Solar Powered Dehumidifier Help

Hey guys. My dad, my brother and I have been pondering the idea of a solar-powered de-humidifier. So, it would charge using the sun's rays, and then use its power in the dehumidifier. This is something that could be used in parts of Africa with 100% humidity, and not alot of water.

It is the perfect tool for anyone to use to obtain fresh water, by harnessing the sun's rays. We have a dehumidifier, and we really want to make it Solar Powered. We just need help in the way to power it.

Would we charge a rechargable battery using the Solar Rays, or would we run it on solar power alone. The solar panel that I have been looking at is the Sunforce 50022 5 Watt Solar Battery Trickle Charger.

Do you think that that Solar Panel is good enough? It is 5 Watts, so how would we connect it to our dehumidifier? This was the solar panel in the most recent PopSci used in the How 2.0 section. It is used to charge personal electronics.

Thanks in advance.

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MatthewD692 months ago

a solar still is installed on the earth and captures water evaporating from the ground. The sun's heat speeds up the process.

Solar cell power is barely half as efficient as a stirling engine run off the heat of the sun, which you can store in an oil reservoir that cycles through black painted heating tubes you can stick on your roof, with that angle and the reservoir properly positioned, as the heated oil rises it sucks in cooler oil and eventually heats the whole reservoir. Oil retains most of its heat through the night. The stirling engine runs on the temperature difference between two locations on the engine, enough to mechanically or electrically power a dehumidifier, air conditioner, or even a power generator. Stirling engines are very scalable, yet even one a few inches tall can run off the heat of your hand. With a fresnel lens heating up your oil to just below smoking temperature, you could have a few stirling engines running in tandem, or one for each device. Coupled with geothermal heat exchange, you could ditch the oil and just use the temperature difference between groundwater and the air, and 21 feet in the ground, the temperature there remains constant all year round, equal to the average temperature of the air at ground level. All sustainable energy comes from the sun anyway, might as well be efficient... That stirling engine can cost you a lot of money. You'll likely want to find plans online and make it yourself. Geothermal is good for air conditioning, 1/4 the running costs of a standard a/c according to my parents who have this in their home in gulf coast alabama, but I don't know if it has enough power for generating power, unless you know or learn how to eliminate lenz law magnetic drag, which has been done in several ways. As you can guess, it requires rewiring your generator's coils, a nightmare if you don't know what you're doing, but it more than doubles the energy output or requires half the input power by reducing induced magnetic eddy current drag to zero.

kimseymd6 months ago

I don't understand how a solar still will make new2 drinkable water without putting water into it first where a dehumidifier or AC unit would get water from air.

epte1 year ago

If you have a hillside, consider creating a qanat. Used in Iran, wanats are a way of exchanging heat with the earth, drawing in hot, moist air from vertical shafts. When the hot air contacts the cool earth, the water condenses out, cooling the air. Bot the water and the cool air flow out along a horizontal tunnel, sloped slightly downhill. The cooler air, flowing down, creates a vacuum and sucks in more hot air through the vertical shafts. Some oases were created at the outlet of a qanat.

When people put in earth tubes (ground coupled heat exchangers), commonly you add weep holes to let the water that condenses seep out of the pipe into the ground. Qanats instead harvest this water.

Then plant your windbreaks to funnel your humid air into your qanat to amplify the effect.

hank3 years ago
So -- any progress with this? It's still needed. Anyone who's put on a "cool roof" has discovered that they need a thick layer of airtight insulation under the "cool roof" layer -- without that, the cool surface exposed underneath accumulates condensation and the attic humidity goes up and stays up.

We found ours rising up into the dry-rot-danger range, because nobody in our area understood the need for insulation in moderate humid coastal climates.

(it's well understood in places that go below freezing during the winter, because ice lifts up the parts of the roof and breaks things -- but those also are places with extremely dry wintertime air and hot summers, so the roof dries out).

So -- looking for solar powered dehumidifier help. Lots of ideas, mostly several years old - but I haven't found anything working yet.

