We earn commissions from purchases

Calculating The Perfect RV Solar System

To Cover All Your Needs And Wants Part Math – Part Balancing Act

So you’ve decided to join the boondocking life and get your RV some solar power. That’s an exciting plan, but it comes with a host of difficult decisions, many of which are dictated by reality rather than personal choice.

If you’re truly lucky, you won’t have an RV yet. Unfortunately, most folks don’t decide to try boondocking until they’ve fallen in love with the RV lifestyle and already own their rig. So, we will aim this article at those who wish to upgrade their RV to solar.

If you have yet to purchase your RV, this article will help you to better understand your needs when it’s time to buy.

Discovering Your Inclinations

While boondocking is easily defined as camping outside traditional campgrounds without access to power, water, or sewage hookups, there’s still a great deal of room for different takes on the trend.

For some, bringing all the perks of modern life with you is what makes boondocking fun, while others consider that cheating. You need to decide what boondocking means to you and what you need to make the experience as positive as possible.

Defining Your Limitations


The first step in designing a new RV solar power system is to figure out what you refuse to live without. If your RV looks like the one above, you’re going to need a large solar system.

But if you’re more of a cooking over an open flame and reading by candlelight type, your solar needs will be equally modest.

Figuring out what you simply must have is the first step to designing your solar system. Once you know your needs and have accepted your wants, it’s time to find out how much juice all that convenience will take to run.

Just The Facts

Figuring out your power needs is relatively straightforward. All appliances come with labels that list their power usage. All you need to do is gather that information for every appliance and then do a little math.

First, you need to understand that everything solar is measured in watt-hours(Wh). So, you need to find the watt rating of each appliance. Unfortunately, not every device has a watt rating. Some only have the amps calculated.

RV with solar panel

Luckily, taking amps to watts is easy.

If a one-piece computer and monitor is rated at 3.33 amps, you need to convert that number to watts. Wattage is simply amps multiplied by volts.

So, you take the standard household voltage of 120V and multiply it by 3.33 amps.

Or – 120 (volts) x 3.33 (amps) = 399.6 (watts)

So the Watt rating of your computer is 399.6

Now, the standard microwave in an RV is about 1000 watts.

But we can’t just add the wattage of each appliance because we want watt-hours(Wh), not watts.

To get the watt-hours of any appliance, you must multiply the watts by the amount of time it’s in use.

Now, let’s assume you only use your computer to communicate with work and check emails, which you can do in one and a half hours.

So, we take the watt rating of the computer (399.6) and multiply it by your usage based on hours (1.5) to get your watt-hours.


399.6 (watts) x 1.5 (hours) = 599.4Wh

Now, let’s say that you only use your microwave to heat your coffee in the morning and only use it for 3 minutes daily.

So, we take the microwave’s wattage (1000) times the 3 minutes of usage (0.05 hours) to get the watt-hours for your microwave.

RV with solar panel


1000 (watts) x 0.05 (hours) = 50Wh

Now that we know the watt-hours of each of your two appliances, we can simply add them up to determine your power usage.

So, we add the computer (199.8Wh) and the microwave (50Wh) to get a daily usage of 649.4Wh.


199.8Wh + 50Wh = 649.4Wh

Now, let’s further assume that you use no other appliances, so your daily power need is 649.4Wh.

You now have the number that will drive every other decision about your new RV solar system – 650Wh.

If you find math to be no fun, you can just place a power meter between your RV and your shore power and read what it says after a full day of using all your appliances. 

Power meters are a small investment but are also handy for quickly noting problems like shorts when you consistently monitor your daily power usage.

The Dirty Truth About Solar Panels

Solar panels are remarkable things, but they never live up to the promises on their labels.


Because those promises are based on perfect sunlight, perfect temperatures, and perfect solar systems.

rv at the forest

None of these things exist outside of testing labs.

In the real world, days are longer or shorter, sunlight is better or worse, and power systems have inefficiencies that cause power to be wasted.

So, you are best off assuming that the average 100-watt solar panel will give you 350Wh on any given day rather than the 1000Wh promised in the rating.

In this scenario, you need a minimum of 650Wh each day. So, two standard 100-watt solar panels should meet your needs.

You can increase or decrease the output of each solar panel depending on the type of panels Link to RV solar panels article you purchase, though the changes between each type are far from dramatic.

Don’t Forget The Batteries

When designing your new solar system, remember that you need a battery bank that can get you through a lengthy period of low light while still meeting your usual demands.

Solar batteries come in two types: lead-acid and lithium-ion. There are many arguments about which type is better for your needs, but they all come down to budget.

If you can afford to invest in lithium-ion batteries, do so. They charge faster, don’t drop in voltage as they discharge, can handle thousands of cycles, and weigh less than lead-acid batteries.

The appeal of lead-acid batteries is their cost, which is a fraction of lithium-ion batteries. Plus, if you can find serviceable lead-acid batteries, you can make them last virtually forever. But they are also extremely heavy and inefficient.

RV with solar panel

Whichever direction you decide to go, be sure to build a bank big enough to meet your needs for at least two days.

And Don’t Forget Reality

As you plot your RV’s new solar power system, keep in mind the unchangeable facts. 

  • You only have so much space on your roof.
  • You only have room for so many batteries.
  • Your project budget can only stretch a certain amount.
  • You can only put so much weight on your RV’s roof before it gets tippy.

You must try to balance these immutable facts as you design your dream solar system for your RV. You’ll find that the list of things you can live without will be forced to grow as you adjust for space, storage capacity, safety, and affordability.

But don’t let that get you down. Regardless of which system you decide to install, you’re still traveling farther in more comfort than anyone dreamed possible just a couple of decades ago.