How Much Solar Power Do I Need For My RV?

We get it—upgrading your RV or camper with solar power is a big decision. You're looking at the dozens of panels available, and the choice is overwhelming. How much power do you need? How many panels, and what size? What can you run on solar?If you've asked yourself any of these questions, or if you've done some research and found the technical explanations of volts/watts/amp-hours clear as mud, we're here to help clear things up and help you find the best solar setup for your camping needs.If you're still on the fence about a solar investment, check out our article, 4 Reasons Not to Use Solar Power in Your RV (And 4 Reasons You Should), to get a better idea if solar power is for you.
Solar power comes down balancing the two main parts of the power equation:
  • Power Used: (the amp-hours you use each day)
  • Power Stored: (the energy your solar panels provide to your battery)
For help determining how to do this, read on below.
Watch Now: How Much Solar Power Do You Need?

Power Used: How Much Power Do I Need for Camping?

It's important to go into your solar power setup knowing what you need (and what you don't). You can plaster every inch of your camper with solar panels, but this is ultimately a waste of money if you have nowhere to store all the energy the panels produce. On the other hand, underestimating the number of panels you need can mean running out of power or being forced to use your generator when you'd rather avoid it.If you find that your battery doesn't last as long as you need it to, you can add to your battery bank to increase your capacity. It's important to check your camper's size and weight capacity when adding additional batteries.So how much battery capacity do you need? To determine this, you need to calculate how much energy you use in a day. There are a couple of ways to do so.
How Much Power Do I Need for Camping - Infographic
Reading Your RV Battery: How Much Power Is Left?Figuring out how much energy you use in a day means looking at your battery and determining how charged (or not) it is. You never want to drain your lead acid battery lower than 50%, as this can damage the battery and shorten its lifespan. Monitoring your battery sounds pretty simple until you realize stock RV battery voltmeters don't provide the most helpful information. If you have one of these, you'll see numbers like "12.6," or "12.3," which tell you pretty much nothing if you don't know what you're looking at. Basically, a fully charged RV battery will put out about 12.6+ volts. An RV battery at 50% battery will put out between 12.06-12.10 volts, on average. If your voltmeter has a number below this, charge your battery immediately. If you're going to be boondocking a lot, however, it's definitely worth investing in a decent battery monitor or gauge if your RV didn't come with one. There are a lot out there, ranging from very simple models to state-of-the-art battery management systems. At the least, you want to look for a system that will provide a simple charge percentage indication. It's a lot more straightforward to simply have your monitor tell you your batteries are at 80% than to try to figure out what 12.4 on the voltmeter means. Once you know how much power is actually left in your RV (either by checking the voltmeter or by reading the battery monitoring system), you can use this information to determine how much energy you use per day using one of the two methods below.
Redarc Manager30 Battery Monitoring System
Pictured: Battery information provided by the REDARC MANAGER30 battery monitor.

Method 1: Do the Math

This is most people's least preferred method. It involves estimating your daily power consumption while RVing, adding up the total, and using the sum to determine how many solar panels you need. There are dozens of calculators and printable sheets online for this purpose, most of which look something like this:
Calculate Watts Used Per Day
The problem with this method is that you're left to estimate how many watts your appliances use and how many hours a day you use them. Most of us don't walk around our campers with a stopwatch and time how long it takes us to fix a cup of coffee, or use our hair dryers, or charge our phones. These numbers can also vary. Maybe you usually watch an hour of television a day, except if it's raining, in which case you may spend the better part of an afternoon watching movies in your RV. Even if you find the wattage stamped on your appliances, or if you take a reading with a battery monitoring kit, you'll still have to estimate how many hours you're using your items each day.All things considered, this just isn't the most accurate or reliable method for determing how much power you use.

Method 2: The Camping Test

The best way to figure out how much energy you output is to actually go camping. (This is also more fun than a spreadsheet.) If you can make multiple camping trips, even better. Follow these simple steps to determine how much power, on average, you consume in a day:Step 1: Settle out in the boondocks for a couple of days and use your RV as you normally would—don't try to conserve power any more than you usually would, and don't use your generator. Just camp normally.Step 2: Use your voltmeter or a battery monitor to keep track of your battery level. Note that lead-acid batteries should never be discharged below 50%. Going below this mark will shorten the battery's lifespan. Step 3: Do the math to determine how much power you typically consume in a day. Let's say after two days, your 200 amp-hour lead-acid batteries are at 50%. This means you used 100 amp-hours in two days, or 50 amp-hours a day. NOTE: If you can't even make it through a day without draining your battery, consider adding to your RV's battery bank. All the solar panels in the world won't help if you don't have enough battery capacity to store the power you require. Ideally, you should be able to go at least 2-3 days before your battery is depleted.
Energy Saving TipsWhen boondocking, it helps to get in the habit of conserving energy. Try these tips below:
  • Use LED bulbs
  • Unplug electronics when not in use (phones, tablets, etc.), or charge them while driving if possible
  • Adjust your daily routine - read during daylight hours, vacate the camper during the day instead of using fans, etc.
  • Replace older TVs with efficient, LED flat screens
  • Shorten your shower time
  • Park under shady trees or use your awning to keep cool; conversely, layer up to keep warm

Power Stored: How Many Solar Panels Do I Need for Camping?

