rv solar battery charger

The Best Solar Chargers For RV Battery to Buy in 2022

If you like to boondock in far-off destinations, or you simply don’t want to be dependent on the power outlets at crowded RV campgrounds, having a solid RV solar battery charger installed on the roof of your motorhome is the ideal solution. That way, you can charge your batteries and power electronics inside your rig. Plus, these systems will keep your precious batteries healthy. 

While shopping for the best RV solar battery charger might be intimidating due to the technicalities, we will make your buying experience as painless as possible. Dive right into our handpicked list of the best solar panel for camper battery for extended off-grid stays; there’s something for everyone, regardless of your power demand or budget. 

If you’re not familiar with this new technology, worry not, we also cover everything a beginner needs to know about RV solar battery charger to make an informed decision. Learn how an RV solar battery charger, the different types, the criteria to go over, a list of prestigious suppliers and answers to frequently asked questions.

Best RV Solar Battery Chargers: Quick Recommendations

NoBest RV Solar Battery ChargersPricesOur Ratings
1SUNER POWER Solar Battery Charger$$*****
2Sunway SWS-C2W001$****
3Eco-Worthy AM-P20X-CB-1$$$*****
4Topsolar 30W Monocrystalline$$$*****
5SOLPERK 20W 12V Waterproof$$*****
6POWOXI Solar Battery Charger$$****

The Basics About RV Solar Battery Chargers

What is it?

There are three ways to charge your RV battery: plug your rig into shore power at your home or at the campground, use an RV generator to top it off, and install solar panels on the roof of your motorhome to create electricity from sunlight. This third method means you can still satisfy your power demand during extended off-grid stays with no power outlet or generator, as long as you get some sun.

Just like with residential applications, using solar powered battery charger for RV has become increasingly popular, especially for the full-time travelers. In addition to its environmental friendliness, using an RV solar battery charger allows you to charge your rig’s battery as well as powering everything electrical inside your RV when you don’t have access to shore power, including the lights, A/C, water heater and appliances.

How it works 

Solar Panels: The solar panels are the flat sheets made from silicone crystals encased in glass. When sunlight hits the surface of the panels, the energy from the sun gets absorbed by the cells in the panels. The photons from the sunlight knock the electrons in the panels free from atoms, creating an electric field that causes an electrical current to flow. 

Charger Controller: Now electricity is generated, but it cannot be readily accepted by the battery. This is because for proper charging, the battery in your rig requires a specific ideal voltage and current. This is where the solar charge controller comes into play: it converts the generated electricity into something usable for the battery. Small RV solar battery charger models on the market often include built-in charge controllers, while larger setups often use independent or standalone-unit charger controllers.

Your RV battery will store the converted sunlight energy for use at night, so you can still power your motorhome when there’s no sunlight. When the stored energy is used, the charge controller will know that it needs to create more energy from the sun to recharge the battery.

A major role of the charge controller is, as its name suggests, is to control or moderate the energy input from the sun. When there is too much sunlight, the battery can be overcharged and suffer damages, so to prevent this, the charge controller detects the voltage in the battery and adjusts the output from the solar panels down to a safe level. The charge controller also shortens charging time, or increases charging efficiency, by maximizing the current that the panels produce.

Inverter: An RV solar battery charger converts sunlight from the sun to power usable for the battery with the help of the charge controller, but this usable power is not directly usable for the appliances in your RV. What is stored in your RV battery is 12 volt DC (direct current) electricity, while RV appliances, including TVs, computers, microwaves, and fans, use 120 volt AC (alternating current) electricity. This is where the inverter comes into play, that is converting the DC electricity for AC applications. When you purchase a standalone inverter for use in your RV solar battery charger, just make sure it is rated to handle your typical electrical loads.

Benefits of RV solar battery chargers

Opens up travel opportunities: A solar powered battery charger for RV makes you less dependent on the availability of power outlets at traditional campgrounds. You also won’t need to haul around that big and heavy generator. 

This means you can travel to far off places off the beaten path but can still enjoy all the electrical creatures of comfort inside your motorhome while keeping your battery charged. This also means that for the travelers who prioritize privacy, you can stay away from the busy and noisy campground packed with other motorhomes and enjoy nature to the fullest. 

A long-term investment: If you’re still on the fence regarding the initial investment, remember that RV solar battery chargers will be of good service to you for decades down the road. Solar panels have no mechanical moving parts that would wear out and need to be replaced. When you’re no longer traveling and wish to sell your motorhome, the solar panels you have on the roof will undoubtedly increase the resale value of your RV.

