Advancements in solar and lithium-battery systems spearhead off-the-grid living

Renewable energy technology remains a moving target, and as this highly competitive industry continues to innovate, component prices are dropping as demand among the RV community continues to grow. Tariffs notwithstanding, the flood of less expensive products from China has also driven the market. That said, there are a few companies with a long-standing presence in the RV industry that focus on quality products, and Xantrex is arguably at or near the top of the list.

Xantrex solar kit
The Xantrex system comes with most of the needed items for the installation, but a roof clamshell, fuses, disconnects and wiring, including custom battery cables, will be required.

This year, Xantrex, a company long known for supplying inverter systems to the RV and marine industries, made the jump to mobile solar and lithium-battery systems, which made the company’s power-system offerings complete. Depending on the Xantrex system, all the components can be — or eventually will be — integrated into an app-accessible communications and control system.

The Xantrex Freedom XC inverter- charger
The Xantrex Freedom XC is a compact yet full-featured inverter-charger with an integrated transfer switch.

A renewable energy system has many benefits for RV owners, and lifestyle is important when considering the cost of the investment. The obvious benefit is having access to pure-sine-wave alternating current without running a generator when there are no utility hookups. But what else?

Many RV trailers and truck campers can be outfitted with an LP-gas-powered 5- to 6-kilowatt genset, while some RV owners strap on a portable unit for providing auxiliary power. However, gensets that are quiet enough to use in national parks are quite expensive, and quiet hours will dictate run times. A renewable energy system can reduce or even eliminate the need for the generator in most situations, depending on size and design.

These systems allow a much greater level of freedom and flexibility than relying on full-hookup campsites. The result is a net reduction in campsite expenses, as well as
the need to constantly refuel a genset.

Renewable energy systems are modular, which means you can start slowly with a foundation and build up componentry as needs and budget change. Then, perhaps most
significantly, these systems create zero emissions. They are truly clean sources of energy that emit no noise and no exhaust, and rely only on the sun’s rays for fuel.

Xantrex lithium battery packs wired in parallel
For the battery side of the project, two 125-amp-hour Xantrex lithium battery packs were installed in the Torklift PowerArmor Lithium security box. The two lithium packs were wired in parallel and secured in the box. A new master battery disconnect was installed on the bulkhead wall, and bulkhead wire connectors through the box were added for neatness. The system fuse was installed in the box as well.


Installing a mid-level system, like the Xantrex system presented in this project, is expensive, especially when component costs and labor are considered. In comparison, a portable inverter-generator runs about $1,200 to $3,000, though a built-in generator, like a Cummins Onan LP 5500 or 6500, will cost from $5,000 to $8,000 with installation. These options add up to hundreds of pounds in weight, consume fuel and have elevated noise levels, but they can run higher loads like air conditioners, if sized properly. Conversely, some renewable energy systems can run an air conditioner, but the cost of those systems is pretty high, and they take up a lot of space.

The solar landscape on the roof of any RV is an important factor, as the required energy determines the number of panels. The larger the RV, the more roof space can be dedicated to solar panels. The same goes for batteries, which take up storage space and add weight. Calculating the size of any system is an important first step. Sizing information for Xantrex systems is available in the Solar Selector Guide.


Like any system or building, a renewable power system starts with a good foundation. The foundation of the system consists of the wiring and batteries. Most importantly, the wiring has to be of sufficient size to handle the projected load and any future system expansion. Not only is cable expensive, it’s difficult to route, so if you think you’ll expand the system in the future, use a heavier gauge cable right from the get-go.

Batteries are the other foundational piece, and it’s essential to have enough capacity to handle the maximum amp loads, as well as enough reserve to get through a 24-hour charge/discharge cycle. Typical flooded lead acid (FLA) and absorbed glass mat (AGM) batteries will work, but lithium batteries offer a better option.

Lithium Batteries

Torklift International PowerArmor battery box Lithium-Battery Lockup

Security is a concern for RV owners who fork out thousands for a lithium-battery system, making a locking storage box worth considering. For example, Torklift International has developed a version of its PowerArmor battery box that is dedicated to lithium packs. The new PowerArmor Lithium (MSRP: $339.99) is an aluminum-diamond-plate box with partitions and lock-down bars inside that hold the packs in place, and the lid is secured with an integral key lock. Although the box is designed for outside use on a travel trailer, we opted to use it in place of a standard battery box inside the test fifth-wheel.

The current gold standard for RV battery technology is lithium-ion. Lithium battery packs are ideal for RV use. They’re light (less than half the weight of FLA counterparts), they accept a charge more quickly, and they provide steadier voltage. Where an FLA battery provides a usable capacity of 50 percent, lithium batteries provide up to 98 percent of the rated capacity, and the battery management system (BMS) will shut the pack down when it has reached maximum discharge. As an example, an FLA battery will provide 10.5 volts at a 50 percent state of charge, where a lithium pack will still be pushing 13.2 volts.

