had built a safe system and never had problems, it was much easier to install Battle Born Batteries for the upgrade. These batteries have all the protections built in so they can be hooked up like normal batteries. They also use Lithium Iron chemistry, which is inherently much more stable (at the expense of being heavier and slightly less energy-dense).

Regardless of this, these batteries still provide the massive benefits you get from lithium, and we firmly believe solar power systems need lithium batteries, to truly work their best. We also already had 5 batteries from our previous project, the Go North Expedition and this was a perfect opportunity to use them.


The Tesla module is on the right and Battle Born is on the left, a few cells of what is in the Battle Born battery sit in front of it.

One of the biggest benefits of lithium batteries is that they can be installed anywhere in any direction. For this build, we decided to install them upside down. Years ago we had removed the black tank from our RV  and installed a composting toilet.  When we did that we were thinking that we might use the space where the black tank was for batteries in the future, so that’s exactly what we decided to do. 

The Battle Born Batteries all hung upside down on where the black tank used to be.

We built custom brackets to hang the batteries upside down where the black tank used to be and wired them all up with the terminals facing down. 

Voltage Selection

We wired them in a 24-Volt configuration because with the amount of solar we would be installing, we needed a higher voltage system to handle the current. With larger systems (above 2500 watts), we always recommend building at least a 24-volt setup and possibly even a 48-volt. ​

By increasing the voltage from 12V to 24V the current in the system halfs and wire size can drop. This also increases efficiency in higher power applications and is why the power grid operates at such high voltages.


Batteries are all wired up upside down and ready to be connected to equipment

The RV Solar Panels

The solar panels generate power from the sunlight that is used to charge the batteries. In this build, we are going to use the latest tech mobile application solar panels to more than double our power production from our first build.

When we were starting to think about a solar upgrade, we decided to try out a panel that is a little bit less common. We chose to use Merlin Flexible Solar Panels. Battle Born Batteries sold these panels for a time but their cost made them less attractive. Cost, however, was not a major concern with this project as we were trying to maximize output with minimal weight.

We decided to install 230-watt panels that come in two shapes and sizes.

Tom holding one of the BBS230B panels prior to installation

We installed 10 panels on the roof of the RV, and because of the cool peel-and-stick design, we also decided to install 2 more panels on the front cap of the RV! 

The panels on the front cap won’t perform as well as the roof solar most of the year but come wintertime is where they really start pulling their weight. As a full-time RVer, we use our RV year round and solar always struggles in the low sun angles and short days of winter. Continue reading to find out how they have performed!

Pro Tip: We crunched the numbers to uncover How Much Do Solar Panels Weigh?

giant off grid RV solar power system aerial view


All 10 Panels on the rooftop, the 4 BBS230A are on the left and the 6 BBS230B are on the right.

rv with solar panels on front
Two additional panels were installed on the front cap of the fifth wheel.

What Makes These RV Solar Panels Special?

This is a rendering of the structure of these cells. The grid has a wave-like design both on the cell and on the connections to other cells that allows for flexibility. It also achieves very high contact and minimizes series voltage drop.

These panels are unique because they are high-efficiency mono-crystalline cells in a flexible stick-down package. These panels are 19% efficient vs. our previous panels’ 14% efficiency, meaning we get more power out of the same space! This is especially great when you’re working with limited space – like an RV roof.

Flexible RV Solar Panels?

In the past, we have been leary of flexible panels because they tend to have short lives due to thermochemical stresses internal to the panels, but these panels have solved that. **While we chose these for this build we are not sales reps or have any affiliation with Merlin, this section is purely because this tech is interesting and serves a specific purpose.

The Merlin Solar Panels utilize a special grid structure instead of bus bars that allow for considerable movement without breaking.  This structure also puts so many points of contact on the solar cell that if it cracks there is minimal power loss.    

Benefits of Flexible Panels

Selecting RV solar panels can be tricky depending on your needs, but we found that these panels checked a lot of boxes for our RV solar system. 

First, these are very lightweight RV solar panels.  This is huge because weight is such a limiting factor in many RV solar builds.

Second, the ease of installation and there are no holes to be drilled in the RV’s roof, eliminating leak points.

