“How much solar do I need for my RV?” That’s a question we’ve heard repeatedly from RVers considering a move to solar. And we’re always glad to answer because we think RV solar power is fantastic. We’ve spent many years running on solar power, and we absolutely love it. We’re big boondockers, so we’re not tethered to a power pedestal very often. Upgrading our solar array and battery bank over time was among the best investments we’ve made as RVers.
However, there isn’t a blanket answer to provide regarding the size of a solar array needed for the average RVer. That’s because there really isn’t an average RVer. We’re all different, and we travel to different locations. We have different-sized RVs and different types of batteries, and the amount of electricity we use on a daily basis varies widely.
In other words, an RV solar system should be customized to the user. So, in this post, let’s talk about how to determine what makes sense for your solar panel system (and budget).
How Many Solar Panels Do I Need for My RV?
As we just mentioned, RV solar systems should be customized to the user’s needs. There are several ways to calculate these needs, but you must consider various factors based on your particular RVing style. To determine the ideal number of solar panels for your RVing lifestyle, consider factors such as your average daily energy usage and the type of batteries in your battery bank. You’ll also want to consider the square footage of your RV’s interior space, your typical travel destinations, and other factors.
Let’s take a quick look at some of the things you’ll want to consider when planning your RV’s solar power system.
How Big Is Your RV?
The size of your RV and the amount of space you’re looking to heat or cool can impact the amount of solar you need. Generally speaking, a larger RV will have more electrical usage than a smaller one. Appliances will be larger, and there will typically be more lighting, fans, and other gear that uses more power.
Larger RVs definitely have an advantage with lots of roof space for installing solar.
On the other hand, one of the most significant factors a smaller RV will face is having less space on the roof for solar panel installation compared to a larger RV.
What Type of RV Batteries Do You Have?
If you’ve got flooded lead-acid batteries, you can only use 50% of their rated amp-hour capacity before affecting their performance and lifespan. Lithium batteries, however, are designed to allow you to drain them to 80-100% (depending on the brand) without harm. That means that you need to consider both the type AND the number of batteries in your battery bank when calculating your solar needs. They need to be sized to complement each other. After all, what good is a 2,000-watt solar array without the corresponding space to store all the solar energy being captured (the battery bank)?
Where Do You Travel?
The solar power available in April in Tucson will be far higher than in November in Washington. Where you travel makes a difference due to both weather patterns and latitude. When you RV matters too, because of the short winter days versus the long summer days. Luckily, there are online resources available to help give you an idea of how much peak sun your panels will be able to “see” during the day so they can generate power.
Where and when you travel can affect the amount of solar that’s available. The darker the color in this map, the more sun there will be.
What Will Your Panel Angles Be?
Will your solar panels lie flat on your roof, or will you be able to tilt them to optimize their performance? On our old motorhome, we included SolaRVector power tilt systems in our solar installation. They definitely made a dramatic difference, especially in the winter when days are short and the sun stays low in the southern sky. You can read more about this in our post on the actual difference solar panel tilting makes.
You can also take a look at our post, “Should I Tilt My RV Solar Panels?” Tilt kits, such as the SolaRVector Powered Solar Tilt Kit or manual tilt kits (like the example from Renogy below), can make a significant difference if that’s the route you’d like to take.
- Compatible with Renogy Solar Panels under 100W, 100W N-type Solar Panels or 120W Shadowflux Solar Panels.
- Quick assembly with stainless steel fasteners and precise hole placement.
Whether you intend to flat-mount rigid panels, adhere flexible panels to your RV roof, use tilt mounts, deploy portable panels on the ground, or some combination of all of the above will factor into how much power your panels will produce.
Where Do You Tend to Park Your RV When You’re Camping?
If you typically camp in the shade to keep your rig cooler during the dog days of summer, remember that your solar panels will also be parked in the shade (unless you’re using portable panels that can be placed in the sun away from your rig). If forested settings are your favorite places to camp, keep that in mind as you plan your solar array (of course, if you only ever camp in the forest, you might want to reconsider investing anything in solar).