Extends battery life: Continuous deep discharges would shorten the lifespan of the lead-acid batteries in your RV. Having a solid RV solar battery charger properly installed would ensure that your battery gets topped off in a slow and steady manner at all times, which is ideal for lead acid batteries’ lifespan. We all know that RV batteries are not cheap, not to mention that having a dead battery can leave you stranded in the middle of nowhere.

Furthermore, the best RV solar battery charger products on the market would have a charge controller in place, so you never have to worry about overcharging your precious battery. Overcharging is undesirable, as it results in overheating, decreased charging efficiency and shortened battery life. 

The charge controller makes sure that once the battery has reached a sufficient level of charge, the system would just supply the battery with the right amount of current to keep it at full charge, i.e. trickle charging. This is why these systems are also called solar trickle charger for RV battery.

solar powered battery charger for RV
Photo: Anetlanda / ShutterStock

Quiet: While a generator is very noisy, these systems are perfectly quiet, so you can enjoy nature in peace and avoid disturbing wildlife.

Travel green: And of course, an apparent benefit of using RV solar battery chargers is that you’re doing our planet earth a favor. Solar panels consume no fossil fuels and do not produce any harmful emissions. It is 100% clean and sustainable.

Safe: An RV solar battery charger system typically operates at less than 30 amps and at 12 volts, which means it’s inherently safe. The chance of electrical complications that can cause fire hazards or electrocution is negligible. 

Cost

Solar panels are now used for many applications, so you can easily find them from many sources, both online and offline. You have many choices to create a customized solution for your camping needs. Plus, there are ample reviews and installation tutorial videos that you can rely on. 

One solar panel typically costs you between $50 and $300, depending on the size, efficiency and durability of the panel. In general, the bigger the panel, the more energy it can produce at any given time to charge your RV’s battery and power it.

Types of RV Solar Battery Chargers

Depending on your power demand, you can choose among three types of RV solar battery charger systems:

RV Solar Battery Tenders

A solar battery tender “tends” to the battery in your RV. That is it delivers minimal current to maintain the charge in the battery i.e. avoiding too deep discharges, which is not ideal for the battery’s health. 

These battery tenders are smaller in size and their main purpose is to avoid the situation where you are away from your RV for a while and come back to find the battery completely dead. Unlike larger RV solar battery charger systems that can serve as a primary power source to power up your entire rig, these tenders are used to keep the battery topped off when you’re not looking.

Portable Solar Panels

These all-in-one kits usually include everything you need for installation. They are larger in size than the tenders and can meet basic electrical needs like powering the lights and electrical appliances in a motorhome. Depending on their watt range, a kit like this might or might not be powerful enough to operate power-hungry air conditioners or heaters. 

These portable systems can easily be uninstalled, unlike the built-in systems below. There are even kits that are so lightweight you can carry around anywhere for use away from your RV. Some are even designed to be strapped to a backpack for flexible camping applications.

Thanks to their adaptability, portable RV solar battery chargers have seen rising popularity and currently offer three types:

  • Monocrystalline panels: This class is the most expensive but also the most effective in terms of power output. Each panel is made from one large single silicon crystal, which is part of the reason why they can produce energy for your RV even in weak sunlight, while solar systems of other types typically only produce power during about 5 to 6 hours of peak sun each day.
  • Polycrystalline panels: These panels are made from multiple silicon blocks instead of a single silicon crystal like their monocrystalline counterparts. This construction means they produce less power than monocrystalline solar panels, but they are widely used since they are more affordable and also take up less space on the roof, which allows for more flexible setups. 
  • Amorphous panels: This type of thin-film panels are made from silicon spread on a large bed. This construction makes them flexible, enabling more options in terms of installation. Although amorphous solar panels take up as much as three times the space compared to the other two types, they are still widely used thanks to their affordability.

Large Built-in Solar Systems

Unlike the tenders and portable kits, larger systems are built into an RV and come complete with solar panels, charge controllers and complicated wirings. They are not for the novice. In addition to charging your RV battery, these systems can generate more power to serve as a primary power source and power up your rig, including running the appliances that consume a lot of electricity like A/C, heater, oven and vacuum cleaner.

Best RV Solar Battery Chargers For The Money

Without further ado, below are the best RV solar battery charger kits on the market in terms of efficiency, power output, durability and value for money.