Third, durability. These panels are also military grade and should take the beating that many RV solar panels. This may come from branches, UV degradation, and vibrations from just going down the road.

Disadvantages of Flexible Panels

Now, these panels do have their drawbacks as well, the biggest of which is heat dissipation. Hot solar panels perform worse, and being stuck to the roof with no airflow, these can get very hot. They can also dissipate that heat into the RV, making your living space hotter. 

The second biggest drawback is the cost. These panels are much more expensive than a similar glass solar panel alternative or other flexible competitors. As with any system, the drawbacks must be weighed against the positives of your situation.

We elaborate on the pros and cons of these flexible panels in another article. Overall, we love their look and their performance!

While these panels have worked extremely well for this installation and are still going strong four years later, we don’t necessarily recommend them. If you have the space and weight capacity, traditional residential panels are always the most cost-effective and efficient. There is no reason they cannot be used on RVs except for their weight and size limitations.

We split our combiner box into 3 busbars to handle the 3 solar circuits.
With 2 panels in series and the rest in parallel, our open circuit voltage of the roof was a bit over 50 volts.

We wired all the panels in a series-parallel configuration. We also utilized a special combiner box on the roof that allowed us to wire them in three separate circuits. From here the wires ran down to the electronics.

Inverter, Charge Controllers, and the Brains

Solar panels cannot be connected to the batteries directly. Therefore, they need a special charge controller between them and the batteries.

Charge Controllers

You need charge controllers because the panels’ power output will differ from what the RV batteries require for charging. This device converts it to the appropriate level and optimizes solar panel efficiency. 

With our Ultimate RV Solar install having so much solar power, we needed three separate charge controllers to handle the load and make the system more efficient.

We installed 3 Victron Smart Solar MPPT 100|50 charge controllers.

3 Victron 100 Volt | 50AMP charge controllers for the solar. Disconnects on the left and fuses on the right side.

Partial shading and different lighting conditions on some panels and not others – as we have on the front cap panel set – can negatively impact the performance of other panels on the same charge controller. But keeping them on their own controller prevents this, making the system more efficient.

Inverter

Connected to the battery are the RV loads and typically an inverter to convert the DC battery power to typical residential AC power.

Our past install utilized a Victron 3000VA inverter and for this build, we upsized it to a 5000Va Unit. (VA stands for Volt Amps and is a unit of power used for alternating current, similar to watts.)

This larger inverter can provide a lot of power to be able to run multiple large appliances at once. This includes the air conditioner! It really helps to make it feel like we are hooked up to the grid all the time.  We can run the microwave and Instant Pot at the same time, no problem! ​

The new 5K VA inverter installed underneath the batteries.

Converter

After installing the inverter there were only a handful of components left to install. First, the DC-DC converter changes the 24 volts of this battery bank to 12 volts that the RV’s DC appliances and lights use. 

Our first install was a 24-volt system, so this was not a change for us, and we could re-use the same Victron Orion 40 Amp converter we had used before.

victron orion

Battery Monitor

Lastly, we installed components that would monitor the system and allow us to make changes to its performance remotely. A battery monitor is essential in an ultimate off-grid system as it gives an accurate reading of the state of charge of the batteries

We used the Victron BMV712 battery monitor. ​The BMV712 is a 2-part meter that includes a shunt installed on the negative lead of the power system and this internal display unit installed in the RV.

Brains – Octo GX Computer

For our Ultimate System, we also installed a computer called the Octo GX. It is designed to communicate with the inverter, charge controllers, and battery monitor to wirelessly communicate the system’s data with an online portal.

This allows us to see how the system is functioning on a phone or computer. It shows solar energy, battery state of charge, AC and DC power, and how it is all flowing.

It also sends this data to the Victron VRM Portal. This allows us to log into the system remotely and see its performance in real-time. Here we are able to easily make programming changes to the system.

The Octo GX unit we are using as the brains of the system, it has no display but connects wirelessly to a phone or computer Below you will find a summary of the changes we made. 

Note the weights of the system components as this was a huge factor for us. We only had about 150lbs of additional weight that we would allow for this system. When all was said and done we came out only around 110 lbs heavier overall. We are thrilled since we increased capacity 3X on both RV solar panels and batteries!  

