Powering an RV Air Conditioner with Solar
"Can I run my RV air conditioner with solar?"
This is one of the most common questions we get asked. The short answer is: yes! In fact, many of our clients do just that.
With that said, there is no “one size fits all” when it comes to running an electrical load of this size with solar. Factors such as outside temperature, RV or camper van insulation rating, and AC efficiency can all impact how much power we need to do this.
In addition, the solar system must be appropriately sized to also power any other appliances we want to run, like a microwave, refrigerator, and TV.
The bottom line: running an AC with solar is no small task, but it is absolutely doable. Let’s get into it:
Balancing Goals and Budget
We always start by finding a balance between our goals and budget.
A renewable energy system large enough to power an air conditioner alongside your other appliances will require a substantial amount of solar, batteries, and other power electronics. For materials alone, you can expect to invest $10k+. Though it’s worth noting, most of the components in your system can last over 10 years!
That said, you have options. Some folks prefer to start with a smaller system designed to expand over time. Others appreciate our financing options for their system with Affirm.
TL;DR: Start with the RV Solar Energy Audit
Ok, so now you know it’s absolutely possible to run the AC in your RV with solar. We’re about to dive deeper into how we go about determining what size system is best for you, but if this is more information than you need, here’s your out!
Take a few minutes to fill out our RV Solar Energy Audit Calculator. Once you’re finished, select the checkbox next to Send me a free, personalized quote. From there, you’ll receive an itemized quote with all the components we’d recommend to meet your power needs.
Need a little more guidance? Check out our blog on How to complete an RV Solar energy audit.
We’ll be using this terminology throughout the blog to calculate how you can run an RV air conditioner off of solar. Take a minute to get familiar.
Wh or Watt Hours: How many watts a load will use per hour of operation.
For example, an AC is rated at 1500 watts. If the AC is used for 1 hour continuously, it will consume 1500 watt hours.
Ah or Amp Hours: This is usually used as a measure of battery bank capacity.
For example, a 400Ah battery bank is capable of supplying 400 amps for 1 hour, or 100 amps for 4 hours.
Ohms law states that V x A = W. There are many applications for this formula, but today we will use it to understand the relationship between battery capacity and power consumed.
For example, if we convert our 12.8V 400Ah battery bank to Wh (400Ah x 12.8V = 5,120Wh), we can more easily determine how many hours this battery bank can support an air conditioner: 5,120Wh/1500W = 3.4 hours
Scenario: Running an RV air conditioner off of solar
Before we can run our RV air conditioner with solar, we need to calculate how much solar will do it.
John wants to run the air conditioner, watch the news, make coffee, do dishes, and take a shower every day without plugging into power. So, John fills out the energy audit calculator with this info, selecting the appliances he wants to run and how long they’ll run each day.
Importantly, John has noticed that his air conditioner cycles on and off while in use. So even though he has it on for 8 hours each day, it only runs about 50% of the time. This means the actual run time is closer to 4 hours.
After filling out the energy audit calculator, John determines that his daily required energy is 8,485.95Wh (10% is added for power lost through conversion, also called inverter loss).
At this point, we can calculate how much solar will be needed to support John’s energy needs during peak sunlight hours. These are the hours per day when sunlight is high enough in the sky to allow for peak solar performance. Note that this varies depending on geographical location and weather, but the average for North America is 3-6 hours per day.
We find that, with 5 hours of peak sunlight, John would need about 1700 watts of solar. But there’s one more factor we need to consider.
We also need to a buffer of 25% when doing our solar calculations. This is because solar panels are tested (and rated) at a cell temperature of 25 degrees Celsius, or 77 degrees Fahrenheit. In the real world, with ambient temperatures of 77 degrees Fahrenheit, solar panels cells are typically 30 degrees hotter than the ambient temperature.
As electronics heat up, they derate, or produce less than what they’re rated for. On average (depending on ambient temperature and solar irradiance), you can expect a solar array to produce about 75% of its rated output, so a 1600 watt array will actually produce 1200 watts during peak sunlight conditions.
With this in mind, we add 25% to arrive at our actual solar requirement:
Depending on the size of your RV, you might be thinking, “There’s no way I will fit 2000+ watts of solar on my roof.” You’d be surprised – see our note on Maximizing Solar Potential.
John now knows that he will need 2,121.48w of solar to power his RV air conditioner and other appliances. If John only wanted to power his RV appliances during peak sunlight hours, we could stop here.
Realistically, John will need a system that can perform in the morning and evening during lower light conditions. It will also need to work on cloudy days and at night, when there is no solar production. Solar panels alone are not enough: we need a battery bank, solar charge controller, and inverter in order to be truly independent from shore power or generator use.
Since John completed the energy audit and understands his expected energy use per day (8,485.95 Wh/day), he can easily determine an appropriate battery bank to support his needs.
Before we calculate optimal battery capacity, we should consider what voltage we want our battery bank to be. Air conditioners draw a substantial amount of power, and because of this, we usually recommend a 24V or 48V battery bank (primarily to improve system efficiency).