There is something for everyone, whether you just need an entry-level kit for minimal power consumption or a larger system to power up an oversized motorhome.


1. Best Overall: SUNER POWER 12V 6W Solar Battery Charger & Maintainer

SUNER POWER 12V Solar RV Battery Charger
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Wattage: 2.4W at $29.95, 6W at $39.95, 8W at $45.95, 12W at $55.95 and 14W at $59.95

Size: 6W – 16.73 x 10.43 x 2.51 inches

Applications: Wet, Gel, SLA, AGM, deep cycle batteries in RVs, trucks, cars, motorcycle, boat, marine, tractor, Powersports, snowmobile.

Why we love it:

The Suner Power BC-6W 12V is one of the best RV solar battery charger and maintainers out there in all aspects. It is made to top off flooded, gel, SLA and AGM deep cycle batteries in an array of different applications, including RVs, trucks, tractors and boats. The 12 volt 6 wattage model has our pick, since it should accommodate most average camping situations with the most bang for your buck, but there are other sizes to cater for different power demands: 2.4W, 8W, 12W and 14W.

The manufacturer claims that this highly efficient RV solar battery charger can deliver a 20% higher conversion rate than their competitors, so it can produce more power even in weaker lights. The Suner Power BC-6W also boasts built-in blocking diodes to prevent reverse discharge, so that it will not drain your RV battery. 

Its rugged construction is made to last, with an upgraded extra durable ABS plastic frame covered with premium strong solar glass. It has received showers of praise from full-time RVers on how well it can withstand beatings on the open road. The manufacturer’s extended 12 months warranty plus lifetime technical support also speaks volumes about the reliability of this stellar RV solar battery charger. 

Last but not least is easy installation and flexible options for setups, as the kit includes 4 suction cups for easy mounting, plus 2 interchangeable clamps and cigarette cables, so even first-time users can easily mount whichever way works best for their rig.

Great little product

Got this for our travel trailer that we keep at a storage facility without electricity available. I keep this on my already fully charged battery and it keeps it topped off and in good condition. Remember this is just a trickle charger to keep an already charged battery good to go. Have only been using it for about a month and it seems to be working great; I check the battery with a multimeter and the battery is always fully charged after a week or two.

Shared by Deb Flickinger

Kept our RV batteries charged!

We were having problems keeping our rv batteries charged while in storage until we used the Suner Power Charger. Hooked it up and it worked great. Perfect solution at a reasonable price. Super easy to install. Couldn’t be happier!

Shared by Marta Beman

Pros:

  • High-wattage options available
  • Easy to install
  • Rugged construction
  • Reverse discharge protection

Cons:

  • Some buyers noticed deviations in power output

2. Best Value: Sunway SWS-C2W001 12V Solar Battery Trickle Charger

Sunway Solar Battery Trickle Charger & Maintainer 12V
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Type: Amorphous solar panels

Wattage: 1.5W at $23.39, 4W at $32.39, 5W at $35.99 and 8W at $44.99

Size: 13.9 x 5 x 0.5 inches

Applications: any 12 volt battery in RVs, trucks, cars, marine , motorcycles , tractors, ATVs, snowmobiles, boats and personal water crafts

Why we love it:

The Sunway SWS-C2W001 is no doubt one of the best selling RV solar battery chargers out there, amassing a 4.3 star overall ratings from almost 4,000 buyers on Amazon alone. This is a tried and true 12 volt battery maintainer for a variety of applications, offering four models with capacity ranging from 1.5W for small sized vehicles and RVs up to 8W.

Based on thousands of customer reviews, this amorphous solar system is covered with ultra clear PV glass, enabling it to be more efficient and works well even on cloudy days. It steadily charges deep cycle batteries with no risk of overcharging. It also boasts a built-in blocking diode to prevent reverse charging and blue flashing LED charge indicator for easy monitoring. 

This solar powered battery charger is affordable, and even more so when it’s proven to last many years down the road. Its durable ABS plastic housing allows it to withstand extended exposure to harsh outdoor elements and all the physical impacts on the open road. What’s impressive is this: the manufacturer notes that although this charger can withstand splashing, it is not fully waterproof and thus should not be left outside during rainfall. But in reality, countless buyers have used this charger on their RVs and boats and leave it outside 24/7 in all weather conditions, including heavy rains, all without a problem and with minimal maintenance.

