The Solar Kiln | why Every Woodworker Should Have One! | Making $$$ and Saving the Planet by HeirloomBuilders
What do you think about Logan suggesting that every woodworker needs a solar kiln? Logan will share with us how a solar kiln works and how it saves him thousands of dollars every year.
Solar Kiln
Logan’s solar kiln was built six years ago. It is a passive energy workhorse and in the past six years, they have dried thousands of board feet of the most beautiful lumber in that kiln for free. This saves a tremendous amount of fossil fuel energy by using the sun to evaporate moisture from the wood.
The solar kiln collects and intensifies heat from the sun to dry lumber. It is basically a greenhouse with fans to circulate the hot air throughout the lumber and remove the moist air as it evaporates. It is a much more efficient process that releases moisture slowly while reducing lumber defects. It may take longer but it yields much higher quality products.
It takes about 400 hours or 1 to 2 months of dry time (25 days in the summer and about two months in the winter).
Quality of Lumber
Lumber coming out of the solar kiln is way higher quality than anything that you’re going to get off the shelf. It dries lumber really well during the day and at night the moisture can be absorbed back to settle the wood and not suddenly split open from any tension.
Cost to Operate and Build a Solar Kiln
You need to prepare almost nothing for almost zero dollars because the sun does all the work for you. It’s super easy. This solar kiln was built from rough-sawn lumber and scrap foam and it cost about $1,500 to build. It literally paid for itself with the first load of lumber.
Design
Insulated polycarbonate roof panels collect the heat from the sun and trap it inside to help the wood dry. This is a calculated roof pitch, it’s a 45 degrees pitch with a 12 and 12 pitch.
To maximize the sun during the winter days it is really important that your roof collection area is 1:10/1 sq foot for every ten board ft of lumber that you’re going to dry. We used rigid foam to insulate the walls and doors of the solar kiln, it goes all the way around to retain heat.
Blue metal panels absorb heat from the sun and radiate it into space better than any other color. It is not energy star rated because it absorbs so much heat, you may not want it in your house, but in a solar kiln, it’s perfect.
Logan also uses a scrap piece of metal to cover the lumber on the top so it doesn’t get a whole lot of direct sunlight to avoid overheating and stress on the lumber on top. The fans are positioned on a baffle wall that hangs down from the peak for structural strength.
They used 7-foot wide doors on strap hinges so they can completely open it up to load a big pack of lumber. To avoid manually stacking and unstacking wood too much it is also advisable to make it 14ft inside to allow you to move around and stack the lumber the way you want.
Drying Lumber
For example, rough sawn red oak cost about $0.70 per board foot when it’s fresh cut green lumber right off the sawmill, but once it’s kiln dried and graded, the market price jumps to $2.80 per board foot which means that that red oak behind me stacked up in this kiln is worth almost $3,000 which is four times what I paid for it.
To save yourself tons of money on your personal woodworking projects this solar kiln right here is the money machine for you. You just need to stack lumber, wait a month and you quadruple your money.
According to a 1992 US Forest Service survey of large scale would kill hires approximately 30 billion board feet of lumber is processed every year and with conventional fuel burning kilns that equates to about two billion gallons of natural gas and petroleum which also releases an insane amount of CO2 and sulfur dioxide into our atmosphere which we don’t need. In fact, we need to be taking it out of our air and we can save every bit of that with the solar kiln drying technology which is exactly why we need a full large-scale transition to solar lumber kiln drying operations
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