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Forum Index : Solar : Solar Clothes Dryer
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MacGyver Guru  Joined: 12/05/2009 Location: United StatesPosts: 1329 |
You know what they say about idle hands, right? Well, pursuant to that line of thinking, here's my latest mischief: I've built an active solar-fired clothes dryer. I'm retired now and even though I can afford to send my clothes out to a commercial laundry, I'd rather do them myself. I've become somewhat of a "minimalist" of late. That's the attitude I've adapted since retiring and looking down the road several years, everything I can invest in now, which will reduce my future costs is a good deal and I'm on it like a chicken on a bug! Here goes: I started out by constructing a long box out of wood. The idea is to cover the box with clear polycarbonate sheeting and use the properties of solar absorption and reflection to manipulate the sun's rays. The goal is to create an internal convection current, which draws in cool air at the bottom and causes it to rise as it gains heat from both direct solar radiation as well as from internally-radiated heat. The heated air passes over the wet articles of clothing, drawing off the moisture and then exits through small holes in the top of the unit. The whole thing operates standing vertically, leaned against the side of my land yacht. Here's a piture of the finished product leaning against my car: 
The whole thing measures 6" deep, 25" wide and 96" (8') tall. Following are the particulars of the build: 
The bottom half is backed with luan and painted to retard destruction from moisture. I laid a 1" layer of construction-grade foam wall insulation in first. This will insulate the back of the unit and prevent heat loss from the metal panel in front of it. 
Here's the top portion of the unit with nothing but paint thus far. I used flat black latex paint. 
A 4-foot x 23 1/2" panel of corrugated sheet metal (patio covering) is held in place against the insulation sheet using a sheetrock screw driven in from the outside and left overlapping the edge each side; one at the top, one at center and one at the bottom. This shiny surfact will soon be blackened in order that it will absorb heat from the sun's rays. 
Here's a shot of the lower metal panel installed in the unit. 
This is that same panel painted flat black. I used spray-on flat black paint. 
This shows how I marked a line across the upper metal panel after first installing a cross bar (next picture). This is intended to hold the top metal panel off the front of the unit and create a pocket of insulated air. The idea here is to have the bottom panel create a convection current, while the top panel, being locked onto a front insulated air pocket, gets hotter than the hubs of hell and radiates that heat from the still-shiny back side and across the air space behind it. That same air space is also occupied by wet clothing that is suspended on a wire lattice to keep it hanging with a small air space each side. Look at the pictures and it'll all make more sense.. 
This picture shows that "unpainted" cross member talked about in the previous paragraph. It serves only to hold the metal off the front surface, creating a sealed and therefore insulated air pocket. 
This shot shows the top metal panel installed. This side (the inside) will remain shiney so when its other side (painted flat black) is exposed to sunlight, it gets hot and radiates that heat to the wet clothes. 
The front clear panel is polycarbonate sheet intended for a greenhouse roof. It stands up to direct sunlight without becoming discolored or brittle. The ends of the panel are stuffed with neoprene insulation and screws secure it to the top of the dryer. I put a screw in every valley as well as every several inches up each side of the entire box. 
A small metal handle was installed on the top end to facilitate moving the thing around. In a later photo, I'll show you how I've attached two small wheels just a bit above the bottom edge. This lets me rest the unit on its bottom edge while things are drying, but also allows me to wheel the beast around by tilting it back far enough that the wheels contact the cement. Those two small circles each side of the handle are exit holes drilled in the top side. This allows the heated air within to exit to the atmosphere. There are three inlet holes on the bottom side panel that allow cool air in from the bottom thus creating an internal convection current. 
This is the unfinished door to the thing. This is where the wet / dry clothing is placed / retrieved during use. I hinged it top and bottom as well as built an internal perimeter framework to keep it from warping. There is a handy latching mechanism that locks the door closed during use as well as when I move it around; a bent-over nail! 
