Soalr Kilns

Andy,

Here is a search with a lot of info…

http://www.google.com/cse?cx=011380079945713262039%3Azls1k4u10qg&ie=UTF-8&q=solar+kiln&sa=Search

I have seen one that CoWood at CSU put together and it worked well. Your biggest challenge is how much you want to invest on humidity and temperature controls.

The USFS-Forest Products Lab in Mad Town will bury you in all the info you could possibly want.

Take care,
Scott

I built a solar kiln 15 years ago when I had a bandsaw mill. We used it to dry red oak and pine boards we cut on the farm. The design was a hybrid based on the Woodmizer model but with a fixed wooden structure loading from the non-collector side. The Woodmizer design contribution was a double poly roof surface at a 45 degree angle facing south. This roof was 20′ in length and covered two 12′ x 16′ bays. The bays had insulated walls and doors, A 16″ fan was installed at the peak of each and operated on a thermostat when the unit came up to heat, On a sunny day temperatures would reach 120 degrees inside. The double plastic roof operated as a dehumidifier and insulated surface. A small blower would pressurize the envelope between the poly and circulate the moist air from the kiln room through this envelope causing the moisture in it to condense on the inner face of the colder outside poly surface and would drain down and out an outside drain. A blue plastic tarp was fastened to the bottom of a baffle coming down from the ceiling which we dropped down and fastened to the top of the load with boards for weight. This forced the air from the circulating fan to go through the stickered pile of boards.

The kiln worked good during the warmer parts of the year and we could dry 1″ red oak boards to 6-8% MC in about 6 weeks with little degrade. Pine was faster. Operation of the kiln was very simple, just load it and shut the doors until the load reached the target MC.The lumber was nice to work with because the heating and night cooling cycles kept degrade and stresses to a minimum. Operating costs were mainly for the fan and it did use quite a bit of electricity. Later when the plastic gave out I replaced it with translucent fiberglass panels without the dehumidifier and used it like that. At one point I had a household dehumidifier hooked up inside which ran on a humidstat.
Later I also toyed with and built a dehumidification kiln using a used Nile unit but never got it running as we sold the mill and abandoned the whole project. The kiln building is now has a metal roof and is used as a carriage shed, donkey barn and as a mounting surface for our photovoltaic solar panels.