This article was written by our sister company, Upfitters Wholesale. 

 

What is the main reason for choosing a DC-Powered air conditioning unit?

Efficiency, right?

The premium price tag of a DC Powered unit is supposed to be balanced by a substantial increase in efficiency when comparing to an AC Powered unit.

However, sometimes marketing campaigns are full of smoke and mirrors! Read on.

Firstly, let's discuss a common misconception that traditional shore-power air conditioners are either incapable of running off of batteries or too inefficient to justify it. While this holds true for some units, the shore-power unit discussed in this article, GREE Eco-Cool 15k BTU Air Conditioner + Heat Pump, challenges this notion.

As a precursor to the product introduction itself, let's discuss the brains behind it. GREE is the largest air conditioner manufacturer in the world with over 90,000 employees and 22,000 patents. Their products are trusted by more than 300 million users across the globe.

You might ask, "Why does company size matter?"

With their large size, GREE is vertically integrated, which means that they produce every component in-house that goes into their products, as opposed to sourcing components from various manufacturers all over the world who all have varying levels of quality control and safety standards. This affords GREE absolute control over design, performance and quality.

GREE Eco-Cool - Shore Power AC

With soft-start and proprietary compressor technology, the GREE Eco-Cool boasts a remarkable 30%+ efficiency compared to the 20-25% efficiency of other shore-power units; showcasing a paradigm shift where efficiency and performance converge. With this level of efficiency, it rivals the power draw of higher output DC-powered units, as detailed below.

Nomadic X3 - DC Power

In contrast to the GREE Eco-Cool shore power unit, we will also take a look at the Nomadic X3 DC powered unit, a premium priced, creatively marketed, and enthusiastic novice in the marketplace. 

Analyzing Driving Factors for this Product Comparison

The decision to invest in a DC powered air conditioner over an AC powered counterpart hinges on a delicate balance between efficiency gains, cooling performance, and upfront costs.

While lower output DC-powered units like the Dometic RTX 2000 still offer substantial efficiency gains over the GREE unit, higher output DC-powered units like the Nomadic X3 display few advantages.

In the following sections, we explore key metrics such as energy consumption, cooling capacity, noise levels, and upfront costs to provide valuable insights into the performance differences between the GREE Eco-Cool and the Nomadic X3.

Key Efficiency Metrics

• Energy Consumption
• Cooling Capacity
• Noise Levels

Performance of off-grid rooftop air conditioners is evaluated based on several key metrics, which include energy consumption, cooling capacity, and noise levels. Lower energy consumption indicates higher efficiency, while higher cooling capacity ensures adequate cooling performance, particularly in hot climates. Additionally, minimizing noise levels contributes to a quieter and more enjoyable indoor environment during operation.

Test Results

The tests in the following infographics were performed by an independent test lab. All test procedures and conditions were controlled to maintain equal environments and an apples-to-apples comparison to monitor temperature pull-down and runtime. The air conditioning units were installed in their factory default state and set to Auto mode with a set point of 75F. The internal chamber was sized to approximate the interior volume of an extended wheelbase van. A nominal and equivalent heat load was placed inside the chamber for each test to simulate real world conditions. Interior ambient air temperature sensors recorded how effectively the air conditioning units distributed and cooled the air. Each test was timed to document the runtime until the 200Ah battery source was exhausted or until the low voltage cut-off was reached.

 Download Spreadsheet of Test Results

  Download Spreadsheet of Test Results

Per the above infographics, of course the actual temperature inside a space undoubtedly impacts comfort. Equally important, though, is the significance of relative humidity. This cannot be overstated. In environments such as RVs or camper vans, where occupants spend prolonged periods, maintaining an optimal balance between temperature and humidity is paramount for well-being. High humidity levels can exacerbate discomfort, leading to a clammy feeling, increased perspiration, and a heightened perception of warmth, even at lower temperatures. You'll notice both units initially increase humidity in the air. This is due to the cooling of the air inside a sealed chamber. The air gets cooler while the moisture content remains relatively the same. That is, until the evaporator reaches a cold enough temperature for the moisture in the air to condense and freeze onto the evaporator. We can see this takes some time for the Eco-Cool to achieve but there is a steep drop once the Eco-Cool catches up. The X3 on the other hand continues to climb, indicating it is either insufficient in cooling the air enough for it to condense on the evaporator and/or the evaporator is not cold enough to freeze the moisture and thus remove it from the air. 

You'll notice above where the GREE Eco-Cool excels in both temperature control and humidity management. 

A chamber at 85F (like with the X3) and 29% humidity is going to be far less comfortable than a chamber at 77F and 25% humidity. An environment at 85F and 29% humidity has more water vapor content in the air than a chamber at 75F and 40% humidity! (0.511 g/m^3 vs. 0.425 g/m^3).

Achieving an ideal balance of temperature and relative humidity fosters a comfortable and healthier indoor environment.

What's more, while the X3 shows a slightly longer run-time on 200Ah, in order to achieve an 8-hour runtime for both units, three 200Ah batteries are required for either unit for a total of 600Ah, a rather typical capacity for a RV or van intending to be off-grid.

With 600Ah, the X3 can be expected to run for 11 hours and 42 minutes straight. The GREE Eco-Cool on the other hand will run for 12 hours and 9 minutes. All the while being 10 degrees more comfortable, reducing the humidity, and reaching your desired set point faster.