Here's a shot of the unfinished inside door. That block of wood in the center is backing for the screws, which hold another handle to the front of the door's outside. The plywood I used for the door was only about 1/4" thick, so I had to beef it up enough to give the screws a good landing spot. 
Here are those two little wheels I mentioned earlier on. 
This is one up close and personal. 
This shows the painted inside of the door. Note the wire latice I installed to keep the moist clothing off the back door. Remember, this thing operates sitting at a slight tilt. I wanted to assure there was an air space front and rear of the hanging clothing to facilitate warm air passage both sides. Also, note the two wires on the right hand side of the picture. These are inside the unit and are there to receive a clothes pin or coat hanger. Hmmm . . . I wonder if a plastic hanger will melt; I'll let you know. That's about all there is to this project. Although the paint was barely dry, I stood it up behind my car for about ten minutes, then opened the door to check the temperature. Hot as hell! The upper, front panel was hot enough to be very uncomfortable when touched and there was definitely an active air current escaping through the exit holes atop the unit. I'd say job done! . . . . . Mac Nothing difficult is ever easy! Perhaps better stated in the words of Morgan Freeman, "Where there is no struggle, there is no progress!" Copeville, Texas |
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| VK4AYQ Guru Joined: 02/12/2009 Location: AustraliaPosts: 2539 |
Hi Mack That will get hot enough to cook the elastic in your jocks. Bob Foolin Around |
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| MacGyver Guru Joined: 12/05/2009 Location: United StatesPosts: 1329 |
Hi Bob. You might be right. 
I put a load of laundry in to "cook" this morning, but there were no socks. Luckily for me, I wear tube socks, so there's probably less elastic than in the regular models. This is going to be another one of those hide and watch things. Most of the stuff we do here on the 4m is trial and error anyway, so if (when!) I discover I've overdone it, I'll likely have to modify things. Just a few minutes ago I checked on the first load and it was so hot inside I "snuck up" on touching things. My guess is this contraption is headed for the band saw. My best guess so far is I need about half the amount of surface area. That's alright; that'll give me two small units instead of one behemoth. As I think about it, a smaller one (two) will be easier to move around and store. There's always something good in all we do. I'm the eternal optomist; not easily discouraged. . . . . . Mac Nothing difficult is ever easy! Perhaps better stated in the words of Morgan Freeman, "Where there is no struggle, there is no progress!" Copeville, Texas |
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Tinker Guru Joined: 07/11/2007 Location: AustraliaPosts: 1904 |
Mac, why not increase the airflow through that contraption? Those tiny air holes look much too small for me. I also would fit a recycled 12V computer fan at the bottom to push air inside and power that from a small 12V solar panel on the top. Since it only dries clothes when the sun shines on it the fan runs automatically when needed. Klaus |
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Greenbelt Guru Joined: 11/01/2009 Location: United StatesPosts: 566 |
Hey Mac., Tinker has it right, IMO, Air is what dries clothes, the heat just lowers the relative humidity so the air can hold more water. You have a working design here if you let more air pass through it. Here's an Idea. Kind of ugly but may work. -------Cheers, Roe 
This was a shop heater in a huge open area, Lots of radiation heat. Time has proven that I am blind to the Obvious, some of the above may be True? |
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| MacGyver Guru Joined: 12/05/2009 Location: United StatesPosts: 1329 |
Crew I think everyone is right about the air flow. When I built it, I didn't want all the heat to escape and it doesn't. Hell, you could bake a cake in the thing it gets so hot now. I'll try opening it up a bunch. What I've really got in mind is to make it only about 5-foot long instead of 8. It's a bit too unwieldy to move about and store. Also, if it's a bit smaller, it will fit more places as the seasons change and the sunlight comes from different directions. Thanks for all the comments. I'll keep at this until it's both a workable as well as feasible project. 
By the way . . . I took Father's Day morning off and went to the beach with my metal detector. I found a considerable amount of pocket change and a little clump of gold jewelry! 