Here we are camping in the forest, looking for the sun! Fortunately, we’re good at conserving power when we’re boondocking in locations where solar power isn’t available.
Note that other items can also shade parts of your solar panels, such as AC shrouds, antennas, and vent covers. Keep these items in mind when planning the location of the panels on your roof.
How Much Solar Can You Afford?
While you’ll want to decide how much to spend on your RV solar system, this question isn’t only about money. You also need to consider how much weight you can afford to add to your rig. Being mindful of your GVWR (Gross Vehicle Weight Rating) and, if you’re towing, the towing & payload capacities of your tow vehicle are also important considerations.
Rigid solar panels will add more weight than flexible panels, but there are other things to consider when deciding what type of solar panels you want. For more on this topic, see our posts on flexible solar panels vs rigid and the benefits of bifacial solar panels for RVs.
What Is Your Daily Average Electricity Usage When You’re Camping?
This is the biggest question to answer, and it’s so comprehensive that it deserves a section all its own. There are several ways to calculate your average daily energy usage while you’re camping. Let’s take a detailed look at how to figure out the amount of electricity you’re likely to need, on average, each day.
How to Calculate Your Average Daily Electricity Usage When Planning Your RV Solar System
The only way to determine how much solar power you need for your RV is to start by calculating your daily average power usage. There are several ways to estimate your power needs and determine how much solar energy is required to meet them. And there’s one way that’s more accurate than the others.
Let’s examine all three options so you can choose the method that suits you best for calculating the solar requirements for your RV.
Use a Generic Solar Guideline Based on Battery Capacity
This is the simplest (though least accurate) method, as it involves using the general guideline of having (in watts of solar) 2-3 times the usable amp-hour capacity of your battery bank. For example:
Let’s say you have 400Ah of total capacity of flooded lead acid batteries. Remember that you should only use (at MOST!) 50% of a lead-acid battery’s capacity to preserve its health and lifespan. This means that with a total capacity of 400Ah, you actually have only 200Ah of usable battery capacity. Using the guideline that you’d want 2-3 times the usable Ah capacity of your battery bank, you’d want between 400 and 600 watts of solar panels.
NOTE: This is one of the many reasons people choose to upgrade to Lithium batteries. Depending on the brand, you can use between 80% and 100% of the rated capacity of a Lithium battery. In addition, they’re lighter… which frees up weight for more solar panels (and other stuff, too). Lithium batteries also have lower resistance to charging, so they charge faster using solar energy.
For example, a Battle Born LiFePO4 deep cycle battery weighs only 31 pounds and has a life expectancy of 3,000-5,000 cycles. They charge very quickly and can be drained down significantly lower than any lead-acid battery on the market without harming them. This means you get more use from a Battle Born LiFePO4 battery on a daily basis… and over time (saving money!).
Battle Born BatteriesBattle Born Batteries harnesses the power of lithium iron phosphate (LiFePO4) to bring you the most efficient, stable, and powerful lithium-ion battery on the market. Whether you're an RV, marine, or off-grid enthusiast, their batteries are built to...Show MoreBattle Born Batteries harnesses the power of lithium iron phosphate (LiFePO4) to bring you the most efficient, stable, and powerful lithium-ion battery on the market. Whether you're an RV, marine, or off-grid enthusiast, their batteries are built to help you get out there and stay out there. Show Less
Power Usage Charts
One way to estimate your daily energy needs is with power usage charts. These provide an estimate of the power consumption of each device and appliance in your rig. You’ll take each number and multiply it by the number of hours you tend to use that device each day. Then, once you’ve got a number for each device and appliance, you’ll add up all those numbers to get the total number of Amp-hours of power you’re likely to use daily.
PRO TIP: Remember that power usage charts provide average (not actual) numbers for each type of appliance. For more accurate information about your RV’s appliances, you can also look at the information label affixed to each appliance for more specific information.
Some pretty neat calculators are available online, like this RV electrical load calculator from Boundless, a solar installer. Their calculator allows you to select an appliance/device and enter the number of hours you typically use it while camping. It then automatically calculates the number of amp-hours per day your battery bank will need to supply to run that appliance or device.
