Off-grid, RV & cabin
Enter your cooling method and daily hours. Compare evaporative cooling against mini-split AC, and the solar panel wattage each one needs.
How it works
Step 1
Evaporative cooling and mini-split AC differ enormously in energy draw.
Step 2
Peak summer cooling often runs most of the daylight hours.
Step 3
Compare your choice directly against the other cooling method for the same hours.
A 300-watt evaporative cooler running 10 hours a day adds about 3,000Wh, while a small mini-split air conditioner running the same hours adds roughly 4,500Wh, about 1.5 times more energy for the same cooling duration. Both are substantial loads, and cooling is typically the single largest summer draw in a desert off-grid system. The panel degradation calculator takes the same inputs and works through the next step.
Evaporative coolers work by evaporating water to cool air, a process that needs only a fan and a small water pump rather than a power-hungry compressor doing the mechanical work of refrigerant-based cooling. This makes them dramatically more efficient than air conditioning in terms of electrical draw, but they only work well in genuinely dry climates, since evaporation slows and cooling effectiveness drops sharply as humidity rises.
Evaporative cooling loses effectiveness as humidity rises, so a desert location with occasional monsoon humidity, or a climate that isn't reliably dry year-round, benefits from a mini-split's consistent performance regardless of humidity, despite its notably higher energy cost. If your desert location sees a genuine humid season, factor that into your cooling choice rather than assuming dry-climate performance holds all year. the Department of Energy's Energy Saver guide covers the basics of how mini-splits and other AC systems are sized and rated.
Even an efficient evaporative cooler's 3,000Wh daily draw is roughly 8 times a typical fridge's daily load, making cooling the dominant summer load in most desert off-grid systems by a significant margin. Underestimating or skipping this figure in a load list is one of the most common sizing mistakes for desert off-grid builds, since a fridge-scale mental model badly understates what cooling actually needs. Electricity cost assumptions used throughout draw on EIA's data on what drives electricity prices.
Roll the cooling number into your total load list with the rest of your appliances, and run the cabin summer only use sizing tool if cooling is the main reason you are building an off-grid system at all. Desert heat hits both sides at once: it cuts panel output while it pushes cooling demand up, and the desert heat impact on output calculator in our performance and output tools isolates the output side, while the panel degradation calculator in our maintenance and lifespan tools accounts for the way heat also speeds up panel wear over time. Your panels can only charge what your battery can hold. The battery charge time from solar calculator in our Battery & Storage section can help you size the bank for your actual daily load.
Questions Your inverter has to handle the biggest load you will run at once. The quick inverter size estimator in our Inverters & Equipment section can help you size it for your actual appliances.
A 300-watt evaporative cooler running 10 hours a day adds about 3,000Wh, while a small mini-split air conditioner running the same hours adds roughly 4,500Wh, about 1.5 times more energy for the same cooling duration.
Evaporative coolers work by evaporating water to cool air, a process that needs only a fan and a small water pump rather than a power-hungry compressor. This makes them dramatically more efficient than air conditioning, but only effective in genuinely dry climates.
Evaporative cooling loses effectiveness as humidity rises, so a desert location with occasional monsoon humidity or a climate that isn't reliably dry benefits from a mini-split's consistent performance regardless of humidity, despite its higher energy cost.
Yes, often by a wide margin during summer months. Even an efficient evaporative cooler's 3,000Wh daily draw is roughly 8 times a typical fridge's daily load, making cooling the dominant summer load in most desert off-grid systems by a significant margin.