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RV Solar Panels: What You Need To Know

(Camp Addict does NOT accept payment from any company to review or endorse their products.)

One of the most popular (and misunderstood) topics talked about amongst RVers is solar power.

Do you need RV solar panels? If so, portable or rooftop RV solar setup?

How much solar power do you need for your RV? What charge controller is the best?

Monocrystalline or Polycrystalline solar panels, on and on, you get the idea.

RV solar panel use is almost an inevitable topic of discussion among RVers. There is a LOT to know.

As full-time RVers and full-time boondockers, Camp Addict Kelly and Marshall have been learning about and using rooftop and portable solar panels for a combined total of 13 years. 

In December 2018, we installed a 600-watt rooftop solar system on Kelly's rig, complete with a solar controller and battery monitor. (No inverter was needed.)

Read on for our very in-depth RV solar panel educational guide.

Ready to go off-grid and get started with RV solar panels? Click the button below to read our portable solar panel reviews.

Your Guide To Everything About RV Solar Panels

There's sooooo much to know when it comes to RV solar panel use, right? Amps, watts, volts, battery controllers.

It's electricity, which is complicated and tricky. It can make you want to pull your hair out!

If you are anything like Camp Addict Marshall, you don't have extra hair to spare. (heh)

So let's teach you what you need to know about solar panels for RV use so that you know what to get and how to use it.

Kelly's portable solar panels deployed

Do You Need An RV Solar Power System?

Not everyone can benefit from an RV solar system. There are a great number of RVers and campers that don't need any kind of RV solar set.

Solar power serves a single purpose - to charge your RV batteries. (When your RV isn't plugged into shore power.)

In other words, it charges when your RV is off the electrical grid (off-grid).

That's it. Simple, right? Well, yes and no.

Technically every RV is "off-grid" a lot of the time. Say, when driving down the road to your next destination.

You aren't trailing an extension cord that is 200 miles long, are you? Nope, you sure aren't.

So you are technically off-the-grid during those times, but you aren't necessarily a candidate for solar power.

Most RVs, whether you have a motorhome, a Class B van conversion, a fifth wheel, or a travel trailer, have batteries that are charged as you drive.

RVs with their own engine have one or more alternators that provide power to the RV house batteries (the batteries that power all the 12-volt systems in your rig).

Trailers (the vast majority of the time) have an 'umbilical cord' that charges from the tow vehicle while driving down the road.

Class C motorhome on California Highway 1

If you always move your RV from campground to campground where you are plugged in, then you likely don't need an RV solar setup.

If you only occasionally camp 'off-grid' (dry camping) you might still not need a solar power system for RV use

You might have enough house battery capacity to make it through a couple of days of use. (Without discharging your lead-acid batteries below 50%.)

Once you are done camping for the weekend, or a few days, you can head home, plug your RV in, and top off your batteries.

The type of camper that benefits the most from RV solar systems is one that boondocks extensively, or boondocks with very little battery capacity.

Take for example Camp Addict Co-Founders Kelly and Marshall. We both boondock exclusively and are ALWAYS unplugged.

While this may change in the future, we still foresee ourselves as boondocking 99% of the time. So, we need RV solar panels to keep our batteries charged.

Otherwise we'd have to run the portable generator all the time, and who wants to listen to generator noise while camping in areas of serenity?

Here's a hint: NOBODY

So, if you are in campgrounds full-time, you can probably live without solar power for RV use, especially if you have a generator.

If you boondock all the time, an RV solar setup will be nice instead of using generators all the time. 

portable solar panel while rig is shaded

Portable Solar Panel (right) Is In Sun While Fixed Solar Panel (on top of RV) Is In Shade

Portable Solar Panels Versus Roof Mounted Solar Panels

Once you've decided you are a candidate for an RV solar system to charge your RV batteries, the next question is what type? Rooftop or portable solar?

There are pros and cons to both approaches.

Keep in mind that a portable solar system maxes out at about 200 watts.

Sure, you can buy multiple portable systems and connect them to a single solar controller. But there comes a point when it becomes a true pain in the behind having a bunch of portable panels strewn about.

Still, it's possible!

If you need a lot of RV solar capacity, you may want to consider having a combination of permanently mounted rooftop panels as well as a portable panel.

rooftop solar installation

Rooftop Solar Panel

Solar panels for RV roof use are the easiest to deal with. They are permanently mounted up on your roof.

You don't have to 'deploy' them at every new campsite. (Also, you can't run them over. LOL!) They are always just there. But they may be overkill for your situation.

However, if you like to tuck your RV amongst the trees for shade, a roof-mounted RV solar system obviously isn't going to produce much solar energy.