So now that we know how solar power works and how much power we need per day, we can ask ourselves the big question: how many solar panels do we actually need for camping? Well, how much power does a single solar panel produce? The answer is, it depends.You can use the chart below for a recommended kit and common battery requirement to get started. Or, if you'd prefer a more detailed explanation of solar output and tips on estimating your panel needs, read on below the chart.

RV Solar Kit Recommendations

Amp Hours Needed (Per Day)Solar Kit Rec. (DC)# 12V Batteries
27.42 aH 80W Eco Kit 2
53 aH 170W Overlander Kit *Most Popular2
Amp-Hours Needed (Per Week) Solar System Rec. (DC + AC) # 12V Batteries
"Solar Sizing Calculator." gpelectric. Accessed 3 Jan 2019.*Amp-hours are based on 6 hrs. usable sunlight per day.

Solar Panel Efficiency

Solar panels are rated for their max efficiency—that is, a 100-watt solar panel will produce 100 watts in perfect conditions. (And unless you're the luckiest camper in the world or have discovered a way to control the weather, we guarantee you won't always have perfect conditions.)The weather, temperature, time of day, and other factors influence the amount of power solar panels actually generate. There are multiple online calculators available that take your geographic location, the time of year, etc. into account and provide the average usable hours of sunlight you can expect.

Tips for Estimating RV Solar Panel Needs

Although actual output may vary based on the factors mentioned above, you can get yourself to a ballpark figure using a couple of tips. The general rule of thumb is that a 100-watt solar panel can produce about 30 amp-hours per day, so you can use this guideline to determine about how many panels you need. Another suggestion is to match your battery capacity in amp-hours with your solar output in watts. A 300 amp-hour camper battery, for instance, would need around 300 watts of solar power. Also keep in mind that solar panels experience a 75-90% drop in efficiency on cloudy days, so it's good to have slightly more than you need when it comes to solar power (about a 20% cushion, if possible, to account for less-than-ideal conditions).

Determining How Many Panels We Need (Examples)

We're going to jump back into the math one more time (it turns out everyone's eighth grade math teacher was right—we do need this stuff).In our example from the last section, we know that we use 50 amp-hours per day when camping in our RV. We want to keep our battery at optimal charge, so we're going to need a solar setup that can generate this same amount of power per day. If we look at Go Power's 100-Watt Retreat Solar Panel as an example, we can see that its power output is 5.43 amps per hour.If we assume 6 usable hours of sunlight per day, that's 32.58 amp-hours per day, which is pretty close to our ballpark figure of 30 amp-hours per day. From here, we can determine that two of these 100-watt panels would give us about 65.16 amp-hours a day, which covers our requirement of 50 amp-hours. Our two 100-watt solar panels equal 200 watts together, which also checks out with our guideline of matching our battery amp-hours with our solar panel wattage. We even have our 20% "cushion," though if we want to add a smaller panel for faster charging or to help pick up the slack on cloudy days, we can do that too.
RV Solar Panel Estimation Tips
How Many Solar Panels Does My RV Need - Infographic 1
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Related ArticlesRelated ProductsWritten by: Amber S. Updated on: 2/8/19

Questions and Comments about this Article

Rod S.

Can you comment on 12 v batteries vs 6 volt batteries. Im buying a new rv with 190 watts of solar built in and one 12 v battery. i can change to 2ea 6 volts now but is it worth the extra $250 to change?

Lee

Problem is, you can't just assume there are going to be 6 hours of daylight that the panels can use and they will generate 30Ah per day... The arc of the sun across the sky will shorten the direct sunlight hours.. So unless you want to rotate your panels to face the sun, you will get about 3 or 4 hours on the panels that equate their rated watts... It is also location dependent... Like someone in Alaska will need a lot bigger system than someone in Arizona... In the winter in Alabama you get about 3.5 peak hours of sun to generate the rated power... So in reality you may produce the 30Ah per day in a sunny state like Arizona if you turn the panels to follow the sun, but may only get 15Ah or 20Ah per day elsewhere...

Jon R.

I am looking for some assistance for setting up a solar panel system to power an off grid type cabin. It will be 12'x16' with a 70 Amp breaker box installed. How many panels would I need to provide enough power for lights, TV, a heater in the winter and a small refrigerator. Any assistance would be greatly appreciated

Etrailer Expert
Reply from Jon G.

You would need to do the math like what we mentioned earlier in the article. Find out all of the power usage each item will have and then make sure your solar panel system can provide what's necessary. If you can get me the amount of amp/hours you'll be using a day then we can choose from the list presented in the article according to that number.

Jon W.

I'm interested in boondocking, and your 130 watt, solar panels with digital solar controller. So this will automatically charge batteries and adjust when fully charged or do I have to manage or buy a separate piece of equipment to do this

Etrailer Expert
Reply from Jon G.

The 130W system and controller # 34282730 will auto adjust once the battery bank is full so that your battery bank will remain full but will also not become overcharged.

Robert W.

I've installed. Solar on 2 rvs. I have 200 Watts of solar 200 amps of batteries. We boondocked more than 200 days. I've done a lot of research. This was the best explanation of solar I've ever seen. Great job.

Etrailer Expert
Reply from Jon G.

Thank you for the kind words!



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