The calculations above are the most useful info I've found so far!
jburrows54 years ago
I love this thread. So much great, knowledgeable stuff.

But, a Solar Still takes a lot of setup. If electricity were available, wouldn't it be worth it to use a dehumidifier? The reason I ask is that the output is incredible.
NachoMahma9 years ago
. Basically a dehumidifier is just a small air conditioner - water condenses on a cold spot. A Peltier junction junction ought to work. . I'll _guess_ it will take ~50-100W to produce enough water to make it worthwhile. You should be able to find tables/formulae online that will use RH, deltaT, surface area, amount of water expected, etc to compute Wattage required. . You can wire the solar cells in series and/or parallel to get the desired voltage/current. . Whether or not it will need to run 24/7 (requiring a battery), depends on how much water you need to make per day and the output of the unit. . . To use your 120VAC home dehumidifier will probably take a lot more than 5W. There should be a label on the DH specifying the W (or maybe A; if so multiply V (120) times A to get ~W) needed. . To connect the solar cell to the home DH, you will need an inverter, which will rob a lot of power through inefficiencies, which will require more solar cell. Better off using a low-volt DC DH (Peltier) if you will be using solar cells.
I had this idea also. I do work in Haiti and would like to see about the feasability of making a household unit for drinking water purposes. Can anyone lead me in the right direction.
Can anyone tell me why compressed air is not used as a refrigerant? Carbon Dioxide, Ammonia, or Propane, I've seen them used for heat pump/refrigeration machines instead of "freon". But a tank of compressed air (with or without water vapor) can be released into a radiator or cooling coil, and then safely vented/returned to the atmosphere if need be, and it WILL be cold, so condensation should happen. Ideally a wind powered air compressor should be a very powerful and useful machine in moderately windy places.
. Efficiency. Freon, et al, use the heat taken in or released when it changes from a liquid to a gas and vice versa to transfer heat. Oxygen and Nitrogen have relatively high boiling points and are difficult to compress back to a liquid.
VIRON9 years ago
Look up "solar still". It doesn't need electricity.
. Not that a solar still is a bad idea, but I would think that a photo-voltaic powered unit would be able to produce a LOT more water per mass and volume than one that depends on ambient air for cooling. . And it would be almost as simple as a solar still. The most complicated part of a PV powered Peltier unit would be an optional fan.
Solar stills are by far cheaper to make, cheaper to install, easier to run, easier to maintain and easier to scale up. The most complex part of a solar still is the transparent window, and that just needs to be a sheet of reclaimed polythene. Why do you think survival kits contain solar stills instead of PV units?
> Why do you think survival kits contain solar stills instead of PV units? . Tradition?
Because they work better.
CameronSS9 years ago
My dad and I just had a quick discussion about this. We have a relatively small dehumidifier down here in my basement lair. It's about 850W, and when we first moved in, the basement humidity was about 80%, and it produced less than a gallon a day. It also generated heat. Also, 850W at 120VAC is 7.1A. However, it'll take about 15A to first start, so you would need closer to 1800W to start. A friend covered her entire barn roof in solar panels, and it's about 1500W. His arguments were: 1) rather than using inefficient PV cells to run an inefficient dehumidifier, why not use a solar collector/still and eliminate pretty much all the parts that could fail thousands of miles away from their source, and 2)If you insist on using an electromechanical device, why not use an air conditioner? By sacrificing a small amount of efficiency, you get a device that still produces water, but cools instead of heats. So basically, 5W will distill you about a drop each day, and will further heat the air. It'll take darned big array of solar panels to run a dehumidifier.
> So basically, 5W will distill you about a drop each day . Wow! My guess was WAY off.
Everyone always seems so surprised at how much power it takes to run so little...and how hard it is to make that much. It takes a LOT of power to run a dehumidifier, or an A/C unit. Although, our whole-house unit, when we first turned it on this summer two weeks ago, produced three gallons in the first three hours it ran.
Brennn10 (author) 9 years ago
Bump, Bump, Bump it up! Sorry, I usually do not bump topics, but this is one I am serious about.