By Rehan Iqbal
Whether you’re a prepper, an outdoor enthusiast, or you work in remote locations, a self-supporting water generation system is an enticing option. What do you need to set up your own portable solar-powered water generation system? That depends on a lot of factors, including your water generator, your climate, the amount of water you need, and your options for solar power. With so many factors at play, there’s no one solution that works for all use cases. Here’s what you need to consider when you build a solar power system for your AWG.
One of the great things about atmospheric water generators is their ability to capture water anywhere that has humid air. You don’t need to dig a well or have access to surface water, and you don’t need to worry about water testing. Everything you need for clean, safe water is built in the machine. When you combine a water generator with a battery and a set of solar panels, you can make clean drinking water in the most remote locations. It’s also possible to build a completely portable AWG and solar power setup, so you can have temporary water access wherever you are.
AWGs don’t deliver water on demand. Instead, they gradually condense water from the atmosphere, then pump this water through a filtration system and into a storage tank. Once the clean water tank is full, you can shut it off. This lets you use the generator while sunlight is available, building up a water supply to last the rest of the day.
The amount of moisture the air can hold increases with temperature. That means these machines work at peak efficiency during the day, and particularly in the afternoon, when temperatures are at their highest. This is also when the sun is at its peak, maximizing your solar panels’ efficiency.
What is a “Solar Ready” AWG?
Water use has a huge impact on the power demands of your AWG. In turn, this determines how much power you’ll need for your solar power setup. You probably won’t be able to directly replace all of your water needs with an AWG, but you can make choices that keep the size and cost of your system reasonable without sacrificing health or comfort.
According to an EPA WaterSense study, the average American uses 70 gallons of water per day. Here’s how many gallons each activity uses:
Obviously, if you’re using an AWG, you probably aren’t using water like you do at home. Water leaks aren’t an issue, when the water only needs to travel from the evaporator through some filters to a storage tank. You also aren’t going to wash clothes or flush toilets with your water. This study found about 30% of each person’s water use happens outside for things like washing vehicles and irrigating lawns. Take all this into account, and your average water use is already cut by more than half. Instead, the best way to look at this is to figure out how little water can you get by with, then add as much as you’ll need to be comfortable.
For basic survival, we need to consume at least one liter of water per day. However, water consumption should be closer to 3.7 liters (1 gallon) for men and 2.7 liters (0.7 gallons) for women per day for long term health. This includes all sources of water, including drinking water, other drinks and food. On average, 20% of our water consumption comes from food, while the rest comes from drinks. Our need for water increases with physical exertion, especially during the summer. You should expect to need one extra liter of water for every two hours of work.
Of course, we use water for more than just drinking. It’s also used for cleaning and sanitation. The general guideline for camping is two gallons per person per day. This gives you enough water to prepare meals and do some basic cleaning and hygiene.
Want to take a shower? Your AWG can’t pressurize water, so you’ll need a camp shower. These vary in output and design from kitchen sink sprayers to full shower heads. Water use ranges from about half a gallon to one-and-a-half gallons per minute. If you only use enough water to wet your skin and rinse yourself off, you will use somewhere between 2-7 gallons of water, depending on the flow rate.
What Do I Need for My Solar Power Setup?
AWGs need alternating current to run, while solar panels generate direct current. To get AC power, you need a power station. This device uses solar panels to charge an onboard battery. Circuitry inside the station converts that battery power into different forms, including alternating current. By adding a battery to the system, you also add a buffer, maintaining consistent power to the AWG.
Adding an extension cable gives you more options for setting up your power system. Your AWG needs to be under a roof, tent or awning to protect it from rain. That’s because these machines run so cold that water can freeze on contact. Using a cable lets you position your panels for maximum power while keeping your generator in a safe location.
What Features Should I Look For in a Solar Generator?
The power station needs a pure sine wave inverter. The AWG is designed for household power, which, in the U.S, gradually switches polarity 60 times per second. Standard power station inverters switch between negative and positive polarity abruptly. While this is fine for electronics, electric motors can’t run on this type of power. If you plug an AWG into a power station with a standard inverter, the compressor won’t start.