Roof Mounted Solar Panels Pros and Cons:

  • Permanently mounted so you don't have to set them out
  • Installed up high, out of the way
  • Don't have to rotate to 'follow' the sunlight
  • Might not have the room on your RV's roof for the installation
  • If you park your RV in the shade to keep it cool, your solar panels aren't going to provide much power
  • You may not need a solar energy source enough to justify the expense of installing a good solar power system on the roof of your rig
  • A solar panel for RV roof setup should be kept clean which means you will frequently have to climb on the roof of your RV to make your solar panels all sparkly

A portable solar system has its place in the RV world. No question about it!

A portable setup is a great way to dip your toes into the world of RV solar power.

It's pretty much the perfect solution for someone who likes to boondock but doesn't need a full-blown roof-mounted RV solar setup.

portable solar installation

Portable Solar Panel

Portable RV Solar Pros and Cons:

  • Great way to enter into the world of using solar energy as a power source
  • Perfect RV solar solution for travel trailers and motorhomes that only occasionally camp off-grid or doesn't have huge 12-volt power requirements
  • You can park your RV in the shade to keep it cooler while your portable panel can be out in the sun
  • You can use a portable setup with multiple rigs - easy to take it with you when you upgrade your RV
  • A portable panel is an ideal compliment to fixed roof mounted RV solar panels, expanding your system capability and giving you better charge capability when the sun is at a low angle
  • You should keep your RV solar panels clean so they harvest solar energy at peak efficiency, and ground deploy panels are a heck of a lot easier to clean than a roof mounted RV solar system
  • You have to 'deploy' the panel on the ground whenever you set up a campsite
  • You need to occasionally (throughout the day) turn the portable panel towards the sun, or your solar energy production will greatly suffer
  • Portable setups are more expensive when you compare them watt-to-watt to a solar system for RV roof installation
  • You have to remember that there is a solar array on the ground as you are walking around at night. Ask Camp Addict Co-Founder Kelly how she learned this lesson. (Marshall may have fallen victim as well, and it may have still have been semi-light outside.)

If you don't think you are going to need much solar power, or you cannot justify installing roof-mounted RV solar panels, a portable system is a great option. 

They also are a great way to expand an existing roof-mounted RV solar panel system (and give you a bit more flexibility as far as where you can park your RV).

Camp Addict Co-Founder Marshall purchased his Lance travel trailer with a factory-installed 160-watt roof mounted RV solar panel system.

Once he started boondocking, it became clear that a larger solar energy source was necessary.

Rather than install another roof-mounted RV solar panel, he opted to go with a portable 100-watt solar panel system that is 'ground deployed'.

Why?

A couple reasons:

  1. The sun in the winter is fairly low, and a flat roof-mounted RV solar panel doesn't provide as much solar energy production in the winter as it does during the summer. Having a ground deployed panel that is tilt-able and can be pointed directly at the sun at the optimal angle is a very good thing (unless you've got a bunch of space and disposable money to put a lot of RV solar panels on your roof).
  2. The ability to park his travel trailer where he wanted without worrying too much about shading the roof-mounted RV solar panel is a good thing. There are times when the perfect shade tree appears and will provide relief from the harsh afternoon sun but will shade the rooftop solar panel. Having a ground deployed, portable solar panel means the trailer can be shaded in the afternoon, yet the house batteries are still getting charged. Win-win!
poly vs mono solar cell color

Kelly's Old Solar Setup

Camp Addict Co-Founder Kelly has used portable panels in the past without having a roof mounted RV solar system.

This RV solar setup served her well for a few years, even though it was a huge pain in her but to deal with two sets of ground deploy solar panels.

They usually were enough to keep her batteries topped off. Unless it was cloudy.

In December 2018, Kelly and Marshall installed 600-watts of solar on her roof, followed shortly by a couple of lithium batteries.

Gone are her days of dealing with RV solar panels on the ground or worrying about if her power supply would last if there is a cloudy day or two in the forecast.

How Much Solar Power Do I Need For My RV?

The 10 million dollar question is 'how much solar power do I need for my RV'?

How many watts of solar power does an RV need in order to have enough solar energy coming in to both charge the RV batteries and be a power source for energy used during the day?

The short answer is: It depends. (So freaking annoying, right???)

Ask 100 people online how much large of an RV solar system you should get and then sit back, grab some popcorn, and enjoy the show.

This is an area where some people are incredibly educated opinionated.

How large should a solar system for RV use be? There is no easy answer to this question.

There are SO MANY factors that come into play when it comes to how much solar energy capacity you need.

For example, temperature is a HUGE factor in how much usable capacity you will get from your RV's house battery bank. Let us explain.

Lead-acid batteries (most commonly used for RVs) are rated to have a certain amp-hour capacity - that much is pretty common knowledge.

