The beauty of hoping in your RV and enjoying a new lifestyle with the freedom to travel anywhere is that you don’t have to sacrifice modern amenities.
Technology and innovation have paved the way for more people to embrace the nomadic world while also getting to relax in a personalized motorized home.
One of the best ways to get out and see the world is by adding solar panels to the roof of your RV. This empowers your travel by reducing the number of electrical hookups you have to find while parking.
A set of panels can power everything you need, from a TV to binge the latest season of whatever you’d like to the coffee pot on your counter for a morning cup of Joe.
How much solar power you will need for your RV depends on a few factors:
- What will you be powering?
- What is your budget?
- How often will you be off the grid?
A rule of thumb is that the average RV uses 120 amp hours of solar power, whereas a Class A bumps it up anywhere from 240 to 360 amp hours.
But that’s really a shallow answer so let’s take a deeper look at how much solar power you need for your specific RV.
How do solar panels actually work?
Solar panels are a technology that uses light-absorbing cells to create electricity. The way it works is that you place solar panels on your RV’s roof and then run DC (direct current) into your single or set of batteries.
This charges the batteries and then sends the energy to your onboard inverter that changes the current into AC (alternating current), which we use in most of our appliances, technology, and daily needs.
Here’s a YouTube video explaining the process in depth:
How much solar power do you need?
There are really two ways to find out how much solar power you need.
The hard way
To figure out how much solar power you’ll need, you have to consider the total wattage you’ll be using daily.
That entails walking around your RV and writing down the wattage requirements on the side of your microwave, space heater, laptop charger, and anything else that you plug into an outlet.
Combine all those numbers together, and this gives you the amount of wattage you need per day based on your current use time.
The downside of using this method is the amount of math it requires 🙂
The easy way
The easier and my preferred way is to run a dry camping test.
Go off for the weekend and find a parking spot with an electric hookup. This could even be your driveway. Don’t actually plugin. Just go somewhere where you can get to the power when you need it.
Spend the next couple of days living a normal RV lifestyle. Don’t try to conserve extra power. Live like you would want while parked anywhere else in the world.
The secret sauce to this test is to pick up a battery meter that you hook up to your stack to monitor how much energy you’re outputting.
If, at the end of the two days, you have used 120 amp-hours, then you know you need roughly 60 amp-hours per day. So now you have an estimate for what your solar panel output will need to be moving forward.
As a side note, be sure you don’t dip below 50% power on any of your batteries. This can shorten the total lifespan of the battery, and you’re just doing a test.
Our figure is probably on the low end. Let’s bump it up to 70 amp-hours in a day. Say you were active for 17 hours and do some math.
70 amp-hours / 17 hours use = 4.12 amps per hour
Next, we will convert to a 24 hour day.
4.12Ah per hour X 24 hours = 98.88Ah per day
This is a decent estimate of our electric needs per day.
You also have to factor in what season you’re in and the amount of sunlight you’ll get. On average, you can expect 5-6 total hours of optimal sun exposure in the spring and summer.
That number goes up if you’re parked in Arizona compared to North Vermont.
What gear do you need for solar panels?
Now that you have your necessary Ah (amp hours) number per day, it is time to select your gear. You are going to need batteries! 🙂
I highly recommend the more expensive Lithium-ion battery because you can discharge up to 100% of the stored energy rating without causing any damage.
They are on the higher end, which is why most people go with the lead-acid type.
I’ve written a post on whether you should upgrade to lithium batteries. Give it a read.
You will also need a power inverter to convert DC into AC for your household appliances. Really do your research here. The more efficient your inverter is, the better your energy use will be in the long run.
Pick up a battery monitoring system like the one you used in your test that will give you a quick display of the percentage used from your battery and the number of amp-hours remaining.
Finally, you need a solar charge controller. This prevents the charge from going backward from your batteries to the panel and destroying their cells.
Time for the big reveal
We’ve got our gear and our number. We’re going to round up to 100Ah needed per day. The general rule of thumb is that a single 100-watt solar panel produces 30Ah per day. For our example, we can do some more lovely math and figure:
100Ah needed / 30Ah per panel = 3.34 panels
We’re going to round up, and that leaves us with 4 – 100 watt panels needed to operate our current lifestyle on the road.
We need to figure out how many batteries as well. This is going to vary depending on the amount of Ah the battery you select can produce. Remember, if you’re using lead-acid, you cannot go below 50%. The general formula is:
Total Amps needed / battery amp allowance = number of batteries
If we want to use a standard lead-acid battery at 12 volts that produce 70-85 amp hours, we can calculate the need:
100Ah needed per day / 70Ah produced = 1.42 batteries (round up to 2 batteries)
Remember that we cannot go below 50%, so we can take that original 1.42 batteries and double it to 2.84, or 3 total lead-acid batteries.
For our example, we need 4 solar panels and 3 batteries to use our RV on a typical day.
There are a few other things you need to keep in mind. Try to always get as much charge time as possible, so your battery packs can get all the sunlight they need. You’re going to want to make sure your RV can handle the weight and size of your panels safely as well.
You might also consider upgrading your lithium RV batteries. I’ve written an article discussing whether you should upgrade or not.
Do everything you can to make your power usage more efficient. For example, use LED lights everywhere and have let natural light move through your RV in such a way as to cut down on needing electricity.
At the end of the day, it comes down to personal usage and lifestyle. The more you can conserve energy, the longer life you’ll get out of your battery charge.
One last tip that often goes overlooked when I first asked myself how much solar power do I need for my RV was to keep my panels clean. Any dust or snow build-up reduces the ability of the cells to absorb light energy. Take a towel and go up on your roof to wipe them down every few days to make sure you’re running at full efficiently.
Good luck and happy charging! Life on the road is a lot easier when you have a solar panel array to keep your RV happy, healthy, and running at total capacity for your personal needs.