RV Air conditioners require an absurd amount of energy to keep them running all the time, which makes it expensive to run them solely on solar and battery power. However, you can still reduce the costs by taking a different approach.
Compared to traditional built-in HVAC systems, mini-splits are pretty energy-efficient. They use less power (kW) and consume less energy (kWh), and in general, they cost much less to run off solar.
In this article, I’ll walk you through the power usage of mini-split air conditioners, as well as their energy consumption, and I’ll explain their advantages over built-in RV air conditioners.
How many watts does a mini split use?
Like other types of air conditioners, the electrical power that a mini-split ac uses depends mainly on its size (BTU rating).
In general, mini-split air conditioners used in RV installation are usually rated at 12000 BTUs, a mini split of this size uses up to 900 Watts of power to achieve the set temperature, and uses around 300 watts to maintain it.
The following table provides the electrical specs for different BTU ratings:
|BTU Rating||Avg. Running Wattage||Wattage at Set Temperature||Starting wattage||Avg. Amperage at 115-130 V(AC)|
|9000||700 Watts||100 – 200 Watts||2000 – 2500 W||6 Amps|
|12000||900 Watts||200 – 300 Watts||3000 – 3500 W||8 Amps|
|15000||1100 Watts||300 – 400 Watts||3500 – 4500 W||10 Amps|
|18000||1400 Watts||350 – 500 Watts||4500 – 5500 W||12 Amps|
|24000||1800 Watts||600 – 800 Watts||6000 – 7500 W||16 Amps|
Related: How much power does an RV AC use?
Note that the Average Running Wattage provided in the table represents the power that the air conditioner uses to reach the set temperature. Wattage at Set temperature estimates the amount of power used to maintain the temperature setpoint.
Furthermore, please note that these are rough estimates of the electrical power usage. When trying to figure out things like battery size, or solar power requirements to run your mini-split, you’ll need to have an estimate of its electrical energy consumption.
This brings us to the next section.
How much energy does a mini split use?
Generally, and like any type of air conditioner, the energy consumption of a mini split depends on factors such as:
- The difference between the outdoor temperature and the set temperature
- The amount of space
- How well this space is insulated
However, it is still possible to give rough estimates based on the AC’s BTU rating.
As a rule of thumb, a mini-split air conditioner rated at 12000 BTUs, would consume between 15 and 20 kWh of energy per day on days where the temperature is around 95°F. On a moderately warm day (80-85°F), the same AC would consume around 10 kWh of energy over 24 hours.
Assuming the set temperature is around 70°F and that the air conditioners are properly sized, the following table provides some rough estimates of the energy consumption of different sizes of mini splits, at different outdoor temperatures:
|Outdoor Temperature||BTU Rating||Estimated Daily Energy Consumption (kWh/day)||Estimated Hourly Energy Consumption (kWh/hour)||Estimated Daily Energy Consumption (Ah/day) at 12V||Estimated Hourly Energy Consumption (Ah/hour) at 12V|
|85°F||9000||8 kWh/day||0.35 kWh/hour||650 Ah/day||27 Ah/hour|
|12000||10 kWh/day||0.4 kWh/hour||850 Ah/day||35 Ah/hour|
|15000||12 kWh/day||0.5 kWh/hour||1000 Ah/day||42 Ah/hour|
|18000||14 kWh/day||0.6 kWh/hour||1200 Ah/day||50 Ah/hour|
|24000||18 kWh/day||0.75 kWh/hour||1500 Ah/day||63 Ah/hour|
|95°F||9000||12 kWh/day||0.5 kWh/hour||1000 Ah/day||42 Ah/hour|
|12000||15 kWh/day||0.6 kWh/hour||1250 Ah/day||52 Ah/hour|
|15000||20 kWh/day||0.85 kWh/hour||1650 Ah/day||70 Ah/hour|
|18000||25 kWh/day||1 kWh/hour||2000 Ah/day||85 Ah/hour|
|24000||35 kWh/day||1.5 kWh/hour||3000 Ah/day||125 Ah/hour|
|100°F or more||9000||15 kWh+/day||0.6 kWh+/hour||1250 Ah+/day||52 Ah/hour|
|12000||20 kWh+/day||0.85 kWh+/hour||1650 Ah+/day||70 Ah/hour|
|15000||24 kWh+/day||1 kWh+/hour||2000 Ah+/day||85 Ah/hour|
|18000||30 kWh+/day||1.25 kWh+/hour||2500 Ah+/day||105 Ah/hour|
|24000||40 kWh+/day||1.7 kWh+/hour||3300 Ah+/day||140 Ah/hour|
Please note that the values in this table are rough estimates, and their purpose is to give you an idea about the energy consumption of these air conditioners. The next section explains how you can get more accurate values.
How to measure an air conditioner’s energy consumption accurately?
The best way to have an accurate idea about the energy consumption of your AC is to use an electricity monitor.
Devices such as the Kill-A-Watt meter, allow you to monitor power usage and can calculate the energy consumption over a certain period.
The following video explains what this metering device is and how you can use it:
Mini split vs RV rooftop air conditioner: Which is better for solar?
One of the main differences between mini splits and RV rooftop air conditioners is that mini-splits use VSD technology, which stands for Variable Speed Drive. This technology allows mini split air conditioners to consume less energy while ensuring a comfortable and more stable temperature inside your RV.
While built-in RV air conditioners turn ON and OFF to reach and maintain the set temperature, the inverter-driven compressor of a mini-split allows it to adjust motor speed relative to the temperature.
For example, a 15000 BTU RV air conditioner runs at a fixed wattage of about 1500 Watts and completely turns off as soon as it reaches the set temperature. Only to turn back on in a few minutes once the indoor temperature rises.
This results in poor control and repetitive spikes in power and current usage. Which in the long run, can damage both the compressor and the DC/AC inverter.
A 15000 BTU mini-split air conditioner will slowly ramp up its wattage until it reaches about 1100 Watts. Once the set temperature is achieved, the air conditioner will run at about 300 Watts and will maintain the set temperature in a stable manner.
Thanks to this feature, mini splits are able to consume less energy while performing better.
Another key difference is that mini-splits are ductless, which means the cool (or warm) air is directly delivered to the room, eliminating a good portion of energy consumption.
In fact, according to EnergyStar, the absence of ductwork and the VSD technology in mini split air conditioners, make them 30% more energy-efficient. In other words, on average, mini splits consume 30% less energy than traditional HVAC systems.
This amount of energy might not seem much, but if you’re buying solar equipment (especially batteries), this can save you thousands of dollars.
Another good thing about replacing your built-in AC with a mini-split is that you can free up more space to fit more solar panels, which will raise your chances of making your RV 100% solar powered.