What ISN'T common knowledge is that batteries are rated at X amp-hour capacity at a certain temperature - normally about 77ºF (25ºC).

Any deviation from that temperature and you will have a battery will have a shorter life span (if too hot), or if temps are colder than the optimal temperature, you will have a lower usable amp-hour capacity (but battery life will increase).

Now you see why RVers love chasing the perfect 74º temperature, haha. 

Battery capacity has a fairly linear relationship to the outside air temperature (and therefore, battery temperature):

  • Batteries do not like heat. As it turns out, each 15ºF rise in temperate above the optimal 77ºF temperature will result in a halving of the batteries' life, though capacity will increase by 10%.
  • On the flip side, batteries love cold as far as their lifespan is considered, but not so much when it comes to usable amp-hour capacity. Every 15ºF decrease in temp below the optimal 77ºF results in a 10% decrease in capacity (but battery life increases).

So what happens is that when you need battery capacity the most, i.e. when it's freezing outside and you need to run the power-hungry furnace a lot, your battery capacity will be significantly reduced.

You won't get as much time between charges.

Test At Different Temperatures

Why does all this temperature talk matter?

Because the easiest way to figure out how much RV solar energy production capacity you might need is to go out and camp off-grid.

In other words, use your RV's 12-volt electrical system just as you normally would, but don't be plugged into shore power, a generator, or an RV solar system (assuming you have one).

Depending on what time of the year you do this test, and the outside temperature, you will get different results.

So this is only a rough estimate at best.

Figure Out Your Amp-Hour Consumption

The first thing you need to know is the amp-hour rating of your batteries. How do you find it?

Well, you would hope it would be listed on the battery, but this is often not the case. 

Here's how to find out the amp-hours:

First, You Need To Know 2 Things:

  1. If your battery bank consists of 12-volt or 6-volt battery(ies).
  2. What the amp-hour rating of each battery is.

Find Your Battery Maker and Part Number

Start by looking at your battery label. It might be located on the top, OR the side of your battery(ies).

It will list who made it and the battery part number.

Most likely the label will not have any information about the voltage of the battery or the amp-hour rating. Therefore, you have to search for it on the internet.

Centennial Battery Systems label

This Label Does Not Show Us The Specs We Are Looking For (No Ah @ 20 hr Rating)

Enter the manufacturer and part number into Google. This should take you to some sort of battery specification page.

It will tell you the voltage and the amp-hour rating.

Look for the amp-hour rating at 20 hours of use (abbreviated as 'Ah @ 20hr' or '20HR rating' or something similar).

This is the industry standard number that people are referring to when they are talking about the amp-hour rating of a battery’s capacity.

Example: Using the Centennial Battery label above as an example, we enter 'centennial battery dc24mf' into Google and find this battery information page with the information we are looking for (look through the information to find what you are looking for): 12-volt and 75 amp-hours!

Finding Total Amp-Hours For Your Battery Bank

One battery: Easy. If you only have one, your amp-hour rating is the Ah @ 20hr rating stated on the battery spec page.

Multiple Batteries: If you have multiple batteries (we will use two batteries for our explanation purpose), then you have some figuring out to do.

First, you need to know if your batteries are connected in series or parallel. This step is pretty easy once you know if you have 12-volt or 6-volt batteries.

A battery bank consisting of two 12-volt batteries will be wired in parallel, while two 6-volt batteries will be wired in series.

This is always the case when you have two batteries.

Now to calculate the battery bank’s amp-hour rating.

  • Batteries connected in series will increase (double) the voltage of the batteries but the amp-hour rating will remain the same. Batteries connected in parallel will increase (double) the amp-hour rating but the voltage will remain the same.
  • Example: Two 6-volt batteries rated at 210 amp-hours each connected in series will result in an overall voltage of 12 volts with a 210 amp-hour rating. Two 12-volt batteries with a 75 amp-hour rating each that are connected in parallel will result in an overall voltage of 12 volts but an amp-hour rating of 150.

Continuing to use our example of the Centennial Battery, we found out that the part number DC24MF is a 12-volt battery with a rating of 75 amp-hours (Ah @ 20hr).

With a 2 battery system (that we know is wired in parallel because of the above point), we can calculate that the overall system voltage remains at 12-volts, but the amp-hour rating is doubled to 150 amp-hours (75 amp-hours x 2).

Amp-Hour Consumption

  • The most accurate way to measure your energy consumption is by using a battery monitor. Of course, this requires buying, and installing, an instrument. To learn how to get a rough estimate of power consumption, read on.