Speaking of electric motors, they’re reactive loads. They need two to three times as much power to start as they do to run. Make sure your power station can handle these brief spikes in load. Power station output is rated in peak load, the maximum amount it provides over a few seconds, and sustained load, the power it provides over long periods of time.
How Much Battery Power Do I Need?
Power requirements for atmospheric water generators are usually quoted in amps, while solar generators and panels quote power in watts. To convert from amps to watts, multiply the number of amps by the voltage, 120. For example, a 15 amp AWG uses 1,800 watts of power. Keep in mind that power figures are usually rounded up to get even numbers, so actual power draw may be lower than what’s quoted. For the most accurate information, connect your AWG to an electricity usage monitor. This device shows power draw in real time, so you can see exactly how much power your machine uses while running and during startup.
The effectiveness of an atmospheric water generator depends on humidity and air temperature. If you run your AWG in hot, humid weather, water production can be up to four times as fast as running it in cool weather with little moisture. If you plan on using your water generator as a source of water at your lake cabin during the summer, you’ll need far less power than you would for an AWG that you’ll use in emergencies throughout the year.
Batteries are rated in watt hours (Wh) or amp hours (Ah.) As you may guess, Wh is a measurement of watts over an hour. Multiply the watts your AWG uses by the number of hours you need to run it each day, and you’ll get your total required watt hours. To convert this to Ah, divide Wh by 120, the voltage used by your water generator. Converting the DC power from the battery to AC power isn’t 100% efficient, and there are other problems that hinder output, like extreme temperatures. A good rule of thumb is to use a solar station with a battery that only needs to use 85% of its rated capacity to power your water generator.
How Many Watts of Solar Capacity Do I Need?
Now that you know the total watt hours you need for your system, you would think you could work out how much solar panel capacity you need to charge the battery over a specific time period. However, it’s not quite that simple. Usually, the rate that the battery can charge will be the limiting factor. For example, if you have a single 100 watt panel that charges the power station in 15 hours, adding a second panel may drop this time to 9 hours.
You may have double the power, but because of battery limitations, charging time only drops by about a third. Fortunately, this is increase is linear, so you’ll still cut charging times as you add panels up to the power station’s limit. For the most accurate information, check your power station’s manual. The manufacturer’s internal testing should be close to what you’ll experience in real world use.
There’s another factor at play: weather. The wattage rating is the output for ideal conditions. If the panel is shaded, it won’t produce as much power. If it’s cloudy, there’s less light reaching the panel, decreasing power by 10-25%. Output also goes down when the panel gets hot. On average, efficiency drops by one percent for every degree above 90°F.
How Do I Connect My Water Generator to My Power Station When They Need to be Separated?
It’s easier to use a long extension cord between your AWG and your power station, instead of using extension cables between the station and your solar panels. This cable needs to carry a lot of power in outdoor conditions. This is easy to overlook, causing problems you may blame on the power station or AWG.
The easiest way to choose the right extension cable is to look at what’s printed directly on the cable insulation. This labeling follows rules laid out by the National Electrical Code. Most outdoor extension cables will have some combination of these letters on them:
For example, a cord labeled “SWTO” is a standard cable that is built for outdoor use, has a thermoplastic insulation housing, and is oil resistant. When you select an extension cord, you want something that is rated for outdoor use, but the insulation material doesn’t really matter. If you’ll run your AWG in your garage, or anywhere else where it may be exposed to petrochemicals, get an oil-resistant cable.
To choose the right size of cable, you need to look at another AWG: American Wire Gauge. This numbering system goes up as the wire gets smaller. For a 25 foot extension cord, you need 14 gauge wire. With a 50 foot cable, you need a 14 gauge cable for a 15 amp generator, and a 12 gauge wire for a 20 amp generator.
Using a smaller gauge wire increases resistance, which lowers voltage. This reduces the compressor’s torque, which can keep it from starting. Gauge is often listed next to “(AWG)” or alongside the number of conducting wires in the cord. “2” is used on cords with a two prong plug, and 3 for cords with a three prong plug. If you look at the housing, you may see “12(AWG)” or “12/3” for a 12 gauge, three conducting wire cord.