Easy and flexible installation is also a huge perk.This RV solar battery charger can be mounted to the windshield or dash. It conveniently plugs into your RV’s 12 volt cigarette lighter with the 2.4-meters long cable or connects to the battery using the crocodile clips provided. Suction cups are also included in the kit for more setup options.

I bought this to maintain the charge on my RV batteries, which it does. Only very recently have I tried using it to charge my motorcycle battery. For that, it works REALLY well! At first, I was a confused about what seemed like a miswired connection, but after a quick exchange of emails with Sunway Customer Service, I am no longer confused. The Sunway Solar Car Battery Charger is a high-quality piece. It comes with multiple connections, a long cord and and two methods to mount it to a surface, making it totally portable. It has become the only battery charger I use! I recommend this product.

Shared by Bill B.-Texas

A must for any RV motorhome owner!

This trickle charger is so easy to use… just plug into your cigarette lighter (one that stays “hot” w/ no ignition key”, make sure it gets some sunlight, and no more dead engine batteries after a couple weeks of your RV sitting in storage. It is solid and well built. I highly recommend.

Shared by Bearcat Chris

Pros:

  • Affordable
  • Flexible setups
  • Durable construction
  • Reverse discharge protection

Cons:

  • Some complaints about missing accessories
  • Some complaints on deformation after extensive outdoor exposure

3. Editor’s Choice: Eco-Worthy AM-P20X-CB-1 Waterproof 25W Solar Panel

ECO-WORTHY 25 Watts 12V Off Grid Solar Panel SAE Connector Kit
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Type: Polycrystalline solar panels

Wattage: 10W at $32.99, 25W SAE kit at $52.19

Size: 16.97 x 13.23 x 1.42 inches

Applications: maintainer for 12 volt battery in RVs, trucks, cars, boats and any off grid applications using 12 volt deep cycle battery including chicken coop, gate opener, water pump, shed, cabin 

Why we love it:

This Eco-Worthy RV solar battery charger is true to its name: an environmentally friendly solution for extended off-grid camping and a wide range of other applications. The AM-P20X-CB-1 solar kit is also one of the best out there among models that offer high wattage output for such a reasonable price range. 

While the 10W kit at just over $30 is excellent value for money, the fully waterproof 25W kit that comes with SAE connectors cable at $52.19 is such a steal, it’s our Editor’s Choice. With a capacity of 25W, this RV solar battery charger can easily top off your battery while powering other electronics in your motorhome, so you won’t have to worry about overloading your system.

At that price and power output, this polycrystalline Eco-Worthy AM-P20X-CB-1 panel is very extra competitive when compared with other polycrystalline and amorphous models on the market. The kit even includes a USB charge controller to prevent overcharging, reverse discharge, short circuit and reversed polarity. 

Even the novice can get away with the forgiving plug and play installation. The kit includes a 25 watt monocrystalline solar panel, a 9.8-feet SAE connectors cable, a 10A USB port charge controller with SAE connector, plus battery alligator clips with 18.5 inches SAE connector cable and one O-Ring Terminal with 16.9 inches SAE connector cable for direct battery connection. The two indicators allow you to easily check the status of charging and discharging. And should you encounter any problem during installation or thereafter, take advantage of the 24/7 technical support team and the 1 year warranty.

Cool little package. Would be great if they included an in line fuse instead of suggesting you add one. Having soldering iron, heat shrink and a little experience wasn’t a big deal. Was easy install on my RV to keep the two marine batteries charged while stored. Working great a month later.

Shared by Walter C.

Pros:

  • High wattage output at reasonable prices
  • Totally waterproof
  • Comes with USB charge controller
  • Easy plug and play installation

Cons:

  • Some complaints about the cables not being fully waterproof
  • Some complaints about dysfunctional charge controller that might need several tweaks
  • Some complaints about missing mounting hardware

4. Topsolar 30W 12V Monocrystalline Solar Battery Charger 

Topsolar Solar Panel Kit 30W 12V Monocrystalline RV Battery Charger Maintainer
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Type: Monocrystalline solar panels

Cell efficiency: 19.5%

Wattage: 30W at $64.99

Size: 24.8 x 13.9 x 2.3 inches

Applications: maintainer for 12 volt batteries in RVs, car, cabins, boats, marines, shed, cabin, gate opener, battery operated gates, dry camping, garden watering.