Online tools like this one from Boundless Solar are handy ways to get a rough idea of how much power you use in your RV on a typical day.
Then it asks you where you generally camp. This allows it to calculate gains and losses based on whether you spend most of your time camping in the southwest, where sun exposure is high, or in northern Montana, where there is less exposure. It even calculates DC losses due to the use of 120V AC appliances (any conversion of electricity from one form, 12V DC, to another, 120V AC, involves a loss). Ultimately, it will help you estimate the number of solar panels needed for your expected power usage.
Monitor Your True Power Usage
The most accurate method of determining how much solar power you need is to monitor and measure your RV’s power usage. However, if you want to run your 120V AC appliances (such as your microwave and computers), you’ll need to be able to monitor both your 12V DC power usage and your 120V AC usage.
12V DC Power Usage
For 12V DC power usage, you can install a battery monitor. It will give you accurate readouts for the amount of power you use during a day or for a whole camping trip. For more detailed information, see our posts on RV battery monitors (which covers what they are and how they work).
These are three of the best RV battery monitors available:
The Victron Smartshunt is a single component that broadcasts data to an app on your smartphone. There’s no monitor panel to install, so there are fewer wires to be run during installation.
- ALL-IN-ONE SMART BATTERY MONITOR: The Victron SmartShunt is a smart all in one battery monitor that provides detailed battery insights on your phone....
- DETAILED IN-APP INSIGHTS: Battery monitor data is conveniently presented in the VictronConnect app on your smartphone. Instant readout enables you to...
If you’d rather have a monitor panel that can be viewed without having to rely on an app, the Victron BMV-712 Smart Battery Monitor provides both:
- COMPREHENSIVE BATTERY MONITORING: The Victron Energy BMV-712 Smart Battery Monitor tracks various parameters for battery systems with voltage ranges...
- ADDITIONAL INPUT: Victron Energy BMV-712 features an additional input which can be programmed to measure battery temperature, midpoint voltage, or...
The Xantrex LinkPro Battery Monitor is also a good one to consider:
- Item Package Dimension: 6.5354330642L x 4.4488188931W x 3.3070866108H inches
- Item Package Weight - 0.771617917 Pounds
For more information about the best RV battery monitors, check out this post: 5 Best RV Battery Monitors
120V AC Power Usage
There are several ways to determine your actual 120V AC power usage. You can disconnect from shore power and run your inverter to power your 120V AC needs, allowing power draw to be tracked as 12V DC usage through a battery monitor like those mentioned above.
Alternatively, you can use a kill-a-watt device to monitor the 120V AC power use of one appliance or device at a time.
- Please see the above description.
Finally, you could use a Hughes Power Watchdog in line with your shore power cord. This is the method that we think is the best, as it allows you to monitor all 120V AC power usage at once. However, you do need to be aware that if your inverter doesn’t supply power to all 120V AC appliances (for example, air conditioners or your water heater’s 120V AC heating element), you shouldn’t use those appliances/devices when you’re conducting monitoring/testing. That’s because you won’t be able to run them off your batteries when you’re dry camping anyway.
An advantage of the Hughes Power Watchdog is that it also provides surge protection, which is something you should have on your RV, anyway. Additionally, you can buy one of the models with EPO (Emergency Power Off), which protects your RV against over- and under-voltage conditions. We would never plug our rig into shore power without some form of electrical protection.
Both 30A and 50A models of the Hughes Power Watchdog are available. RVgeeks readers get a 10% discount buying factory-direct from Hughes. MobileMustHave has just announced they’re also carrying Hughes products, and you can get a 5% RVgeeks discount there. Since prices vary, be sure to check Amazon, too!
Make sure your RV is protected from low voltage, bad RV park wiring AND power surges when connecting to shore power with a Power Watchdog and/or Hughes Autoformer. We never hookup without ours (we have both), and know our RV's electrical system...Show More
Make sure your RV is protected from low voltage, bad RV park wiring AND power surges when connecting to shore power with a Power Watchdog and/or Hughes Autoformer. We never hookup without ours (we have both), and know our RV's electrical system and all our electronics are being protected.
