Can You Run an RV Air Conditioner with Solar Power: The Reality Behind the Feasibility
The question arises: Can I run my RV air conditioner with solar power? The straightforward answer is yes, but only with careful planning and robust systems. The possibility hinges on your solar power setup's capacity, the air conditioner's power requirements, and the inclusion of a reliable energy storage solution.
Understanding the Feasibility
The feasibility of running an RV air conditioner with solar power depends on the air conditioner's energy consumption and the total available power from your solar setup. While modern technology might make it feasible, the economics often make it less attractive than other alternatives.
Challenges in Implementing Solar Power for RV AC
Complex control systems and energy system coordination are essential to make this work efficiently. Modern air conditioners with variable-speed compressors and brushless DC (BLDC) fans are more suitable for solar-powered systems. These components help in energy management and ensure efficient operation, even under varying solar conditions. However, achieving this requires a sophisticated control system that can switch between grid, battery, and solar power.
Back-Of-The-Envelope Calculations
Let's delve into a detailed example provided by a retired electrical engineer to understand the practicality of running RV air conditioners with solar power. Consider the following example:
Load Requirements and Inverter Analysis
A 37-foot motorhome with two air conditioners, each drawing 13A at 120V AC, totals 26A, or 3.12 kW. To run everything in the RV, an 8-kilowatt generator is needed, providing both the air conditioners and additional appliances like an electric water heater, refrigerator, and microwave. For a purely solar-powered system, the engineer estimated that around 3.5 kW of power must be available, leading to an inverter requirement of 8 kW.
Solar Panel Array Design
A typical 8 kW inverter designed for this application, costing around $5700, would require a solar power input of 10.7 kW to meet its operating needs. With a power factor and efficiency considerations, the solar panel array needs to supply at least 223A at 48VDC. A high-efficiency monocrystalline solar panel capable of 450W with a maximum power output of 13A would be needed. These panels would need to be stacked in pairs to achieve the necessary voltage.
Space and Cost Constraints
Designing a suitable solar panel array for the RV's roof presents significant space and cost challenges. Even with cleverly designed foldable frames, only about 36A of current can be realistically provided. This is far from sufficient to run the 3.5 kW needed, requiring a significant battery bank to bridge the energy gap.
Energy Storage and Battery Considerations
Battery technology plays a crucial role. High-drain, deep cycle batteries are essential, especially when considering weight and long-term performance. Lithium-ion batteries are recommended for RVs due to their efficiency and lighter weight. A battery bank consisting of four 12V 135AH batteries, costing around $10,800, can provide about 1.15 hours of operation under ideal conditions. However, recharging times could be significantly longer, leading to a 33% duty cycle for the air conditioner.
Cost Estimation
The total cost for this system, including the inverter, solar panels, batteries, and controllers, can range from $15,400 to $30,800. This makes it less economical compared to a genset, which offers continuous, reliable power and better performance.
Conclusion
While running RV air conditioners with solar power can be feasible, it requires a significant investment in both technology and energy storage systems. The practicality is often outweighed by the economics, making gensets a more attractive and efficient option for many RV owners.