Here's what you need to do to get a rough estimate as to your daily amp-hour power consumption:

  • Know how many amp-hours your RV's battery bank is rated for (remember that this will be at the 'perfect' outside temperate of approximately 77ºF).
  • Go camping somewhere that you aren't plugged into ANY source of power. This includes any RV solar system that you might have.
  • Use your RVs 12-volt electrical system as you normally would. Don't try to conserve. Don't try to be a power hog. Just be 'normal'.
  • At the end of the first 24-hour period, check your battery voltage. You may have gauge inside of your rig that tells you the voltage, but the more accurate way to do this is to take a multimeter and measure the voltage directly at the battery bank (see below video). Use the below chart to see what state of charge percentage the measured voltage corresponds to.
12 volt battery state of charge chart

How To Check Your Battery Voltage With A Multimeter

  • If, after the first 24 hours of normal use, your battery bank still has sufficient capacity left for another day of use, go for it! Continue to use your RV's 12-volt systems as you normally would. Take another reading after the second 24 hour period and see what percentage of full charge your batteries are at.
  • Continue to use your RVs batteries until you get to around 50% charge. Figure out how many days that took. Assuming you ended up somewhere in the neighborhood of taking your batteries down to 50% charge, you can divide your batteries' rated amp-hour capacity by 2 and come up with how many amp-hours you used over the test period. Divide the amp-hours used by the number of days in the test to get a per day amp-hour usage. For example, say you have a 200 amp-hour battery bank and it took 3 days to use 50% of the rated capacity (100 amp-hours). 100 divided by 3 is 33 amp-hours used each day. Boom! You've got a ballpark number.

Temperature Matters

Testing your batteries is where outside temperature comes into play.

Ideally, you will want to do this test when the outside temperature is 77ºF, but good luck with that. Days will be hotter than nights.

You may do this test in the dead of winter in some cold location and never see anywhere close to 77ºF, even during the day.

So, yeah, this test has some flaws, but without springing for a fancy battery monitor, this is as good as we get if you want an easy way to guesstimate how much power you use.

Now that you have a (very) rough idea of how many amp-hours of electricity you use per day, it's time to figure out how much solar you need.

Here we go with another 'rule of thumb'. A 100-watt solar panel will generate approximately 30 amp-hours per day.

Using our fake test data from above (33 amp-hours consumed on average per day), we can get an idea of a good starting point for pondering how much RV solar energy capacity you need.

50% Rule

With lead-acid batteries (the most common type used in RVs) you NEVER want to go below 50% charge.

While the above chart indicates that 40% charge is still 'in the green', try not to go below 50% state of charge.

Your RV batteries will love you for this and will reward you by having a long, healthy life.

Since a 100-watt RV solar panel will produce somewhere in the neighborhood of 30 amp-hours per day, it won't be enough capacity for our sample RVer.

So that means you are looking at at least a 120-watt RV solar panel kit, but in this scenario, you'd be smarter to purchase a 160-watt or even a 200-watt RV solar panel system.

Why would you want to buy more solar than you calculated you need? If you have cloud coverage, your RV solar isn't going to produce anywhere near it's rated output.

So having an excess of solar energy producing capacity on cloudy days is a good thing.

Though, you probably will not have enough RV solar panels to make up for truly bad weather.

Marshall does not have this kind of excess solar energy production capability, so after a string of crappy solar days, it's time to pull out the portable generator.

Kelly is able to get by fine when faced with a couple of crappy solar production days with her 600-watts of RV solar panels on her roof, as well as her lithium batteries (it helps she doesn't use a lot of power overall per day).

Generator and Solar

Sometimes Solar Isn't Enough And You Have To Use A Generator

If you only camp where it's beautiful weather all the time (please excuse us as we laugh uncontrollably at the idea of the perfect camping weather all the time), then clouds aren't a thing that you need to worry about.

If you are like the rest of us and live on planet Earth, you need to consider having excess RV solar energy capability.

This most likely means you will need a decent number of RV solar panels on the roof and might supplement it with a ground solar panel. 

You can start out with a portable solar system and see how well it fits into your style of camping and power usage.

You can later add RV solar panels to your roof should you find that your initial ground deploy solar panel purchase isn't enough (which most likely will be the case).

Polycrystalline or Monocrystalline Solar Panels?

RV solar panels comes with one of two types of solar cells:

  • Polycrystalline
  • Monocrystalline

The difference between polycrystalline (poly) and monocrystalline (mono) solar panel cells is how they are made.

Monocrystalline is more expensive but more efficient.

Poly solar panel cells are the cheaper of the two, are slightly less efficient than mono cells, and are made by many silicone crystals/fragments that are melted to form a larger 'wafer'.

Mono solar cells are cut from a single silicone ingot and are smaller sized than poly when you are comparing same solar energy production capability (watts).

Individual mono cells have a distinctive square with cut-off corners appearance.

poly solar cell

Polycrystalline Solar Cells

mono solar cells

Monocrystalline Solar Cells

A poly solar cell system is somewhere in the neighborhood of 13-16% efficient.