Watch our Hughes Autoformer video
Watch our Hughes Power Watchdog video
Save 10% on your entire purchase when ordering from Hughes!
Show Less
Thanks to the latest additions to our RV internet arsenal from MobileMustHave, we're able to stay connected more reliably... and more remotely... than we ever could before. We couldn't be happier with the equipment we now have!
Upgrade...Show More
Thanks to the latest additions to our RV internet arsenal from MobileMustHave, we're able to stay connected more reliably... and more remotely... than we ever could before. We couldn't be happier with the equipment we now have!
Upgrade your RV internet connectivity with great products from Peplink, WeBoost, Parsec, Poynting, Mobile Mark, and more. And while you're there, look at other great products like Viair Compressors!
Watch our video about our RV internet connectivity solutions for 2021
Save 5% on your equipment order at MobileMustHave.com when you click the button on this deal or use discount code "RVGEEKS" at checkout!
Show Less
- Enhanced Safety Alerts: Stay ahead of electrical issues by receiving timely wireless fault alerts, ensuring your camper is always protected from...
- Stay Connected Anywhere: Wifi enabled monitoring keeps you informed of your camper essentials with voltage meter data anytime, anywhere-perfect for...
- Enhanced Safety Alerts: Stay ahead of electrical issues by receiving timely wireless fault alerts, ensuring your camper is always protected from...
- Stay Connected Anywhere: Wifi enabled monitoring keeps you informed of your camper essentials with voltage meter data anytime, anywhere-perfect for...
Figuring Out Your Total Solar Required
Once you know your power usage (in amp-hours), multiply it by 2-3 to get the total watts of solar you need to install. Then divide that number by the wattage output of the panels you plan to install. For example, 400 Watts of solar ÷ 100 Watt panel output = 4 panels needed.
Remember that installing 400W of solar doesn’t mean you’ll get 400W of output. The angle of the sun, weather, the cleanliness of the panels, and any trees or other obstructions all affect performance. And, of course, the time of year is important, with short winter days providing far less opportunity for solar charging.
A Note on Oversizing
With all the concern about having enough solar power to meet your average daily energy usage, it’s important to remember that you don’t want to oversize your system too much. Having enough solar is great, but too much solar can be a waste. If your solar panels completely replenish your battery bank by noon every day, the remainder of the day’s sunshine may not be used since there’s nowhere to store that energy.
Check out our entire series of posts in our “Solar & Batteries” category for lots more information on this popular topic.
Free RVing Tips, Tricks, Reviews & Giveaways
As 20-year full-timers, we share everything we’ve learned about RVing over the years. Join our online community to receive a wealth of great RVing knowledge delivered daily to your inbox.
Whether you’re a new RVer or a seasoned full-timer, you’ll love the wide range of RVing topics we cover. Don’t miss a single article or any of our famous Giveaways. Subscribe to our newsletter today!
Angi Livermore
Friday 21st of June 2024
I have a residential refrigerator. I would also want to run my A/C unit in the summer. Coleman 15k and 13.5k. Not sure how much power these would consume. Do you run your A/C on your batteries?
TheRVgeeks
Friday 21st of June 2024
Hi Angi. Our old 18 cubic foot Samsung residential fridge typically used about 125 amp-hours PER DAY of power from the batteries (running off the inverter). Air conditioners can pull anywhere from about 10-15 amps when they're running... so, depending on how hot & humid it is outside, and how low you set the temperature, the run time each A/C unit will have would vary. The hotter out, and the lower you set the temp, the more often they'll have to cycle on... and the longer they'll have to run to keep it cool... so the more power they'll pull each hour.
In our old Mountain Aire, we didn't have our system wired in a way that allowed us to run the A/C... but on the new trailer we do. And, with all of the heat we've been experiencing, we HAVE run the A/C off of the batteries, which has been a real help at times. But it IS a huge drain and our system isn't large enough that we could run the A/C all day when we're off grid.