In all the time that you spend on the road in your motor home, the sun shining over your head, the wind blowing in your face, the thought must have definitely popped up in your mind on more than one occasion.
‘Can you run those dang rooftop ACs on solar energy?’
Sounds like it’s just the way that it was meant to be.
The AC perfectly positioned on the roof to soak in all that the sun has to offer.
No recurrent costs for electricity at camping grounds or costly fossil fuel to power the generator.
Off-the-grid living at its best.
We have been asked that question by newbie RV enthusiasts a million times.
What makes this question even more relevant now is that solar technology has improved by leaps and bounds in the past few years.
A decade ago, people would have just scoffed at you for your wishful thinking. You could have powered a few bulbs maybe.
But now, with larger inverters, better batteries, and more efficient solar panels, one can’t help but think that it might just be possible.
Today, we give you the answers that you were always looking for.
We will talk about using solar energy to power the most power-hungry appliances in your RV. The costs, the challenges, the pros, and the cons.
For those looking for a quick answer as to whether solar panels can power an RV air conditioner, the answer is yes. However, there are a number of factors that influence the answer including the number of panels, cost, efficiency, appliances as well as other conditions. Read on if you’d like to find out more.
Can Solar Panels Power an RV Air Conditioner?
How a solar panel works
In theory, solar panels sound like the simplest of devices.
Put them out in the sun, they capture the sun’s energy and convert it into electricity.
But the entire process of converting sunlight into usable energy that can power up appliances in your RV is a lot more complex.
- The sun is a massive nuclear reactor that is releasing photons, which are essentially tiny packets of energy. In about 8.5 seconds, these photons reach the earth. And as unbelievable as it sounds, in just one hour, we get enough solar energy that can power our entire planet for one year. Now think of the positives of harnessing that energy endlessly. We would no longer burn toxic fossil fuel. The environment would be a lot cleaner. And we would have an endless supply of energy for eternity. That’s the theory. Let’s talk about the challenges.
- A solar panel contains an array of photovoltaic cells that capture these photons and knock the electrons loose. These electrons then travel from the positive to the negative end of a battery completing the circuit and generating electricity. However, a solar panel creates DC energy which then has to be sent to an inverter to be converted into AC energy to power your appliances.
So, there you have the key components to complete a solar grid. The array of solar panels, the battery to store the electricity and an inverter to convert it into DC.
There are other components too. But these are the most important ones that you cannot do without.
How many solar panels do you need to install?
The big question, is how many solar panels do you need to power the rooftop AC?
Unfortunately, there’s no definite answer to this as there are a lot of variables, some of them unpredictable, that can affect the output of a solar panel.
But we can always get a ballpark figure and use that as a reference to work with.
A solar panel designer will do an energy audit for your RV. But you can do it yourself. It’s a fairly simple calculation.
Check the average draw of all the electrical appliances in the RV and multiply it with the number of hours that each one will be run in a day. This gives you the total amp hours consumed.
For example, to power a 13.5K rooftop air conditioner for 5 hours a day, you need at least 700 amperes per hour (ah) from the battery. That’s provided that no other appliance would be running simultaneously.
To generate 700 ah, a solar panel would need to generate approximately 110 amperes per hour for 7 hours per day.
This can work on a bright and sunny day. On a cloudy day though, the chances of such a high output every hour are slim, which means that a lot more would be needed.
That’s approximately 1500W or a 1.5KW solar panel that we are talking about.
As of January 2019, the approximate cost for a solar panel in the United States is $3.05 per watt. That means that one single 1500W panel would cost you $4575.
After deducting the 30% Federal ITC discount, provided that there is no other state incentive or rebate, the cost comes to around $3202.
That’s just the cost of the solar panel array mind you, to run one AC for 5 hours every day.
The Battery Bank
Considering that one AC draws around 150 amps, you need at least 150 ah to power the rest of the appliances on cloudy days or during the night.
This means that you need a large battery bank that has the capacity to store the amount of electricity generated by the panel.
Battery capacity is determined by kilowatt-hours (kWh). The good part is that you can stack multiple batteries to increase the storage capacity of a bank.
However, it’s not limited to the storage capacity alone. You also need to consider the power rating, which is the amount of electricity that the battery can actually provide to the appliances at one time. This is determined in kilowatts (kW).
A battery with a high storage capacity but a very low kW rating can provide the bare minimum electricity needed for small appliances for a long time period, like an entire day.
Or, one with low capacity but a high kW rating can power all the appliances in the RV for just a few hours.
Then there’s the Depth of discharge (DoD) to consider. This stands for the maximum amount of power in a battery that you can draw before you must recharge it again.
So, if you have a 20kW battery with a 90% DoD, you can only draw a maximum of 18kW. Even that would be maxing it out.
Ideally, you should have a battery bank that’s double the capacity of the electricity that you draw each day. This allows you to store enough electricity to last through the night and on cloudy days.
The Inverter
The inverter is what converts the DC energy produced by the solar panel into AC energy.
Traditionally, the solar industry used string or central inverters which would power all the appliances in a home or in an RV.
You had one single box to deal with. It was cheaper. Maintenance was as easy as flipping a switch and the grid would shut off.
But string inverters aren’t the most efficient devices. It automatically tries to optimize for the weakest solar panel in the array, which drags the performance of the other panels down.
That’s why the industry is fast transitioning into micro-inverters which are tiny inverters positioned under each solar panel.