Why we love it:

This kit is more expensive than the previous models, but it is a highly efficient monocrystalline solar panel with superior power conversion that works well even on cloudy days. While most RV solar battery chargers on the market have a cell efficiency of 15% to 18%, this Topsolar kit boasts an impressive rate of 19.5%, which over the long term can make such a difference. With a hard-to-beat capacity of 30W, it can tend to your RV battery while powering up even the most power-hungry luxury motorhomes, as well as for use in other off-grid and backup power applications.

You’re also getting excellent value for money, since this is a tried and true RV solar battery charger in terms of durability. This weatherproof monocrystalline solar panel boasts a heavy duty construction with corrosion-proof anodized aluminum frame and tempered glass coating, allowing it to withstand a lot of beatings from mother nature.

As for installation, this is a true plug and play kit, which includes a 30 watt solar panel, a 10A 12V/24V charge controller and two 6.5ft cables with alligator clips and O-ring terminal for direct battery connection. The included charge controller prevents overcharging, discharging, overvoltage and short circuit.

Pros:

  • Unmatched cell efficiency
  • High power output
  • Extra heavy duty construction

Cons:

  • Some complaints about poorly written manual

5. SOLPERK 20W 12V Waterproof Solar Battery Trickle Charger 

SOLPERK Solar Panel Kit 20W 12V, Solar Battery Trickle Charger Maintainer
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Type: Monocrystalline solar panels

Wattage: 10W at $37.99, 20W at $49.99, 30W at $74.99, 50W at $89.99, 100W at $94.99

Size: 20W – 14.6 x 13.2 x 0.7 inches

Applications: maintainer for Wet, Gel, MF, EFB, and AGM 12 volt batteries for RV, car, boat, marine, camper, lawnmower, motorcycle, jet ski, water pump, shed, gate opener.

Why we love it:

This SOLPERK kit is another best seller in the monocrystalline category. It offers different versions, going from 10W all the way to 100W, so there is something for everyone, regardless of their demand for power. Our pick is the 20W kit available at $49.99, which is sufficient for most average camping applications. It was recently upgraded for optimal cell efficiency, reduced cell loss, and a longer panel life. 

As confirmed by countless full-time campers, this highly efficient monocrystalline solar charger delivers well even in low-light environments. The conveniently included charge controller will ensure that your battery is topped off at the right amount of current based on the battery’s voltage so as to avoid overcharging and extend battery lifespan. 

You are going to get a lot of use out of this RV solar battery charger down the road, thanks to its rugged construction that uses tempered glass, weatherproof film, and aluminum frame that can withstand extended exposure to brutal outdoor use for more than 10 years.

The kit includes, apart from the 20W fully waterproof solar panel, a solar charge controller, 2 alligator clips, a SAE extension cable and an adjustable mounting bracket, which can rotate 360 degrees so that it can receive the most direct sunlight. The mounting accessories also allow this solar panel to be mounted on the roof as well as on the ground or a wall. Should you encounter any issues during setup or afterwards, take advantage of the extended 12 months warranty and 24/7 technical support.

Pros:

  • Fully waterproof
  • High power output
  • High cell efficiency
  • Heavy duty construction

Cons:

  • Charge controller sometimes acts up

6. POWOXI Solar Battery Charger 12 Volt 10W Solar Panel Kit

POWOXI Solar Battery Charger 12 Volt 10W Solar Panel Kit for RV
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Type: Polycrystalline solar panels

Wattage: 10W at $41.99

Size: 14.84 x 8.86 x 2.09 inches

Applications: maintainer for 12 volt Wet, Gel, SLA, AGM batteries for RVs, trucks, cars, boat, motorcycle, marine, tractor, Powersports, snowmobile.

Why we love it:

If you don’t need a high-wattage solar kit, the POWOXI 10W RV solar battery charger is a solid choice. Although for about $40, you’re not getting a whole lot in terms of wattage, this highly efficient polycrystalline can convert more sunlight into usable electricity in low-light conditions.

This polycrystalline solar panel is weatherproof and made to withstand both extreme high and low temperatures, thanks to its industrial grade, impact-resistant ABS housing and low iron toughened glass. The manufacturer’s 12-month warranty and lifetime technical support should speak volume about this unit’s reliability and durability. 

The kit includes everything you need for easy and flexible plug and play mounting: a 10W solar panel with a 8.2ft cable, alligator clips with 1.6ft cable for direct battery terminal connection and a 1.6ft cable for charging the battery via the cigarette lighter socket, plus 4 powerful suction cups for more setup options. Other desirable features include built-in blocking diode to prevent reverse discharge and indicator light.