While it’s true that most RV’s have 12V loads like LEDs, vent fans and water pumps, these are easily accounted for with the addition of a DC-DC converter. This will take the higher voltage from our battery bank and step it down to 12V for these loads.
After all, our 120V appliances will draw significantly more energy relative to our 12V loads. This means that instead of starting from 12V, it’s more efficient for an inverter to bring 24V or 48V up to 120V.
For this example, let’s consider a 24V system for John. We’ll take his expected 8485.95Wh over 24V to get 353.58Ah. From there, we add 10%, since we don’t want to fully discharge our batteries to zero. 353.58 + 10% (or multiplied by 1.1) = 388.9Ah at 24V.
So John needs a 24V lithium battery bank with at least 388.9Ah of capacity. Knowing this, John has decided to use (2) of the Victron Energy 25.6V 200Ah Smart Lithium Batteries in order to achieve his goal of one full day of autonomy (plus a little extra). Two of these batteries will give John a total of 400Ah of storage at 25.6V, or 10,240Wh of storage. (Psst… remember Ohm’s law? This is equivalent to 800Ah at 12V)
Let’s check our work: John needs 2,121.48W of solar to support his expected energy usage (8,485.95Wh/day). If we multiply this by 5 hours of peak sunlight, we can expect 10.6kWh of solar produced each sunny day.
This should keep John’s 10.24 kWh battery bank properly charged. He can now use this energy storage to support his needs during low (or no) sunlight conditions.
Quick recap: John completed an energy audit and determined his expected energy usage to be 8,485.95Wh/day. From there, he calculated his optimal solar array to be 10.6kWh. To sufficiently store this DC energy, his battery bank will be 400Ah at 25.6V (10.24kWh).
Now we need to take this DC energy and turn it into AC energy to power our 120V appliances. And wouldn’t it be cool if we could do the reverse, turning AC energy from shore power or a generator into DC energy that charges our batteries?
Enter: The inverter/charger.
John has read our blog, What Size Inverter Do I Need For My RV or Van Conversion. From there, he used the Inverter Size Calculator to determine which size inverter he’ll need. He’s settled on the Victron Quattro 5000VA 24-Volt/120-Volt Pure Sine Wave Inverter 120 amp Battery Charger 100/100.
Now that he has selected an inverter, we need to verify the batteries are capable of discharging enough current (amperage) to operate the inverter and loads. Using the inverter calculator, John determined that his simultaneous load draw at a given time could be upwards of 3200 watts.
Let’s go back to our reliable friend Ohms law: 3200 W / 25.6V = 125 amps.
Referencing his batteries’ datasheet, we see that each 25.6V 200Ah Smart Lithium battery can safely discharge 200A. With two in parallel, we double this value to 400A continuous discharge, which will easily handle our power output requirements.
At this point, John has a solid plan with an inverter powerful enough to support his 120V loads, a battery bank large enough to support his expected energy usage, and a solar array sized to keep his battery bank charged.
We’ve covered a lot in this post, and if you’ve made it this far, kudos! We’ve got just a few more things to share before we wrap up.
Note on the Micro-Air EasyStart:
The Micro-Air EasyStart is a must have on any off grid capable system. It does an incredible job of lowering the required power to start the air conditioning unit, which will relieve strain on the entire system. Less strain means higher efficiency and increased lifespan for your inverter, battery bank, and even the AC!
Note on Maximizing Solar Potential:
You may have determined that it’s not feasible to fit enough solar on your roof to cover your energy needs. If this is the case, you have options.
For one, you can add 400W-600W of solar using a few deployable (folding) panels on the ground in combination with your permanent roof-mounted panels.
Another option is a custom solar rack that elevates the solar panels above any obstacles on your roof. This usually only adds about 2” to your vehicle or trailer’s overall height. As a DIYer, this will require quite a bit of extra work. If you’re looking for a professional installation, we’d be happy to help with a custom solar rack.
Note on Generators:
A backup generator is always a good idea to supplement your solar system. It can assist the inverter and battery bank when running the air conditioner, ultimately helping reduce the amount of batteries required in the system. It can also be used to recharge the battery bank in times of low solar, or to support extended times away from shore power.
So, is it possible to run an AC in your RV, van conversion or tiny home with solar?
A resounding yes, with the understanding that this is an investment that requires a large enough solar array, battery bank, and inverter system.
If you are living in your RV full-time , prefer to escape crowded RV parks during vacation, or just get tired of hearing the generator drone on, a renewable energy system for your RV can be a great solution.
At the end of the day, your goals and priorities will determine what makes sense for you.
If you’d like a free quote for a renewable energy system designed to meet your specific needs, take a few moments to fill out our energy audit calculator.
Do you have dreams of your own RV solar system? Do you currently have a system capable of running your AC? Share your questions, comments and experiences with us and the rest of the community below!