Solar Kiln

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Project by WoodLe posted 12-02-2012 03:44 AM 18116 views 54 times favorited 23 comments Add to Favorites Watch

I have been working on this solar kiln off and on all summer. So today I moved it outside the shop and wired up the fans and thermostat. It is pretty much done now and ready to dry lumber. The inspiration came from Virginia Tech’s design which I modified and adapted to my own needs and taste. The walls and floor are totally insulated with fiberglass insulation. The doors have an inch and a half of styrofoam sandwiched between the the siding and the inside sheeting. There is a layer of plastic covering the fiberglass insulation before the inside sheeting was installed. The sheeting is 7/16 osb painted with aluminum fiber roof coat paint and then painted flat exterior black. The roof is poly carbonate sheeting. I’m not sure if they will hold up or not but I am using window box fans for circulation. The 4 fans will pull in cool air from the top vents and will blow across the top of the lumber stack, down the front of the pile, thru the lumber stack and then exit out the bottom row of vents. There will be a tarp baffle installed just under the fans that go down to the lumber stack so that the air can’t go straight down and out the bottom vents without going thru the lumber to be dried. Winter is not the best time to use a solar kiln but I’ll try and see what it can do. At least I will be ready to go in the spring! This is my first experience using a solar kiln but I am pretty optimistic about it. I ran into a guy the other day that has a solar kiln and he had it facing west instead of south (because that is where it fit in front of his shop) and he just had a little solar fan circulating air inside with no circulation to bring in cool air and exhaust hot moist air. He thought it worked pretty good and was drying about 3 batches of wood during the summer. So I figured that if his works that good, mine should work a lot better. Thanks for looking!

-- Wooster, Ohio

23 comments so far

View derosa's profile


1597 posts in 3921 days

#1 posted 12-02-2012 03:51 AM

Looks really good and like it would hold more lumber then I could use in a couple years. I could use one like it that could dry a 100-200bf at a time. Do you have a mill to go with it or just buy a lot of wet lumber?

-- A posse ad esse

View lightweightladylefty's profile


3647 posts in 4798 days

#2 posted 12-02-2012 04:17 AM

Your kiln looks great! We’ve admired Virginia Tech’s design and often thought of making one but we already have a few thousand board feet of air-dried lumber stored and are getting older—running out of time to use it all!

We’d love to hear how it works out for you.


-- “Those who would give up essential Liberty, to purchase a little temporary Safety, deserve neither Liberty nor Safety.” Benjamin Franklin -- Jesus is the ONLY reason for ANY season.

View a1Jim's profile


118162 posts in 4663 days

#3 posted 12-02-2012 04:24 AM

Looks great very nice work.


View EarlS's profile


4457 posts in 3434 days

#4 posted 12-02-2012 04:42 AM

Brilliant idea – not the usual cutting board or table for sure. Let us know how well it works from time to time.

-- Earl "I'm a pessamist - generally that increases the chance that things will turn out better than expected"

View Ken90712's profile


18001 posts in 4275 days

#5 posted 12-02-2012 04:43 AM

Interesting and great job. should serve you well.

-- Ken, "Everyday above ground is a good day!"

View DIYaholic's profile


19921 posts in 3761 days

#6 posted 12-02-2012 05:02 AM

That looks great!!! As a matter of fact, it looks just like the one I WANT to build!

Could you please provide a link to the plans??? PLEASE!!!

Did I mention that it looks GREAT!!!

-- Randy-- I may not be good...but I am slow! If good things come to those who wait.... Why is procrastination a bad thing?

View HalDougherty's profile


1820 posts in 4323 days

#7 posted 12-02-2012 12:16 PM


Just google “Virginia Tech solar kiln” and you’ll find more than you have time to read. Here’s the direct link to the plans.

And the instructions.

You’ll find lots of webpages describing how to build and operate solar kilns. I’m in East Tennessee. The high temperature today will be in the high 60’s and the humidity will be very low. Solar kilns work fine at these conditions. I’ve thought about building another one over my heat pump to supply warm air to help heat my house…


-- Hal, Tennessee

View SirFatty's profile


547 posts in 3298 days

#8 posted 12-02-2012 12:38 PM

It would be even better if the fans were solar powered!

-- Visit my blog at

View jap's profile


1251 posts in 3140 days

#9 posted 12-02-2012 01:24 PM


-- Joel

View DIYaholic's profile


19921 posts in 3761 days

#10 posted 12-02-2012 02:15 PM

Thanks for providing the links!!!

I’m looking forward to seeing both your kiln, filled with future projects & those projects completed.

-- Randy-- I may not be good...but I am slow! If good things come to those who wait.... Why is procrastination a bad thing?

View BadDavid's profile


86 posts in 3118 days

#11 posted 12-02-2012 04:34 PM

Thanks for the post and the link. Looks like a great winter project.

-- BD, where bad wood finds a home. Va

View doordude's profile


1085 posts in 4069 days

#12 posted 12-02-2012 07:56 PM

great idea. at least it’s an controlled inviroment. looks like you can move it around with a forklift also.

View MoshupTrail's profile


304 posts in 3566 days

#13 posted 12-02-2012 09:22 PM

Winter will be a great time to test it! Insulated as you have described it should work well. Did you put a thermostat on your fans? I was planning to build one and had decided to use the thermostat from an attic fan to switch the fans on only when the interior temp exceeded (I forget what temp).
One thing I was puzzled by; why would you force the air down, against it’s natural tendency to rise? I would have had the fans exhausting at the top and pulling cool air in the bottom.
You don’t want to dry too fast as that will encourage checking and you need the moisture carried out.

-- Some problems are best solved with an optimistic approach. Optimism shines a light on alternatives that are otherwise not visible.

View YBNORMAL's profile


47 posts in 3516 days

#14 posted 12-02-2012 10:32 PM

Great Job, You will love having a Kiln!
I built one on a trailer frame 2 years ago, works great. Just one note, those plastic fans won’t survive the drying cycle. Temps in the top will reach 150 degrees plus. and the plastic will droop and melt. You will soon have to get some aluminum attic fans. they work great, just remove the roof flange and use the round blade guard to mount the fans. If you are so inclined they also have solar attic fans, but they are a little pricey for my taste (I am CHEAP!).


View douglbe's profile


374 posts in 5047 days

#15 posted 12-03-2012 04:31 AM

YBNORMAL is right, plastic fans will not hold up, I also use an aluminum attic fan in my solar kiln with a thermostat, which works real well. I have put over 2,000 bd ft of Cherry, White Ash, Basswood, Walnut, and Hard Maple through this kiln and it works great. Checking was virtually non-existent and have found no hard casening. This is a great way to dry wood, takes very little attention, and once you learn when and how much to adjust the vents, the drying goes smoothly. You’re going to love using this thing. Have fun.

-- Doug, Reed City, Michigan

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