Pros:

  • High efficiency
  • Fuss-free and flexible installation

Cons:

  • Some complaints about cracks on plastic housing

Choosing The Best RV Solar Battery Charger: Buying Criteria

Choosing the right solar panel to charge RV battery all depends on your power needs, for instance, whether you just need an RV solar battery charger to top off the battery to keep it healthy, or something as a primary power source for your power-hungry motorhome.

rv solar battery charger
Photo: Adventurous Way

Solar Cell Efficiency

A crucial specification for an RV solar battery charger is the efficiency, expressed in percentage. It measures how much the energy in sunlight that an RV solar panel absorbs can be converted into usable electricity by the panel’s cells. 

The higher the efficiency rating of a solar panel, the better it will do its job, and thus the fewer number of panels you will need to meet your rig’s power demand. The majority of solar panels on the current market have an efficiency rating of between 15% and 18%, with a few boasting slightly higher numbers. This number is relatively low because, remember, the panels can only produce power from direct sunlight that hits its surface, not diffuse light or indirect sunlight that bounces off something.

Capacity/Wattage and Price

In terms of size, RV solar battery charger systems can be divided into the smallest battery trickle chargers, small-size systems, medium-size systems and large-size systems:

10-50 Watt Trickle Chargers: If you don’t boondock but just want a charger in place to maintain the charge in your battery, and one that charges it steadily at minimal current at that, you only need a 10 to 50 Watt RV solar battery charger. A 10 watt solar charger is sufficient to maintain the optimum level of charge in your RV’s 12 volt battery.

Although all three types of solar charging systems – tenders, portable kits and built-in systems – can trickle charge your RV battery, getting something larger than you really need means you’re getting little value for your investment, since the price of an RV solar battery charger increases with its power generating capacity.

50-100 Watt Chargers – Light Use: These small solar systems can charge the battery during the day and provide power during the night for light uses of small electronics, cellphones, and energy-efficient LED lights. These systems are not powerful enough to run fridges, computers, TVs and A/C or heaters. In short, they are most suitable for the small and minimal Class B minivans.

100-600 Watt Chargers – Medium Use: If you wish to power TVs, computers, fridges, ovens or cooling/heating systems, you will need at least a medium-size RV solar battery charger that is capable of at least 100 Watt. The general rule of thumb is that if you own anything other than a Class B minivan, you would need at least two 100-watt panels, or 200 watts in total. 100-watt panels are the most common or standard size for RV solar battery charger these days, that is why campers usually ask questions like “how many 100W panels do I need for my power demand?”

Note that for light AC applications like running the TVs or PCs, you will need an inverter. Depending on your power needs and whether you tend to run many appliances at one time, you might need to pair your solar charger with a generator as a backup, which is commonly done. The solar system will significantly lessen the load on the generator should you need it.

600-4000 Watt Chargers – Heavy Use: If you tend to power many appliances at the same time, or if you own a big Class A or Class C motorhome fully equipped with a lot of amenities, you will need a heavy duty RV solar battery charger that is capable of up to 4,000 Watt. A rule of thumb is for boondockers who tend to take long off-grid stays, you would need a system capable of 1,800 watts or more. 

Such a powerful system will allow you to operate everything you need, including the air conditioner, without the need for a generator. Unlike the smaller chargers, these heavy-use solar systems always include an inverter for AC applications. Accordingly, they are ideal for boondockers who like to stay in the wilderness for long periods at a time.

Related: Best RV Battery for Boondocking

The Capacity of Your RV Battery

While the above section provides you a rough guide, you can calculate the minimum wattage that your RV solar battery charger would need to charge your RV battery, based on the battery’s total capacity. The capacity of a 12 volt battery is measured by amp-hour rating, that is the number of amps of power the battery can deliver at usable current (defined as 10.5 volts or higher) for 20 hours of total available use. 

For instance, an RV battery is rated at 100AH or amp-hour. Divide this number by 20 (that is the standard 20 hours of total available use, or any other number specified by the manufacturer), you get a capacity of 5 amps per hour. Assuming we are charging this battery at 12 volts and 5 amps, your would need a solar charger capable of at least 12 volts * 5 amps = 60 watts. To be safe, you should get one 100 watt panel or above.