  Click here to see the list of system components:


Performance

We have been operating this system since June 2020, and things have been working great. 

We have traveled with this system over 10,000 miles, and all the connections to the batteries and electronics are still tight. All the panels stayed well-adhered to the roof, so were very happy about that!  

We have, however, switched to a different RV. But this power system is so good that we kept this RV primarily to use it for power generation at our off-grid camp. Yes, when we go to camp, we plug into this power system!

ultimate off grid RV solar power system

Large Loads

With the larger inverter, we have run multiple large loads. For instance, we use cooking appliances, hair dryers, and even the air conditioner a bit on sunny days. All of this we do without worrying about overloading it.

It really feels like we are living with the RV hooked up to shore power all the time.  We also love having the system connected online so we can monitor its performance.  ​

solar power production data graph

Solar Production Peaks

This is the dashboard for the Victron VRM portal that the Octo GX sends data to and can be accessed online. Overall, we see daily power output in full sun between 1600 and 1800 Watts. But we have seen peaks upwards of 2300 Watts.

vrm portal data

A lot of that power loss we believe is due to heat on the panels and will elaborate of this in a future post.

Front Panel Performance in Summer & Winter

What about those front solar panels?

While at first glance they may seem impractical, there is a method to our madness. You see, as full-time RVers, we chase 70 degrees and stay in our RV year-round. In the wintertime, the sun’s angle is much lower in the sky. The steep angle of the front camp, while a disadvantage in the summertime, is an advantage in the winter.

Let’s look at some numbers:

Panel
Section
Summer Peak
Performance*
Winter Peak
Performance**
Difference
Front Panels200W/460W = 43.5%340W/460W = 73.9%+30.4%
Roof Panels1500W/2300W = 65.2%1020W/2300W = 44.3%-20.9%
Total System1700W/2760W = 61.6%1360W/2760W = 49.3%-12.6%
*Sunny July Day in Michigan data; **Sunny December Day in Arizona data

In both instances, the nose of the RV was pointed directly south. One was in Michigan (summer) and one was in Arizona (winter).

Based on the data above, we see a few interesting things happening.

First, the winter peak performance of the front panels increased 30%!

rv solar panels performance in winter

Second, the roof panel performance decreases by 20%.

Third, the performance percentage of the front panels in winter exceeds the peak performance of the roof panels in summer. This is because while we have more direct and powerful sunlight in summer, the temperatures are higher – the panels can get upwards of 160 degrees F! This decreases the overall performance of the panels in summer.

Overall Takeaway

The best thing about the panels, however, is the weight and how that enabled us to put so much power on this RV’s roof.  Before finding these panels, we didn’t want to use flexible lightweight RV solar panels but now we are confident they will last. We have been able to max out the generation capacity off this 32 foot RV’s roof, hence why this is our Ultimate RV Off-Grid Solar install.            

Cost of Our Ultimate RV Solar System?

So a huge question we get asked is: what did it cost?  Considering we did all the work ourselves the components for this system would come in at around $17,000 retail. 

This may seem like a lot to spend on a power system in an RV, but there are a lot of factors to consider in the investment. So why might you do this?

For us, this is our home and we have no plans to leave the RV. So to have the amazing benefits that come along with not having to worry about power anywhere we go is huge for us. Solar power has changed our mobile lifestyle for the better and we couldn’t imagine not having it now.  

We also have a property that does not have power pulled to it. To get the utility to pull power from the road would cost more than $20,000 – so that right there makes it worth it!  We can have power on our off-grid spot and take it with us, too!

Why Do We Need Such a Large RV Solar System? ​

Well, we hate running our generator. We love the silence and ease of this system, and we love not worrying about having enough power or battery capacity.

That said, this system is oversized for our average daily power need, but this really helps with multiple cloudy days in a row or the shoulder and winter seasons when we don’t get as much sun.

The system is also large enough that on very hot summer days we can run the air conditioner on solar power to break the heat – a huge plus!

Tom scrubbing bugs off the front cap solar panels while traveling. We fill fuel at truck stops frequently and the semi window washer wands work well!

The trick is that when we don’t have a big electrical load and the batteries get fully charged that the power goes unused…unless we find something else to store it in.