. . . . . Mac Nothing difficult is ever easy! Perhaps better stated in the words of Morgan Freeman, "Where there is no struggle, there is no progress!" Copeville, Texas |
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fillm Guru Joined: 10/02/2007 Location: AustraliaPosts: 730 |
You will be able to dry your colths in the coin drier now.  PhillM ...Oz Wind Engineering..Wind Turbine Kits 500W - 5000W ~ F&P Dual Kits ~ GOE222Blades- Voltage Control Parts ------- Tower kits |
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| Jarbar Senior Member  Joined: 03/02/2008 Location: AustraliaPosts: 224 |
Mac, if you remove the neoprene insulation inserts in the corrugations you would get considerably more air flow at a lower temperature. Anthony. "Creativity is detirmined by the way you hold your tounge".My Father "Your generation will have to correct the problems made by mine".My Grandfather. |
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| Robb Senior Member Joined: 01/08/2007 Location: AustraliaPosts: 221 |
This will improve the air flow 
And no melted elastic
It does look like a good solar space heater though if you piped air inside from it. |
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| Tinker Guru Joined: 07/11/2007 Location: AustraliaPosts: 1904 |
Hey Mac, that's my shed key that you found! How did it end up on your beach Klaus |
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| petanque don Senior Member Joined: 02/08/2006 Location: AustraliaPosts: 212 |
but buying the commercial version is never the same |
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| MacGyver Guru Joined: 12/05/2009 Location: United StatesPosts: 1329 |
Crew Thanks for all the replies; I got a good chuckle. @ Jarbar: The reason I put the insulation in like that was to create an insulated air pocket. The idea was to make the thing get hot and keep it that way, while the air holes let air flow up the back side. Seems to work pretty well. I was going to "modify" it a bit this morning, but I was forced out of retirement for a friend's plumbing emergency, which took all day! Hey, what are friends for, right? Anyway, when I get the time, I'm going to make the encapsulated space half the size. That will open up the area behind the hot plate and give more room for more air to circulate. I'm also cutting the thing down to around 5 feet tall. The 8-foot version reminds me too much of the monolith in 2001 - A Space Odesy; it's just too big to work with. @ Tinker: I think I'll take you up on your solar panel and computer fan idea. It makes sense and besides, in the winter, the only feasible time to dry will be at noon and the thing won't be creating a draft at all lying down. Good suggestion; thanks. Oh, did I mention I'm working on building an electric assist for my mountain bike? If I could turn all my crazy ideas into cash, I'd be a zillionaire!
. . . . . Mac Nothing difficult is ever easy! Perhaps better stated in the words of Morgan Freeman, "Where there is no struggle, there is no progress!" Copeville, Texas |
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| Air Bender Senior Member Joined: 25/01/2011 Location: AustraliaPosts: 206 |
It may not be solar 
But at this time of year we dont get a lot of sun. We have another chimney that runs up beside this one in the next room. I have closed of the tops of the chimneys apart from where the flew goes though and knocked out bricks at the top opening up one chimney to the next. So we get a good draft going up the chimney with the flew then going down the other chimney into the next room. A few cloths horses in front of the fire place in the next room and cloths dry in no time at all. All the best Dean |
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| MacGyver Guru Joined: 12/05/2009 Location: United StatesPosts: 1329 |
Solar Clothes Dryer Revisited Thank you all for your comments thus far. I've taken them to heart and made some changes, the most noteworthy being taking Tinker's advice, adding a small 12-volt computer fan driven by a solar panel. Here's what I've come up with: 
I've also shortened the thing from 8 feet to 5 feet tall. This enables me to move it around and store it more easily. Here's a shot of it stored underneath my land yacht: 
Removing just 3 feet of length makes it easier than ever to move and store. Unfortunately, this has been the color of the sky lately: 
In May we call it May Grey. In June we call it June Gloom. In august and beyond we address it with four-letter explatives! 