* More on choosing the right size of solar panels for your needs:

If you wish to be more exact, the surest way to choose the right size of RV solar battery charger is to add up the electrical loads of all the appliances that you would likely run at the same time, then get a system that can at least accommodate that power demand. 

A general guide is a 100 watt panel, which is the most common these days, can generate about 6 amps per hour of peak sun, which translates to around 30 ampere hours every day. Meanwhile, if you’re boondocking, you would need at least 80 ampere hours per day.

You can find the voltage and current demands of an appliance on its nameplate. For instance, most RV fridges on the market are rated for between 1 amp and 6 amps per hour. Multiply this number by 24 hours and the appliance’s operating cycle, expressed as a percentage, and you will get the ampere hours. For example, if a fridge pulls 6 amps per hour and has a 40-percent cycle, its daily power consumption will be 6 amps x 24 hours x 40% = 57.6 ampere hour per day.

The Type of Battery Your RV Has

Lead Acid Batteries: Lead acid batteries, including flooded, get and AGM batteries, should not be made to withstand deep discharges, or else their lifespan will be shortened. It is important to charge your lead acid batteries daily if you don’t want them to suffer a premature death. 

For this reason, if your RV comes with this type of battery, you will need a large size solar system, since a small size system would charge the batteries too slowly. In most cases, RVers who like to boondock from time to time would pair their RV solar battery charger with a generator to ensure sufficient charging capacity.

Lithium Batteries: Although lithium batteries cost much more than the lead acid type, they last longer, do not need to be recharged everyday and can withstand deeper discharges without sustaining damages. As such, you might not need a generator as a backup plan, and depending on your power need, you might be able to get a smaller size RV solar battery charger.

Weight and Size

Portability is also an important factor when you’re camping. The solar panels must not protrude from your RV rooftop, and make sure that your RV and your towing truck, if any, will be able to handle the extra weight of any RV solar battery charger kit you will be carrying around without any damage to your motorhome.

Best Seller List of RV Solar Battery Chargers

[amazon bestseller=”RV solar battery chargers” items=”3″]

RV Solar Battery Charger: FAQs

1. How long does it take for a 100W solar charger to fully charge a 12 volt battery?

The exact answer to this question depends on the type of battery, the ambient temperature, and panel and charger efficiency. A 100 watt RV solar battery charger can take anywhere between 5 hours and 17 hours to restore a 12 volt RV battery to a full charge. An example of the basic math is as follows:

Assume you have a 12-volt 100AH battery. You drain the battery down to 60%, which means you have consumed 40% of 100AH, or: 40% * 100AH = 40 amp-hour that particular day.

Assume you have one 100 watt panel. This panel produces about 6 amps per hour during peak sun. 6 amps of current from the solar charger delivers a charge of 6 amp-hour every hour, so to make up for the 40 amp-hour that you consumed that day, it would take the 100 watt solar panel: 40AH / 6A = 6.67 hours to charge the battery up to 100%.

2. How many 100W solar panels do I need to charge a 12 volt RV battery?

This depends on many factors, including the capacity of your RV battery and the efficiency of your RV solar battery charger. The capacity of your RV battery is measured by its Ampere Hour rating, which can be found on its nameplate. For instance, a battery is rated for 200AH or 200 amp-hour of power per day. This number is based on the standard 20 hours of available use. Divide 200 amp-hour by 20 hours, we get the amp rating of the battery, which is 10 amps.

We need to charge this battery at 12 volts and 10 amps, which means you need at least: 12 volts * 10 amps = 120 watts worth of solar panels to properly charge this battery. The rule is to always go up to provide some safety room, so you should get two 100W solar panels. 

3. How much does a 100W solar panel cost?

A standalone 100W solar panel now costs around $100, and you can find models that cost less than $100. That’s for one panel alone. If you want a complete all-in-one kit for the most pain-free installation, it would set you back by $300 and above.

4. What is reverse discharge protection in a solar panel?

Reverse discharge refers to the instances where the electricity that the solar panels produce go back to where it came. The best RV solar battery chargers on the market usually boast a blocking diode to prevent reverse discharge and make sure that electricity flows from high voltage to low voltage, that is from the solar panel to the batteries that need to be topped off.

5. Can I directly charge electronics using solar chargers?

Yes, you can, if your solar kit includes USB ports that allow you to directly connect to electronics like mobile phones and laptops. Make sure you consult your owner’s manual first.

One Response

  1. Mike

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