You may be asking, ‘how is this possible when the X3 ran longer on 200ah?’. Thanks to the Eco-Cool’s large cooling capacity and efficiency, the compressor starts cycling after reaching the set point. This cycling reduces the energy consumption to near zero for several minutes at a time, which adds up over the course of an extended run. The X3 on the other hand runs full-tilt, struggling to maintain the temperature.

Noise Level

In an RV or camper van, the noise level of an air conditioner holds significant importance due to its direct impact on overall comfort and living conditions. Unlike traditional homes, where external noises may be masked by thick insulation or distance, the confined space of an RV magnifies any sound produced by the air conditioning system. Excessive noise can disrupt sleep patterns, hinder relaxation, and impede conversation, leading to heightened stress and discomfort during travel or downtime. Moreover, in outdoor settings where the serenity of nature is cherished, loud air conditioners can disturb both occupants and nearby campers, detracting from the tranquil ambiance sought after in recreational experiences. Therefore, opting for air conditioning units with low noise levels ensures a more peaceful and enjoyable environment within the confined quarters of an RV or camper van, enhancing the overall quality of the travel or living experience.

In our internal tests, we measured noise level of each of these units at a distance of 28.75". We measured both internal noise and external noise together. We believe both are important, as noted above, the external noise contributes to the comfort level of your neighbors where applicable. 

GREE advertises a noise level of 56dB on high.

At a distance of 28.75", we measured a reading of 65dB. The main reason for this increase is our included measurement of the external condenser fans. Most manufacturers advertise only the noise level inside the space. 

Conversely, we were not able to locate an advertised noise level on Nomadic's website. Our internal tests of the X3 unit measured a reading of 74dB on high. 

While this may seem like a minor increase, keep in mind that dB is a logarithmic scale. 74dB is almost twice as loud as 65dB. 

65dB is the approximate sound of a conversation. 74dB is like running a vacuum cleaner or lawn mower. 

Cost-Benefit Analysis and Conclusions

In the final section, we delve into a cost-benefit analysis to determine when the higher priced Nomadic X3 unit becomes economically beneficial over the GREE Eco-Cool based on efficiency and performance differences. By considering factors such as energy savings, cooling performance, and overall comfort, RV owners can evaluate the long-term value proposition of investing in a premium air conditioning unit.

Considering the cost premium of the X3 compared to the GREE, there is a staggering $3,184.00 difference in the upfront cost of the unit itself. In order to achieve an 8-hour runtime for both units, three 200Ah batteries are required for either unit for a total of 600Ah, a rather typical capacity for a RV or van intending to be off-grid.

With 600Ah, the X3 can be expected to run for 11 hours and 42 minutes straight. The GREE Eco-Cool on the other hand will run for 12 hours and 9 minutes. All the while being 10 degrees more comfortable, reducing the humidity, and reaching your desired set point faster. You may be asking, ‘how is this possible when the X3 ran longer on 200ah?’. Thanks to the Eco-Cool’s large cooling capacity and efficiency, the compressor starts cycling after reaching the set point. This cycling reduces the energy consumption to near zero for several minutes at a time, which adds up over the course of an extended run. The X3 on the other hand runs full-tilt, struggling to maintain the temperature.

Choosing an Eco-Cool unit leaves $3,000+ in your pocket to spend on other upfits for your van. More battery capacity perhaps? Or, how about adding heat? Let’s pause on the heat for a moment, because undiscussed in this post thus far is the Eco-Cool’s heat pump function. Air source heat pumps can be hit-or-miss depending on the exterior temperatures of where you intend to use them. Most will only provide ample heat down to about 40F. After that, you would need to resort to traditional resistive heating methods or sources that run on dino juice. However, the GREE Eco-Cool operates the heating function down to a best-in-class 26F ambient temperature. Power consumption for providing heat from the Eco-Cool is even more efficient than cooling, so you can expect similar or slightly longer run times while heating. With heating and cooling covered by the Eco-Cool, that extra $3,000 is looking like even more of a bonus. Add additional batteries and let all of your powered appliances benefit from the extra capacity. Add more solar or a secondary alternator to replenish the system quickly. Go off-grid longer. The possibilities are endless, and the choice is yours.

What's more, with GREE's dedication to trust and quality, the standard warranty is double that of Nomadic. 

Conclusion

Incorporating state-of-the-art soft-start technology, the GREE Eco-Cool unit emerges as the epitome of efficiency among its peers in the shore-power category. In our heat chamber tests, the Nomadic X3 DC-powered unit clocked in at a meager 20% increase in run-time on 200Ah of lithium batteries compared to the GREE Eco-Cool rooftop unit. While the X3 ran for 20% longer, the GREE maintained a far lower temperature and humidity level, which ultimately is the whole point. Given this information, the X3's substantially higher price tag, coming in at over three times the cost, raises a critical question of value proposition.

Moreover, empirical data reveals that the GREE Eco-Cool unit consistently outperforms the Nomadic X3. Thus, while the allure of enhanced efficiency for a short period of time may sway some towards the Nomadic X3, the tangible benefits do not justify the premium cost for most users, highlighting a tipping point where the incremental efficiency gains fail to offset the exorbitant price differential.

HONORABLE MENTION

• The slimmer width of the GREE unit ( 28.3” ) allows for a 100W slim solar panel to be installed on both sides of the unit, maximizing your roof space: https://rackupgo.com/products/go-power-slim-100w-solar-panel
• GREE's standard warranty is double that of Nomadic at 2 years vs. 1 year.