A mono solar cell system runs in the range of 15-20% efficiency. 

Most quality RV solar panels are made from monocrystalline (mono) solar cells because of the greater efficiency of a mono cell system.

This results in a smaller overall size for a given wattage, therefore taking up less roof space (in the case of roof mounted solar panels) or storage space (in the case of ground deploy solar panels). Plus they are lighter (again, for a given wattage of solar energy production).

Poly Solar Cell Pros And Cons:

  • Cheaper than a mono solar panels
  • Blue-ish in color
  • Larger sized than a comparable mono cell solar power system
  • Less efficient in converting sunlight to solar energy (though you may not really notice the difference)

Mono Solar Cell Pros And Cons:

  • Most efficient in converting sunlight to solar energy (though the difference can be negligible)
  • Smaller sized than a comparable poly solar panels
  • Blackish in color
  • Higher priced

So what type of solar power system for RV use do you purchase?

Monocrystalline or polycrystalline? The best RV solar panels come with mono cells.

The cheap RV solar systems most likely come with poly cells, though as far as roof top setups, these are becoming increasingly uncommon.

With portable setups the poly solar panel systems also come with crappy solar controllers, undersized wiring, and a cheaply made frame and leg setup.

When it comes to lightweight options (weight is critical in many RVs) and roof space (also a major consideration for roof top setups) we recommend monocrystalline RV solar panels.

poly vs mono solar cell

Poly (right) vs Mono (left) Solar Cell Color

Solar Charge Controllers Explained

Solar charge controllers regulate the amount of voltage that gets transferred from the RV solar panels to the house batteries. The charge controller will 'read' what voltage the batteries are at.

Then they will change the voltage that is going into the batteries from the solar panels depending on the current state of charge.

Types Of Solar Charge Controllers

Charge controllers come in two 'flavors' - PWM (pulse width modulation) and MPPT (maximum power point tracking).

PWM controllers are less efficient, but are also cheaper than MPPT controllers.

PWM controllers are what come with portable panels, as well as most factory RV solar panel installations, so they will be what we concentrate on here.

A PWM charge controller isn't very efficient in converting the incoming solar energy (sunlight) from the solar panels to be used as available power to the batteries (they are in the range of 75-80% efficient, whereas an MPPT controller is 94-98% efficient).

This is because a PWM solar controller is basically just taking the incoming voltage from the RV solar panels and reducing it to the level that the batteries will accept (without overcharging them).

Doing so causes a reduction in available power from the solar panels.

(There is a 'fancy' formula for this calculation, but unless you are a total geek, it'll most likely just cause your eyes to glaze over.)

When you are dealing with lower wattage systems, such as a typical portable setup, or most roof top factory installations, living with this inefficiency is a tradeoff to keep the overall price lower by not going with a considerably more expensive MPPT solar controller.

As RV solar power system sizes (overall wattage) grow, then the inefficiencies of a PWM controller become much more noticeable and MPPT controllers are generally used (as the controller, while more expensive, will be a much smaller percentage of total system cost).

PWM Solar Charge Controller in use

PWM Solar Controller That Isn't Waterproof

Solar Controller Charge Stages

A solar controller will have a certain number of charge stages, where a stage is the actual voltage that is being used to charge the RV batteries.

There are three basic stages (also known as a 3-stage charger):

  1. Bulk charge - 100% of available power from the RV solar panels is used to charge the batteries until the absorption voltage is reached (generally 14.4 to 14.6 volts).
  2. Absorption charge - Once a set voltage is reached (normally in the 14.4 to 14.6-volt range), the charge controller will switch to the absorption stage. At this point, the battery is charged to somewhere in the neighborhood of 85% of full charge. The solar charge controller will then maintain the absorption voltage (again, typically 14.4 to 14.6 volts) for a set time (1 to 2 hours). Both voltage and time period varies depending on the solar controller manufacturer.
  3. Float charge - After the absorption charge 'session' is complete, your RVs batteryies are pretty close to fully charged. The solar controller will bump down the battery charge voltage to a range of 13.2 to 13.7 volts (each manufacturer is different) and hold this for the duration of the time sunlight is hitting the solar panels. This lower charge voltage will ensure that the batteries aren't overcharged and that the battery acid isn't boiled off. If there is an excessive load on the batteries and the controller is no longer able to maintain the battery charge level at the float charge point, it may 'kick' back into bulk charge mode, increasing the voltage to the batteries (and bring the batteries back up to fully charged, assuming there is enough solar energy output to do this).

While the above charge modes are what every PWM solar charge controller has in order to effectively charge batteries, there is another mode called equalization.

This used to just be called 'equalizing the batteries' but someone who has a fancy marketing degree decided to call this a fourth charging mode (because 4 is better than 3, right?).