Lithium batteries have a much higher initial cost per pack than FLA or AGM configurations but offer a much better value over a long period of time. FLA and AGM batteries can handle from 300 to 500 charge/discharge cycles if optimally maintained, while lithium packs provide from 3,000 to 5,000 cycles over their lifetime and can be moved from rig to rig.

Xantrex’s new lithium packs offer 12 volts and a 125-amp-hour capacity, with a 10 percent reserve, according to the company. The packs feature an on/off button with LED status light and are accessible via a Bluetooth app on a smart device, which shows pack condition, load, charge rate, error codes and more. When using lithium batteries, it’s good to know the status of the system, and the app provides that valuable information.

Long-term storage isn’t an issue either. According to the Battery University website, FLA batteries self-discharge at 5 percent per month in storage with no loads. In general, lithium batteries will stabilize after charging and lose about 5 percent in the first 24 hours, but then only 1 to 2 percent on average per month, plus the BMS load. Xantrex’s lithium battery loses less than 3 percent of its residual capacity per month, or less than 15 percent per year of storage, according to the company.

Where this shines for RVers is in winter storage. Lithium batteries will not freeze, so as long as the temperature doesn’t dip below minus-40 degrees Fahrenheit for more than a month, the packs should be fine, although recommended storage is 59 to 95 degrees F. Alternatively, FLA batteries can freeze in storage if allowed to discharge, which results in cell destruction. Lithium batteries in use must be kept above freezing to accept a charge.
Lithium batteries can be installed in any position as long as the terminals are protected, including inside the RV, since they don’t off-gas, which is beneficial if using the RV in a cold environment.

Photo montage showing installation of inverter-charger

The fifth-wheel’s main distribution panel (top, left) was removed. Circuits were chosen to run through the inverter and removed from the panel to be relocated into a new subpanel. The subpanel and circuit breakers (top middle) were installed to provide a power feed from the main panel through the Freedom XC and back to the subpanel to feed the branch circuits. The bedroom, kitchen and microwave were run through the inverter. The living room TV will be added in the future but will require a cable run back to the panel. The three branch circuits (top, right) were removed from the main panel, and a new 30-amp feed to the subpanel was installed. The subpanel has a 30-amp main breaker (bottom, left), which is fed from the inverter and the three branch circuit feeds. The Freedom XC was installed in the front pass-through (bottom, middle) compartment on the ceiling between frame members. The back wall of the compartment was removed to access space for the routed cables (bottom, right) and provide a place to connect the chassis ground. Attachment of the wiring is made easier with quick-clips for the AC wiring and studs for the DC wiring. Make absolutely certain that polarity is correct, and check your work three times before applying power to any part of the system.


To realize all the benefits of lithium packs, you’ll need to have a programmable shorepower charger that can condition the pack as specified by the manufacturer. A combined pure-sine inverter and charger with an integrated transfer switch, like Xantrex’s Freedom XC, featured in this installation, will provide AC current simply by pushing a button and ensure that the expensive lithium packs are being charged optimally and safely.

Info Graphic on Xantrex solar installation projectThe Freedom XC is designed for a relatively easy retrofit installation and can be programmed for any battery technology using the preprogrammed algorithms for FLA, AGM, gel or lithium (LFE). For this project, the 2,000-watt Freedom XC with an 80-amp DC charger was installed.

The XC has an extended surge rating, which keeps it from shutting down too quickly when motors are started. It features a built-in 30-amp AC transfer switch and power-corrected DC charging to provide more AC shorepower for loads as needed. If the batteries are taken down to zero volts, which is what happens after a BMS shuts off a pack when the state of charge gets too low, the XC will still start a charge. Some units require that the batteries have at least a minimal state of charge, which would require owners to carry a separate battery charger.

Of note is the XC’s control interface on the housing, as well as the optional Freedom X remote panel. The display is identical on each, as are the controls, so operating and programming the myriad features on the XC can be done inside. While the XC didn’t offer smart-device apps at press time, that feature was not missed because of the convenience afforded by the remote panel. However, Xantrex is working on total connection and integration communication across all of its products, similar to that in the SW series, according to the company.

Photo montage showing setup of solar panels and wiring
When installing the peel-and-stick solar panels, (top, left) denatured alcohol must be used to ensure the surface is as clean and dry as possible. After the panels were positioned on the roof and the corners were marked, the backers were peeled off (Top, middle) , and the panels were stuck in place. Each panel was rubbed out (top, right) to ensure it adhered well to the surface. Xantrex kits come with ready-made cables and junction connectors (bottom, left). We opted to add a solar fuse to each panel (available on Amazon) to further protect the wiring. As an added bit of security, EternaBond tape was placed around the perimeter of the panels (bottom, middle), which is not technically necessary but helps ensure the edges are not caught or that water doesn’t find its way underneath. The cables were routed into the roof (bottom, right) and sealed. The panels remained disconnected until the installation was completed.

Solar Panels

Xantrex’s entry into solar was a long time coming, and the quality of the product was worth the wait. Again, Xantrex was focused on offering a complete off-grid RV power system, so building its own solar systems was the logical next step.

