So I've finally finished my solar kiln, and as I write, it is in the process of drying a lovely load of local ash.

The build cost somewhere between $1000 - $2000 dollars, all told, and probably took in the neighbourhood of 50 - 100 hours to complete, working nearly exclusively by myself.  If I did it again, it would certainly go quite a bit faster, since I wouldn't have to trouble-shoot as I went along.

The kiln is a smaller, modified design based on this article: http://www.homepower.com/view/?file=HP63_pg50_Scanlin

...but whereas their's can accommodate 16 foot lumber, I built mine with a 12 foot by 8 foot base (3 sheets of plywoood), which provides sufficient capacity to dry just under 1000 board-feet of lumber with a maximum length of 11 ft 2 inches.

The kiln runs on 2 solar (pv) cells which drive an array of 17 small 12-volt fans mounted in a knee-wall on the south side of the kiln.  These draw air through the heat-exchanger (5 layers of black aluminum window screen) which runs in the structure's rafter cavity, and blows the heated air through the lumber stack whenever the sun is shining.  There is no battery storage--when the sun shines, the fans blow.

So far, the HOTTEST temperature I've observed in the kiln was at 4:30pm on September 18th, when it hit a whopping 80.4 CELSIUS (177 degrees F.)!

Of course it cools off every evening, which permits the lumber to 'rest' and allows moisture levels to regulate, which apparently is desireable to prevent case-hardening and other stresses in the wood.

This kiln was born out of high lumber prices and access to a woodlot, which resulted in my purchase of a small bandsaw mill (Woodmizer LT15). From my calculation, the kiln will pay for both itself AND the sawmill before it has finished drying its second load of hardwood! (calculated based on the current price of hardwood like white oak and ash, which I have a significant supply of, even if I restrict myself to windfall.)

Here are some pictures of the finished kiln!  I would be happy to make plans available or discuss the project in more detail, if anyone is interested!

-Tim Engbrecht

Parkland Permaculture