Equalizing mode charges the batteries somewhere in the range of 14.8 to 15.5 volts (manufacturer dependent), which essentially overcharges the batteries causing gassing of the battery cells.

This serves the purpose of making sure that all cells of a battery bank have the same charge.

Generally, equalization is set to run every 4 weeks, though some controllers will automatically kick into equalization mode if the battery bank voltage drops below a certain level (typically 10 - 12.1 volts which is a wide range, but again different manufacturers have different ideas and they probably all think they are right).

Only flooded wet cell lead-acid batteries should be equalized (unless your AGM or gel lead-acid battery manufacturer says go for it).

Solar Charge Controller Displays

Decent RV solar charge controllers will have an LCD/digital display that will show you what is happening with the controller and batteries.

It tells you voltages, amperage, power usage, and probably more information than you care about.

They will also have LEDs that indicate charge modes, faults, or other gee-whiz details.

Solar controllers that come with inexpensive portable solar kits will only have LEDs, so they aren't of much use. But at least they will charge your RV's batteries (in theory), right?

Able To Monitor Your RV Battery?

Another consideration of the solar charge controller is whether or not it has the ability to directly monitor the battery bank voltage and/or temperature.

Monitoring of the battery 'vitals' helps prevent damage from overheating and overcharging.

The ability to remotely monitor the batteries is nice to have.

However, plenty of people have lived without this ability for many years and probably will tell you their batteries did just fine.

Solar Charge Controller Battery Type Compatibility

The solar charge controllers that come with portable solar panel kits are compatible with flooded, gel, and AGM style lead-acid batteries.

If you have lithium batteries in your RV (awesome deal if you do!) then you will need to use a different type of solar controller - one that is compatible with lithium batteries.

Of course, you most likely will have a pretty massive RV solar array that has an awesome MPPT solar controller if you've gone the lithium route, cuz you are probably somewhat of a power/solar geek.

Battery Monitors

Figuring out how much power you use, and therefore how much solar capacity you need, can be a bit of a black art.

There are so many variables - day to day variance of electrical use, cloud cover that reduces solar energy input, the outside temperature, etc, etc, etc.

One way to see exactly how much power is going into, and out of, your RV's battery bank is to use a battery monitor.

This precisely measures the amount of electrical current flow in and out of your batteries.

If you want to get a truly accurate picture of how much RV solar energy production capacity you need to keep up with your power usage, then a battery monitor is a must-have accessory.

The Victron BMV-712 is a popular choice as it is relatively inexpensive.

It comes with Bluetooth capability that lets the monitor communicate with a smartphone app (both iOS and Android).

This way you can easily see what your batteries are doing.

(You can view information directly from the monitor, but the app makes it much easier.)

Victron BMV-712 Battery Monitor

Victron BMV-700 battery monitor

Victron Battery Monitor

Victron iOS app

Victron iOS App

Why not use a cheap plug-in battery monitor like that pictured below?

Because it doesn't keep track of the amperage used.

It only measures system voltage at the 12-volt outlet that you have it plugged into (measuring directly at the battery is far more accurate as there is no voltage drop due to the RV's wiring).

You need to use a TRUE battery monitor like the BMV-712 above to accurately track how much power (amp-hours) you use and therefore know how much solar capacity you should purchase.

Innova battery monitor

Not What You Want To Use

Conclusion

Solar panels are a fantastic way to keep your RV powered and your batteries charged. What you get will depend on your particular power usage and needs. 

You should have a pretty good understanding now of the basic concepts of RV solar and the pros and cons of a portable setup versus roof top RV solar panels.

RV solar can be a game changer for many RVers, especially boondockers or people wanting to break their dependance from staying at RV parks.

Whether or not you think RV solar power is right for your style of camping, at least now you have a general idea of what is involved in harnessing this abundant power source from the sun.

Kelly Headshot
Kelly Beasley

He-llllo. I'm the co-founder of Camp Addict, which my biz partner and I launched in 2017. I frigging love the RVing lifestyle but in December of 2020, I converted to part-time RV life. Heck, I lived in my travel trailer for over 5.5 years, STRICTLY boondocking for pretty much all of it. Boondocking is a GREAT way to live, but it's not easy. Anyway, I'm passionate about animals, can't stand campgrounds, I hardly ever cook, and I love a good dance party. Currently, I can be found plotting and scheming whether or not to start collecting farm animals (or plotting my next RV trip!) at my beautiful new 'ranch' named 'Hotel Kellyfornia', in Southern Arizona.


