I bought mine with 'shipping damage' from U-Bid for less than $500 delivered.

During the heating season, this saves a lot of energy -- about 600 KWH per year in my case -- details here:
http://www.builditsolar.com/References/Half/ProjectsConservation.htm#Dryer

Venting inside not only recovers the dryer heat for house heating, but prevents the dryer from pulling cold air in from the outside to make up for the air its venting outside.

We had a battle with the council, but finally got past them. Our clothes dryer burns gas (propane) rather than using electric elements. Electricity is really only used to run the tumbler motor.

The exhaust gas is vented into one of our glasshouses. The plants love the extra heat, help convert the combustion products (esp CO2), and like the extra moisture. The glasshouse is 5 metres wide, 15 metres long and 4 metres high, so dry clothes, happy plants and less greenhouse gas to deal with.

Back to solar though, different thing!

As long as you have the heat source it will work fine. That's all it's doing is blowing around hot air as it spins so it doesn't matter how the air became hot to begin with, as long as clean air, no smoke etc.. of course.
Dry hot air in, wet hot air out. You might even be able to make a heat exchanger to reclaim the heat in the exhausted air so fresh air is preheated before going into the solar heater also.

The thing I wonder about though, dryers move alot of air, can you heat that much air that fast?
Maybe a couple double walled solar heat stacks, air up through a center pipe, back down between center and outer pipe. Preheats going up center and heats comming down, painted black, maybe behind glass in an insulated box? IF your reclaiming the heat exhausted then the longer it runs and circulates air the hotter it may get once running also.

I think something like that would work here in the mid south, MO. USA, not sure about up north though.

Basically as long as the motor is spinning the drum and blowing air the clothes will dry, just takes longer if the air is not hot and faster if air is hot. Heck clothes dry on the line in the shade in a breeze right :)
Or hanging on the bathroom shower rod they dry also.
 So basically no way it won't work, just a question of how well will it work?
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nothing to lose

Its called a clothesline. Takes some setup time but it is 100% free after.

Not for the lazy or the princess type.

We at least get most of the water out that way then fluff them in the drier a short time.

Not for citified sissies but us hicks been doing it for milennia.

Not as much gadget coolness factor as a powered noisemaker doing it but it will work when all the services disappear.

[/rant]

Uh, convert it to solar and wind put up a clothesline.

How could you guys miss that elephant in the room?

Cheers.

TomW

Ignarus can exsisto rememdium. Sardus est forever

 rough idea but a place to start

Nice thing about buidling/modding your dryers is you can get good ones as scrap for $3-$5 often :)
 I have a nice one I may convert to DC motor if any of the motors I have work for it, then it's just a matter of a timer and a heat source, set it to 30 minutes or 1 hour and forget it.
I am trying to think of a way to use one of those moisture meters like for plant dirt or testing wood for moisture. Might be something better I haven't found yet also.
 Maybe put it to test the moisture in the exhaust somehow, trigger a relay to run/stop the motor? If I figure something out for that then put in wet clothes and start it up, let it run till clothes are dry and auto shutoff :)

I wonder for solar heat, seems everyone wants that heat out of the attic in summer right. What about a ductwork under the roof to suck up the hot attic air, perhaps heat for drying clothes and also help cool the house a bit? You might still need more heat, but that could be a good start for preheat on a hot summer day. Suck the hot air off the attic ceiling and draw in fresh cooler outside air to the attic floor. Maybe run the duct out the wall then through a solar heater outside on the roof or running down the wall on the sun side of the house.

I would try that but I don't have an attic myself.
Of course that's if you have a nice clean attic and good air for the clothes, I have seen very nice attics and some nasty smelly ones also. I would not want the air from the nasty ones in my clothes! Nothing wrong with the nice ones and they got just as hot!
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nothing to lose

By using the current built in wiring such as thermal cut-offs and timers you will be keeping all the built in safety features too.
 Being that this is probably a 220Vac unit one of the lower legs will also be tapped for use for the 120Vac circuits for the timers and required safety items, so if you do try this becareful of those circuits as well.

Winters are another story however. We live in Manitoba (Canada), and winters are pretty cold, windy and nasty. Hanging clothes on the line? Forget it. They will dry in a few days, but mostly they just freeze instantly, turn into a para-sail and are blown away, never to be seen again.

A dryer is a must have item during the winter, but it eats electricity almost as bad as the furnace does. I've tried venting it through various home made filters, but they require constant cleaning, and even then there just seems to be more lint/dust in the house.
The humidity is a problem too, especially if your house is well sealed.
The first time I tried venting the dryer inside the house was a disaster. The laundry room become a steam bath, all the paint bubbled and peeled off the ceiling and walls, swelled the drywall, and even warped the hardwood floors.

That was an expensive lesson which took a long time to repair. If you want to try vent your dryer indoors, make sure you leave the door to the laundry room open, and dry at  a lower heat setting.
You can also build a multi-stage lint trap, and vent it into the cold air return of your forced air heating system, which should also filter that air one more time.

We burn  wood almost exclusively for heat during the winter, and have the furnace fan wired so that it can be turned on to circulate air without the elements lighting up.
This also takes care of the humidity problem when venting indoors, stops the static problem from burning wood, as well as eliminates somewhat that sweltering hot room effect the woodstove creates.

Most electric dryers are 220, the motor/fan assembly is a fairly small unit that runs on 120, the elements are what draws the juice. I haven't tried it (yet) but I think either replacing the element with some DC compatible stuff is possible, and of course a DC motor swap or rewire is doable. It may not heat the air as much with a DC element conversion, but that only means you will have to run it a little longer, which should be a problem if you get the juice for free, right?

When I get my first wind machine up and running, it's definatly on the list of things to do. If there is anything good about freezing cold arctic winters we have here, it is plenty of wind maybe too much for the machines you guys have been building.