Charging an Electric Car with Solar Power

We decided to dump the excess solar energy into a plug-in hybrid/electric car. Read all about how we did it here.


Need Batteries? Get $50 Off Per Battle Born Battery with discount code MORTONS at checkout!

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About Tom Morton

Tom, a Pacific Northwest native, is our technical genius. Born in Washington and raised in Alaska before settling in Michigan. He's the man who keeps our operation running, both figuratively and literally.

With a background in Electrical Engineering, Tom specializes in RV solar systems and lithium batteries. He made history as the first documented individual to use a Tesla battery module as an RV battery. Tom has personally assisted countless RVers with system installations and has educated thousands more through his videos and articles.

Cinematography is another of Tom's passions, showcased in his work on the Go North series. You can see his camera skills on display in The RVers TV show on Discovery Channel and PBS where he also stars as a co-host.

Tom's mechanical expertise extends beyond RVs to boats, planes, and all things mechanical. He's renowned for taking on maintenance and repair projects single-handedly and is often spotted underneath RVs, making him the technical backbone of our endeavors.

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Keith Doubleday

Thursday 8th of December 2022

Hello and thank you for the article about the flexible solar panel install. I am at a point of beginning my solar journey. Now that it has been a few years since you did your installation, can you share how the panels are performing? As you probably know, thee are a lot of opinions about the durability of flexible panels. I like to live in the fact world and hoping that you can share your results over a longer period of time.

Thanks in advance for any information you can share.

Mortons on the Move

Saturday 17th of December 2022

We share our experience with flexible solar panels in this article: https://www.mortonsonthemove.com/flexible-solar-panel-performance/

Ted

Sunday 20th of November 2022

I have a Battleborn system in my North Trail Travel Trailer and love it. We have 4 - 100amp-hr batteries, a Victron 3,000 Multiplus Hybrid Inverter along with the Victron color monitor. I'm now ready for solar panels but am worried about weight. I'm looking at the flexible merlin panels but have one last question before pulling the trigger. I know these panels glue on the roof, but how are they if you need to remove them at a later date due to warrantee issues or damage. Can they be removed without destroying the roof material? Also, thank you for all the solid information you provide over the internet. I know I can count on the information accuracy when I see your name attached!

Mortons on the Move

Wednesday 7th of December 2022

Glad you're enjoying our content. I have not tried to remove a merlin panel yet, but my guess would be that it would destroy the roofing. Im not even sure if you could get the panel off without damaging it. So many pros and cons to the different types of panels for sure. Weight was our biggest concern as well with that build.

Mike

Saturday 6th of August 2022

Where in Central Florida do I find someone who is an expert on the solar and can price it out to install on my 5th wheel?

David

Thursday 16th of December 2021

Tom, Thanks for all the great content. I learned a ton from you preparing for my solar install. I went with Rich Solar CIGS flexible panels on my travel trailer. The wind is starting to lift them a bit at the front of the trialer. I noticed you taped yours down around the edges. What did you use for holding the edges down? Thanks ahead, David

Mortons on the Move

Monday 7th of March 2022

So I got a few rolls of 3M Extreme seal but it's not readily available. Eternabond or the flexseal or gorilla tape equivalents are excellent options too!

Allan Lesniak

Friday 5th of November 2021

Love your videos, especially Go North... On our third time watching it! Hoping to go in 2022 (or 2023).

We recently bought 3 BB batteries and the Victron 12/3000 Charger. I have mounted everything under one of table benches and an open hole behind it (under a small counter space) - so its inside the travel trailer. I was trying to decide if I wanted to vent it to the side or roof. If I vented to the roof I would use a refrigerator vent on the roof (my leaning is to do it this way) or if I vented to the side I would use something similar to a stove top vent. I was planning to use 3" ducting to the exterior vents. I plan on using a fan or 2 to push air out of the space and have 2 vent openings feed the area where the inv/charger is located.

So, I have a question about the Victron Inverter/Charger 12/3000. How did you vent it? And how noisy is it? Thank You!!

Mortons on the Move

Monday 7th of March 2022

Hope you got it figured out, no need to vent the batteries and inverter to the outside, they generate a little heat but not much. The inverter is very quiet unless running a heave load or charging. If it gets too hot it will back down its charge automatically.