Marshall Headshot
Marshall Wendler

Camp Addict co-founder Marshall Wendler brings his technical expertise to help explain RV products in an easy to understand fashion. Full-time RVing from April 2014 - December 2020 (now RVing about 50% of the time), Marshall loves sharing his knowledge of the RV lifestyle. Marshall spends the majority of his RVing life boondocking. He is the part of Camp Addict that knows 'all the things'. He's good at sharing his technical knowledge so you can benefit. 

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  • Good explanation of solar options. My answer to the question of how much do I need will always be how much can I fit on my roof.

    • Hi Noah,

      LOL! Yeah, there’s almost no such thing as ‘too much solar’. I have the 600 watts, and it seems like overkill. However, what if I went to the PNW and it was not sunny for 5 days? I might be in trouble on day 4 in such a case. I can easily use about 10% overnight. Then charging my MacBook Pro certainly eats up a lot of amp-hours. So, with two lithiums and 600 watts, I am fine out in the sunny southwest. However, there are times when I could come close to totally discharging them.

      We say more is always better in the case of RV solar.

  • Can you tell me if I can install a high amp solar panels to my 2012 Roadtrek 210 with two AGM Trojan batteries. I’m looking to keep my fridge running on twelve volt power and maybe small interior things while I’m parked in a hotel parking lot or anywhere else and not have to worry about dead battery’s. May wind up doing a lot of boon docking also. Thank you ted. Portable would be nice but would certain to be stolen left unattended.

    • Hi Ted,

      I agree that portable solar panels aren’t the way to go in your situation. They would be a great theft target when you are parked in a parking lot.

      I don’t believe there is much rooftop space on a Roadtrek 210, but I’m not familiar with how much space is up there. It should be possible to put some sort of solar system up there. The question is, how many watts can you put on the roof (how much room is there)?

      You may want to talk to someone familiar with doing installs on Class B motorhomes. I don’t know anyone off the top of my head, though our friend Dan does solar consulting and he may be better equipped to answer this question.

  • Nice article. Thank you.

    This Montana winter of Covid is one of contemplation, and I am restless.

    I have a small travel trailer that we have outfitted with a 100 amp hour AGM battery. We have reworked much of the electrical to update our “hard sided tent with a bathroom”, and upgrades include a 100 watt solar suitcase with an exterior port to plug it in. We have a 700 watt Inverter. All of this is run through a distribution bar, not lots of wires run to the battery terminals. It all works great. I can go 3 or 4 days without a recharge if I wanted (we tend to top off even daily).

    I don’t deploy my solar panels unless we are in camp. I have this idea that I could mount a 50 watt solar panel on the roof and it could act as a battery maintainer and small recovery on a daily basis without us being present. It would have a separate controller from the solar suitcase, and be wired through the distribution bar like everything else. Of course the trailer is usually parked to take advantage of afternoon shade if available.

    Would this work? Also, never in 3 years has this been necessary.

    Glad I found your web page, it’s fun to find a kindred spirit about using solar.

    • Hey Gregory!

      Glad you found Camp Addict also!

      Sure, you can certainly do that (have a 50-watt solar roof mounted solar panel running through its own solar controller). In fact, that’s what I essentially had when I first got my solar suitcase. Except my roof mounted solar was the factory installed 160–watt panel and the ground deploy was the same size you have (100 watts).

      I initially had the two solar panels running through their own controller (with the solar suitcase’s controller hooked directly up to the batteries), but I found that they would end up fighting. One would go to float mode prematurely based on the other one’s output voltage. Or something like that. It’s been years so I don’t remember the exact details. I just know that they didn’t play nicely with each other, so essentially I’d have one off-line much of the time. Not doing anything.

      So I ended up wiring the ground deploy directly to the hard mounted solar controller that came from the factory. Solved the problem! You might want to consider using a single controller for both panels, if you chose to do this.

      However, if you do use a single charge controller for the two panel setups, you have to be mindful of the output voltage and amperage of the two panels. If they aren’t ‘matched’, then one will ‘drop down’ to the output of the other one (either the voltage or the amperage, depending on if you have them wired in series or parallel). It’s a bit of a confusing concept to wrap your mind around, but it is important to be aware of the need to match solar panels in a system (using the same charge controller).

      I discuss this more in the 2-part article series where I discuss the solar install we did on Kelly’s rig a couple of years ago. I’ve also done a very similar setup on my rig (did it this past June) where I added 600 watts on the roof, a new charge controller, and two lithium batteries. I didn’t do a series on my install since it was done in pretty much the same way we did Kelly’s, so it would be redundant. Only difference is where I mounted the equipment inside the rig.

      But, like you said, you haven’t needed roof top solar in 3 years, so all of this could just be a thought exercise. But let me tell you, when you are living in your rig full-time (not your case), having plenty of solar and batteries is a game changer. I’m a bit irritated it took me so long. Oh well! Live and learn.

    • Hi Jim,

      I’m glad you liked this article on RV solar panels and that it provided information you were looking for.