Here's a shot from the back side. The door serves also as a prop and holds the unit in an upright position for loading and unloading. 
Here's a shot of the little fan, which is mounted on the inside. I took the picture from outside the box. 
Here it is from the inside. I attached the two wires to a bus plate, which is mounted above. The wires then run to a quick disconnect plug that came with the little solar panel ($19 from Harbor Freight). 
Here's an inside view looking up through the air-exit holes in the top. 
I reattached the little wheels about 3/4" above the bottom. This position allows me to tilt the unit back to wheel it around yet still have room to tilt it back onto a wall in a resting position to aim it at the sunshine while leaving the wheels out of contact with the ground. 
The solar panel attaches to the front side with a metal tang that slips behind a metal bar, which is mounted above the side of the box forming a little slot. When the unit is stored, the panel lifts off and fits neatly into the bottom of the whole thing as seen here. Now, if only there were some sunshine, I'd have it made, but as you can see from the 3rd picture, the sky around here is anything but clear lately. I actually had to use my electric back-up for one hour last night in order to take a steaming-hot shower. The solar water heater works even when it's overcast, but not well enough to make the water as hot as I'd like it. The solar clothes dryer is dependent on absolutely CLEAR skies. I guess you can't win 'em all, eh?
. . . . . Mac Nothing difficult is ever easy! Perhaps better stated in the words of Morgan Freeman, "Where there is no struggle, there is no progress!" Copeville, Texas |
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| MacGyver Guru Joined: 12/05/2009 Location: United StatesPosts: 1329 |
Got Sun? This is a little update based on the fact that I woke up today to almost clear skies and SUNSHINE! 
Here, a load of laundry cooks inside the dryer. Running my fingers past the little holes in the "top" I can feel pretty hot air escaping. That's what we want, warm air FLOW removing the moisture. 
This is a tight shot of the little solar panel I used. I got it at Harbor Freight on sale. 
This shows how I drilled holes in a flat aluminum bar, then used a little nut between it and the dryer housing to create a "stand off" or slot. 
The solar panel came with two slots meant to "hang" the thing on two screw heads. I merely used those slots and a nut each to "jam" a piece of angle aluminum stock. This makes the "tab" that fits the "slot" on the dryer body. It holds it there securely, yet slips out easily when the laundry is done and it's time to stow it inside. I should mention that I also had to drill a hole in the case large enough to accommodate the quick-release plug in order to pass the wire to the inside where the fan is and not interfere with the door closing; it's a pretty tight fit. I think that's about it or as Forest Gump would say . . . well, you know! . . . . . Mac Nothing difficult is ever easy! Perhaps better stated in the words of Morgan Freeman, "Where there is no struggle, there is no progress!" Copeville, Texas |
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| MacGyver Guru Joined: 12/05/2009 Location: United StatesPosts: 1329 |
I thought I was done; but no! The thought occured to me that I, being somewhat of a Johnny Cash throwback--always wearing black, that I really didn't need that metal plate inside the dryer. My clothes are already black, so I yanked the metal plate out and wouldn't you know? It works even better. Truth be told, there's absolutely NOTHING better than a clothes line, but where I live there are "rules" and I can't have one. You'd think they'd complain of my nearly casket-sized and looking box, but no. Anyway, I unscrewed about a million screws, removed the black corrugated steel plate and put it all back together again. Next, I tossed in a wringing-wet pair of black levis (they were so dripping wet, the dryer's back panel board warped a little!) and in just under 3 hours, all the water had cooked out and the thngs were dry as a bone. A clothesline would likely have been a little bit faster, but by not much I'd bet. So, my thought is, I can finally put this project to rest. Time to build another little windmmill, eh? . . . . . Mac Nothing difficult is ever easy! Perhaps better stated in the words of Morgan Freeman, "Where there is no struggle, there is no progress!" Copeville, Texas |
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NathanM Newbie  Joined: 23/08/2011 Location: United StatesPosts: 5 |