The Solar Max flexible panels have peel-and-stick mounting provisions that require no drilling for installation, although drilling will likely be required for routing the cable through the roof. Still, far fewer holes are required than with a frame-type panel. The panels are available in 80-, 165- and 220-watt sizes in basic kits that include most of the cabling and parts needed for a typical installation, including a 30-amp charge controller. Expansion kits don’t include the controller.

The monocrystalline panels, which carry a five-year warranty, are built to withstand the rigors of RV use, according to the company. The panels are claimed to have up to 180 degrees of flexibility, are 20 percent more efficient in shade and are significantly more durable than other flexible panels because of their mesh-grid technology.

Photo montage of solar controls and wiring
The system includes a programmable 30-amp solar controller (top, left) with USB charging ports, but a 55-amp controller is available through Xantrex if required for a larger array. Littelfuse’s LPSC/M Powr-Safe fuse holders with Class CC
30-amp fuses were mounted to a DIN rail. They act as a disconnect and provide circuit protection. An indicator on the front shows when the fuse is blown. While replacing the stock converter in the test fifth-wheel with the Freedom XC, it was determined that the converter’s power tap could be used as an input for the solar system (top, right). This may not be possible in every installation, making it necessary to have a dedicated wire run all the way to the battery bank. The Freedom X remote was neatly installed in the control cabinet inside the fifth-wheel (bottom, left), which affords the owner a readout of system status (bottom, right), as well as full control of the Freedom XC from the living space.


Photos showing screens of the smartphone app
Status Check: The Xantrex battery app connects to a smartphone and shows the condition of the battery (above left), temperature, charge status and more. The code screen (above, right) provides diagnostic data, should the system shut down for technical reasons.

For the avid do-it-yourselfer who is comfortable with advanced electrical procedures, this project can be tackled easily at home with the understanding that there is quite a bit of modification and some fabrication needed to complete the installation. For safety, it’s essential that all applicable codes and standards are followed (NFPA 1192 and NEC-551 are available online). If you’re uncomfortable working on the roof, then it is best left to the pros.

Cables must be sized correctly, and you’ll need the equipment and parts to install and seal the cable ends. Be sure to protect all wiring with the appropriate overcurrent devices.

Spend time taking a close look at existing components and wiring, both DC and AC, predetermine where the components will go, and decide which circuits (up to 30 amps) will be fed by the inverter. In most situations, an AC subpanel will need to be installed and wired in, and an extensive wiring run from the subpanel to the inverter-charger will be required.

Post installation in the test fifth-wheel, the Xantrex system was put through its paces, and all has worked as designed and expected. The system now provides component and installation versatility to really enhance off-grid livability.

Chris DoughertyChris-Dougherty-headshot is technical editor of Trailer Life and MotorHome. Chris is an RVDA/RVIA certified technician and a lifelong RVer, including 10 years living full time in an RV. He and his wife make their home in Massachusetts and hit the road in their heavy-duty truck towing their travel trailer every chance they get.

See more Trailer Life articles about RV Solar power:

Unplugged: RV Solar Systems

Solar-Power Survival in Yosemite

How Much Solar Do I Need on My RV?



  1. As always with the solar power proponents, they fail to acknowledge the fact that all their hype ignores one reality: everything is based on continuous access to direct unfiltered sunlight. Amazingly, they never tell you what it would take to camp under a tree. They always go “off the grid” in the desert or other wide open locations, most of which don’t have a tree within a 100 miles. Never are they in the upper Midwest where we have forests (land covered with trees) and people desire to camp in them.

    Since your article pretty much was an advertisement for Xantrex, I’m sure they could have given figures for the cost of solar systems. The problem is that your reader could then easily compare solar cost to generator cost. You noted that a large genset was expensive but failed to acknowledge that a solar system would cost multiples of that. I’m sure Xantrex could have priced one for you.

    There are locations where solar is feasible due to an abundance of sun and lack of vegetation, as long as you can pay the price. However, these location are limited, and Trailer Life has spent way too much time and print pushing it.

    • Thanks for your comment, Michael. The costs for solar and inverter systems continue to drop, and if you look at the black text box in the article above, you’ll see the MSRPs of all the equipment used in this article. Also as stated, consumers should always research which equipment works best for their needs.

      With respect to shade use, most panels sold for the RV space have polycrystalline cells. While slightly less efficient in super hot conditions, these panels will continue to provide various levels of charge depending on the amount of sunlight the cells are exposed to. Monocrystalline cells, on the other hand, can shut down completely if not exposed to 100 percent sunlight. That said, yes, charge rate will be reduced in your environment, possibly requiring another charging medium.

      Lastly, this is not an “advertisement” for Xantrex. However, when we have an opportunity to work with a vendor to complete a project to bring edit like this to our readers, we will try to take advantage of it. We are, of course, grateful to Xantrex for working with us on this, as they and other vendors have done for years for our magazines and other automotive and RV publications.

  2. How much of a solar system would you need to just keep charged the standard 12-volt battery required to run LP-gas appliances: refrigerator, stovetop and plugging into the Furrion plug that comes with the Coleman campers that are advertised in your magazine?


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