      Thanks for checking out Camp Addict!

      • Hi Marshall,

        Thanks for your reply. To be brief, there sure is a lot of information out there, and some of it can not be right.

        I would like to go ahead with my project, but the controllers fight has my attention. The trailer gets charge from my tow vehicle when I travel, the solar suitcase when I want to fully recharge during camp outs. These are controlled. So what if I installed a breaker between the roof solar panel and the controller? That way I could also have full control as to when I wanted the roof panel to be online. That way I wouldn’t have two charge controllers fighting each other, or have the converter charger and the solar panel having conflict (though I have no idea if that would be a problem).

        I wonder how many people are out there trying to update to solar that are feeling there way in and have to learn the hard way?

        • Hi Gregory,

          I wouldn’t worry about any conflict between the roof top controller and the tow vehicle trying to charge the battery (or converter charger trying to charge the battery). This isn’t an issue that I’ve ever run into, or have ever heard about.

          As far as having the rooftop controller and the solar suitcase controller fighting each other, just try and see what happens. Observe how the two controllers interact. May not be an issue for you. Nothing will get damaged. The system just may not be as efficient as it should be. But, again, there will be no electrical damage done (assuming everything is wired up properly to start with).

          Regarding the circuit breaker between the rooftop solar and the solar controller – a properly designed system should have this already. Or, at the very least, a fuse. There should be someway to electrically ‘disconnect’ the solar panels from the solar controller. Larger systems most likely use a circuit breaker. My single 160 watt panel installed at the factory had an inline fuse (that was a real pain to get to – a circuit breaker would have been a lot nicer, but is more expensive).

          It’s really easy to get confused about this stuff. I know it happens to me and I had to go over stuff again and again when I was designing Kelly’s and my systems. This stuff makes my head spin, so I get it.

          If you want to talk to someone that really knows their stuff, our friend Dan does solar consulting and knows this stuff much better than I. Though I don’t think this is necessary in your case. If I were you, I’d just wire up a simple solar system like you are thinking about. Make sure everything is connected properly. And see what happens. As long as the wires are properly fused (or have circuit breakers), the worse thing that should happen is some fuses blowing. Just make sure things are wired properly (I know I sound like a broken record here) and you’ll be fine.

          • Thanks Marshall,

            I would of course at least fuse all of the system if needed, but the controllers are fused. I used some of your recommendations to get a better look, and came to the exact advice you have given me. I will just put it in, and see what happens. I actually think that if the controllers are in a conflict, the solar suitcase will just take over as it will be situated to to deliver the strongest charge. When I install the roof panel, I will leave a spot to insert an in line breaker if it is necessary. I used and in line breaker when I put in an inverter (so my bride of 50 years could have real toast for breakfast…), and that works perfectly.

            Sure is nice to be able to bounce ideas off people who have had more experience than I have, and are willing to pay it forward.

            Happy trails.
            Greg

          • Sounds like you definitely have it under control, Greg!

            Glad we can help. While we certainly don’t know it all, Kelly and I have seen our fair share of RVing adventures and are really glad we are in a situation where we can spread what knowledge we do have.

            Happy adventuring and I hope solar works out for you as well as it has for us!

  • Hi guys,
    I’m a newbie and recently purchased a 2017 Aliner Ranger 10 and used your great advice on how to use the Zamp port for a Renogy 100 W solar panel suitcase and it works great. Then discovered the battery was toast! Do you have recommendations for brand/type of battery? Sorry if I missed it! Diane

    • Hey Diane,

      Welcome to the world of RVing! Glad our advice worked. Whew! 🙂

      You haven’t missed anything about battery recommendations as we haven’t done that yet. So, yeah, batteries…

      How much do you want to spend? Lithium would be the way to go if your pockets are deeper and you will actually be making use of the battery(ies) a lot. They require less care and don’t need to be topped off every day in order to have a long life. But they are still pricey.

      When it comes to lead-acid batteries (the ‘normal’ type that have been around forever), try Costco. I’m running two 6-volt Costco golf cart batteries wired in series. Combined they put out 12 volts (Kelly has two lithium batteries).

      If you only use one battery, I’m pretty sure Costco has 12-volt batteries that would work for RV use. They sell the Interstate Brand, which is pretty decent.

      Trojan is another well known RV brand of lead-acid batteries. They cost more, but are better quality, etc. But with Costco’s stellar warranty (anything happens to the battery in the first year, they will replace no questions asked) and low price, you can buy two or more sets of batteries from them for the price of one set of Trojans.

      We really do need to create a definitive guide to RV batteries and will one day. It’s definitely on the list, but it’s gonna be a doozy to make. So we’re dragging our feet.

      Thanks for the question and we hope you have a blast RVing!

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