Looks like a fun little project that works. When you aren't drying clothes with it, you could be making jerky with it. I'm sure it would work well although it would probably make your clothes smell like jerky from then on.  Need San Francisco electrician |
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| MacGyver Guru Joined: 12/05/2009 Location: United StatesPosts: 1329 |
UPDATE This axial-flux build I'm finishing is beating me up, so I decided to tinker with an old toy. I added another solar panel (12-volt @ 1.5 amp) and wired it in parallel with the existing one. I then removed the single side-mounted pancake fan and added three at the bottom of the dryer. Since the dryer almost always tilts off the vertical, heated air inside the unit rises naturally against gravity and putting the fans in the bottom was to augment that internal flow. The pictures show my favorite bath towel (green) inside drying. Fresh from the wringer, this towel will be crispy dry in no more than about 3 hours. I have two bath towels, (this is my favorite one cause it's thick and green, my favorite color). It's not like I'm operating a spa and have to hand out towels like business cards. Anyway, here are a couple pictures so you can see the new fans in action: 
This is the original solar clothes dryer with an added solar panel. I merely prop it against yard furniture to keep it almost perpendicular to Mr. Sol. 
This shot is a peek through one of several exhaust vents cut into the top of the dryer. My camera's shutter speed was such that it caught two of the fans' motion and stopped it. These are two of three little computer fans, each 12-volt. With the addition of the extra solar panel, these fans run like scalded dogs! Access to the clothing inside the dryer is through the rear. The entire top 9/10 of the unit is a hinged door. I didn't make it 100% because I needed to leave some stronger structural support on the lower end to hold things together. As goofy as this project is (at least I'm consistant!) it actually does a very good job of drying clothes. On days when there's not much sun, it still works, but takes a lot longer. There has to be clear sunshine for the little panels to generate enough clean power to run the fans. Once their "threshold" current requirement is made, they jump into action and spin like tops. . . . . . Mac Nothing difficult is ever easy! Perhaps better stated in the words of Morgan Freeman, "Where there is no struggle, there is no progress!" Copeville, Texas |
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| SURFFOILS Newbie Joined: 01/07/2014 Location: AustraliaPosts: 2 |
Hi Mac, , it's my first post from Sydney , Australia. Love your work, great idea and build. Ive got several sheets of polycarbonate and I wondered for years if it could be used to make a room heater, you know, prop it up in a window that gets sunlight and it could heat and reheat the interior.i even thought I could attach a few panels like this to the outside of the house on several sides and pipe the hot air inside. Or maybe not... but the first step would be in testing to see how hot it gets Vs the amount of sunlight. I'm guessing that even in the cold it could still get hot if there was sunlight. I'm also thinking that the fans might be better positioned to circulate the flow rather than expel it too quickly so that the air is super heated to get a much higher temp to heat the air ( or dry clothes) quicker. Anyway Ive got my poly sheet and a can of paint so I'll start in the next few days and see what happens. Have you thought about using this sort of passive heater for indoor use? Regards, Brett. |
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| SURFFOILS Newbie Joined: 01/07/2014 Location: AustraliaPosts: 2 |
Here's the poly sheet painted black. My idea is that if the temperature gets quite high then it should be able to dry a larger volume so I'm making mine about 9 -12 inches deep to hold two layers of clothing. 
My cunning plan is to test the system without a fan and see if the heated air will circulate enough on its own to dry the clothes... Hopefully the hot air will rise up inside the front poly wall and then descend down the back so it circulates around the front and back of the box and clothes. I hope to have a system with no moving parts. Failing that, I will use a very low volume fan to slowly circulate the heated air around inside the box, I'm guessing that there's no benefit in heating the air and then removing it too quickly, so if the heated air goes around a few times it should get hotter and more effective as it goes around. Failing that, I'll just follow MacGyvers design if that OK with him ? |
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