This allows the user to derive the maximum potential of each and every solar panel.
So, assuming that you will install one micro-inverter only for the air conditioner, you will need at least 3.5 – 4K W inverter for the AC alone, as you can never max the inverter out. You need to have some leeway.
You can install a soft start as a workaround and opt for a smaller inverter. But if you are going solar full time, we highly recommend a larger inverter rather than cutting corners.
The finances
Those numbers are just approximated, mind you.
But we’ve made a list of some the appliances that one can expect to find in an RV.
And we calculated the total consumption for running 1 x 10000 BTU air conditioner for 8 hours, 5 x 60 watt LED bulbs for 10 hours, 1 20 CU refrigerator for 24 hours, 1 LCD TV for 10 hours and 1 Laptop for 5 hours per day, assuming that you get at least 5.5 hours of sun each day.
You need 533 Kwh/mo to power those. That’s 14 solar panels of about 300 W each.
Based on the above pricing, the cost would be $12078.
Add to that the cost of installation, battery, cables, soft start, and a battery monitor and you are suddenly looking at a staggering amount of money.
What if you have two or three air conditioners in the RV?
Is it worth the cost?
Before you jump on to the Solar bandwagon and commit to making a huge investment, there are a few questions that you need to ask yourself.
The answers will allow you to make a more informed decision.
Q, What’s your primary motivation to switch to solar energy?
A. Is it saving money that you pay for utility at camping sites? If yes, then do you camp for more than 5-6 days at a time at places that don’t have campsites with electrical hookups? Most part-time campers don’t. They usually take their RVs out for a spin on weekends or stick to regular campsites. And if that’s the case, then you can very well survive on a fully charged battery for two to three nights.
But if you do go dry camping for 5-6 days at a time or, if you are a full-time RVer, then you can consider switching to solar energy or at least try powering some of the appliances with solar panels. Saving even $40 a night that you would otherwise pay at campsites can save you $1200 a month. You can easily recoup the upfront costs with the savings that you make over a year.
Are you switching to solar just because everybody else seems to be doing it? A lot of people have made this rookie mistake only to regret their decision later. We highly recommend that you do your research and consider all the pros and cons before you jump into it.
Do you wish to reduce your carbon footprint? Well, as ‘green’ as it sounds, there will be very little difference to the carbon footprint by switching a few appliances to solar energy. But if you are committed to living off the grid, at least do your research and read up on the details.
Q. Will you mainly be traveling in areas with ample sunlight?
A. Solar panels are weather dependent. It will only be able to produce sufficient electricity to power all the appliances in a large RV if there are five to six hours of direct sunlight each day. That’s the bare minimum mind you. Will you be traveling only in areas that have five to six hours of direct sun? If not, then always carry a backup source of electricity, like a generator with you. The last thing you need is to be caught without power while you are miles away from civilization.
Q. Do you have the roof space needed to install the panels? Is there sufficient room to store the battery bank?
Rooftop space is usually unused. And a solar panel is a great way to put it to use. But most RVs don’t have the room needed for panels and battery storage to run power guzzling appliances all day.
Also, anything else up there might be an obstruction. Like antennas or the very rooftop AC that you are trying to power, or vents. Flexible panels (pricier) can help you work around the obstructions. Check if you have sufficient room in the storage bays for the battery bank. It will be permanent fixtures, mind you.
The other option is to use a solar suitcase, a portable solar panel with a charge controller. That will be more expensive but will save on roof space.
Q. Are you willing to switch a part of your energy consumption to solar?
A lot of users these days install panels to power a part of their RV lifestyles with solar energy. If you have three ACs for example, power one with solar energy and connect the other two to the generator or shore power. Not only does this tick all the above-mentioned boxes, but it also reduces the initial investment by more than half. This can also lengthen the time that you can last on batteries while camping.
Q. Are you willing to give up on a comfort or two?
Many a time, you cannot afford the system that you need to completely go off the grid. You may not have the room needed for the panels or it would be plain unaffordable. This would mean giving up on the idea entirely or sacrificing a few comforts that you might be used to.
For example, if you can avoid using a microwave or a hairdryer, both of which are power-hungry appliances, then you can still manage to create a solar grid that can very well power your AC for a few hours each day. Can you run the AC only on the hottest days and not every night? Can you install a ceiling fan that can be used in synergy with the AC to improve its efficiency and to reduce its runtime?
The pros and cons of going solar
All said and done, here are some of the pros and cons of switching to solar panels to power your RV.
Pros
• Clean, renewable source of energy
• Environment-friendly
• Unlimited access to electricity even in case of a natural disaster (Provided you live in an area with ample sunny hours each day)
• Very little maintenance cost if any
• You can explore areas that aren’t covered by the grid as long as it’s legal to camp there
• Perfect for boondocking
• Save money by dry camping. Avoid paying the rent for the campsite as well as for electricity
Cons
• Huge upfront costs depending on how much energy you are looking to generate
• Will work only in areas with good direct sunlight
• Can be a challenge on cloudy days
• May not
Closing thoughts
That’s it.
That sums up our brief guide on powering your RV air conditioner using solar panels. We hope that this suffices as a starting point for your research.
If you have anything to add to this or if you feel that we’ve missed out on anything, do give us a holler in the comments box. We’d love to hear from you.
If you liked this article you might want to take a look at our other RV how-to guides here or our other RV articles here.
