RV Solar Calculator + Essential Guide to RV Solar Power
One common question I get asked around the bonfire and on Facebook groups is “How much solar power do I need for my RV?”
Everyone’s RV power needs are unique. My goal of this post is to teach you the basics of how RV solar power works.
In this post I’ll help you:
calculate your power needs using a RV solar calculator
estimate how many solar panels you need
how many batteries you will need to power your RV
decide an an inverter size
I was in your shoes when we were budgeting to start traveling full time in our RV. I had very minimal electrical knowledge and experience outside of changing a ceiling fan. Fortunately, the internet is an amazing place.
Image courtesy of @thisairstreamlife on IG
After hundreds of hours of research, I built up enough confidence to install our RV solar system on my own. Completing this project felt like a lifetime achievement.
Through this RV solar series, I want to help you do something that you didn’t know that you were capable of accomplishing.
How Solar Power Works
While there are unlimited ways to customize your solar setup to fit your needs, every system has 3 major parts:
Solar Panels - Take in raw power from the sun
Charge Controller - Converts the raw power from the panels into a format that can easily be stored
Batteries - Store power to use when the sun is not out
Having these components will allow you to use DC power. Most RVs are configured to use DC power for your lights, water pump, slides, fridge, and furnace. Many newer rigs also have USB ports using DC power to charge small electronics like cell phones.
If you want to use AC power (think normal household plugs), you will need to add an inverter to your system. Inverters take the DC power stored in your batteries and change it to AC power that you can use for your TV and microwave.
Inverters can be pretty pricey ($200 - $2,000+) depending on which appliances you want to run, so many RVers choose to keep their systems simple and rely on DC power.
For example, we love our espresso machine and air fryer, and use them every day so we decided to invest in a high-powered 3000 watt inverter that cost us $1100.
I will discuss the system components in more detail in our post on RV Solar System Costs, where I will give our options on different solar kits as well as our exact RV solar setup.
If your head is spinning a little bit from all of this information, I recommend that you check out this video outlining a simple RV solar setup. Jared from All About RVs is an incredible source for various RV projects and gadgets.
RV Solar Calculator
Estimating your power use will take a little bit of research and math. To make things easy on you (and to take the math part off your hands), I built this RV solar power calculator for you to use.
Our estimated daily power use.
Start by listing out the appliances you will use on the road and how long you expect to use each of them.
I populated the spreadsheet with our average appliance use for reference.
Once you have this list, you will need to research watt usage of each appliance. Most appliances have the max watts listed on a sticker on the bottom or back. If you cannot find the sticker, you can look up the appliance online.
After you put this information into the calculator, it will estimate the sizes of the solar panel array (in watts) and the battery bank (in amp hours) that you will need to support your off-grid power use.
Our actual power use by day (1 kWh = 1,000 watt hours)
While the calculator is a simple estimate, we found that our estimate is very close to our actual daily use.
I included a screenshot from our charge controller app that shows how much power we have used over the last 4 days.
We tend to hover right around 2 kWh (2,000 watt hours) per day for two adults.
How Many Solar Panels Needed
When scoping out your RV solar setup, the logical place to start is with the panels. The capacity of a solar panel is measured in watts, with the advertised number of watts being the amount of power you can pull in during perfect conditions.
Because perfect conditions rarely exist, you should expect to max out at 80-90% of the advertised watts on sunny, summer days (it will be even lower in the winter).
I’ve created an RV Solar Calculator Tool to make things easier for you. The RV solar calculator will tell you how many watts of solar panels you will need and how many batteries you will need based on your estimated electrical use.
Again, most appliances have the max watts listed on a sticker on the bottom or back or you can use trusty google.
Once you have listed out your appliances, its wattage, and your daily use you can see how many watts of solar panels you will need.
For example, we estimated we will use a total of 1,705 watts/day based on our daily appliance use.
This calculation resulted in us needing just over 400 watts of solar panels.
Before you decide on the number and size of panels that you want, you should take measurements of the space where you will be mounting or storing the panels.
Your available roof space (or storage space if you choose not to mount your panels) will vary significantly depending on your rig. Our 30 foot fifth-wheel had plenty of space on top, so we chose to mount our 4 panels to the roof.
Once you determine the size and number of panels that you need, it is time for you to start shopping for the best RV Solar Panels.
You can currently find quality panels for under $1/watt. The price per watt has dropped by ~70% over the last 10 years, resulting in the panels being one of the least expensive parts of many RV solar setups.
Once you’re ready to mount your solar panels, make sure to read our guide on How to Mount and Wire Solar Panels to Your RV roof.
How Many Batteries You Need for RV Solar
While the number of solar panels is an important factor in your off-grid capabilities, it is not as important as the batteries you choose for your solar setup.
The solar panels allow you to pull in power on sunny days, but the true test of you solar setup is how well it operates when the sun is not out. This is where the batteries come into play.
Our battery bank. We have 4 Battle Born lithium batteries.
Choosing the right batteries is one of the most important steps to building your solar setup. Not only are the batteries the heaviest component of the solar setup, they are often times the most expensive.
With weight and cost being two huge concerns for any RVer, you will want to understand your options before you decide on your batteries.
There are two main types of RV batteries: lithium and lead acid. The major benefit to the more expensive lithium batteries is that you can use 100% of the listed storage capacity without damaging them.
If you discharge more than 50% of a lead acid battery’s capacity more than a few times, the lifespan of the battery will decrease dramatically. Because of that, you should double the battery bank size from the RV solar calculator if you choose to use lead acid batteries.
Check out this list of our Top 5 RV Batteries for RV solar setups.
Calculate the Inverter Size Needed
If you have decided that you will want to use AC appliances (anything that plugs into a normal wall outlet), you will need an inverter.
Inverters take the DC power stored in your batteries and convert it into AC power that wall outlets use. The capacity of an inverter is shown in watts. This capacity is the limit to how many watts can be used at one time.
For instance, we have a 3000 watt inverter. This powerful inverter allows us to use large appliances like our microwave (1500 watts), but it will trip the circuit if we use multiple large appliances totaling over 3000 watts.
You will want an inverter with a rating at least 500 watts higher than your most powerful appliance. That way, you won’t have to run around and unplug phones before you turn on the microwave.
If you would like to run multiple large appliances at once, you will need a very powerful (and expensive) inverter.
How Much Will My RV Solar Setup Cost —
After scoping out your solar system, you will need to determine what your total budget is for the project.
It is possible to build a quality RV solar system for anywhere from $500 to over $10,000, depending on the system components that you buy.
Continue reading How Much Solar RV Solar Costs, to learn different RV solar setup options, details on the system components and the best products to buy at each price point.
Please share this blog post!
