Solar Kiln Roof Angle?

[Daburner87]

I cannot direct my kiln completely South as recommended. Im 30 degrees off.  My property has limitations, and I have to face it 30 degrees towards the west so Im at 210 instead of 180.   My zip code is 11951.  How do I calculate what my roof angle should be at to better accomadate?

[doc henderson]

many just use 45°.  you are northern.  also, if you want to optimize for winter so you get year-round average efficiency, you may tip down a bit.  there is info in the solar kiln handbook by @GeneWengert-WoodDoc .  you could try to put glazing on the east side as well.

Design and Operation of a Solar-Heated Dry Kiln | VCE Publications | Virginia Tech (vt.edu)

[doc henderson]

curious how many acres you have, can you diagram your property?
sounds like ideal in summer is your latitude, and in winter add 10° to that. the sun set lower and ideal is for the rays of the sun to hit perpendicular to the glaze (plastic, glass etc.).  the change in angle towards the south is tough.

[Don P]

As you turn to the ends of the day steeper glass will take more rays in, or rather, will glance fewer off.

[firefighter ontheside]

If I remember correctly, the rule of thumb is to use your latitude.  It looks like you're at 40 deg north latitude.  As Doc said, many just use 45 deg.  That makes for easier math.

[doc henderson]

the ideal is to point at the sun mid day so that you get the most throughout the day.  if you cannot change it, I am not sure that changing the angle of the glazing will help that.  your "straight on" time of the day will be later.  again, you could also use glazing on the east side but it will loose heat during the day.  It will make the most difference if you want to use it during the winter.  there are other solar plans that could fix this but it will be more complex and expensive.  thigs like a series of smaller glazing's facing south, or a separate solar collector connected with ductwork and some have some even have a foam damper that closes off the kiln at night.

[Daburner87]

My property is just half an acre.   I have a 44x14 carport where I dry wood right now, and it gets hot but there is verry little airflow.   I plan to move the entire structure off to a corner and get a slightly better location to put the kiln.   The sun shines good from about 7:45am to 4:30pm.  After that the neighbors trees get in the way, but its really the best option I have.

So I can air dry in the carport, and dry in batches in the kiln.  Thats the plan.

[Don P]

It might not be "ideal", but it'll dry wood. I've been thinking about something with some low hoophose bent tubing I have. Heat and vent.

[rusticretreater]

I am going to differ with the folks here.  I like to take things to the next level.

The first thing to consider is your latitude.  The further north you are, the harder it is to get a good angle for the drying process in the late fall, winter and early spring.

You can find the optimal angles by using an online solar panel angle calculator(there are quite a few).  But you will find the winter angle for New York to be around 16-24 degrees, spring/fall 47 degrees and in the summer 70 degrees!  This is degrees from vertical. Picture a wall or a pole with a hinge at the top.  The bottom edge swings out.  The winter setting keeps the panel pointed low at the horizon which is where the sun is at that time of year.  In the summer, New York is tilted closer to the sun and the 70 degree setting directly faces the high sun.

So while the angle is constantly changing as the earth circles the sun, I would say at each of the equinoxes and solstices, you adjust the angle of the solar collector.   This of course is easier said than done.  I am trying to come up with a workable design that don't cost nuthin.  The rest of the forum members will gladly jump in with ideas to help you spend the money to build a top notch system.

[btulloh]

Well there's ideal and then there's possible and reasonable. Yes, the angle of the collector tilting with the seasons improves the solar gain for sure, but ideal would also call for rotating the whole kiln from east to west to track the sun during the course of the day. There are special tracking mounts for solar panels that make these adjustments automatically, but that's a lot simpler than doing something like that with a fully loaded kiln.  

I say go with 45 degrees and face the kiln in the direction your lot allows and it'll dry lumber, but not as fast as hitting the ideals on angle and tracking. If you want to get adventurous and spend the time and money, then try to incorporate some angle adjustability. The solar oanel sites are a good reference for ideal since it's all about maximizing energy gain for either pv panels or a kiln.  

Do what's possible for you and dry some lumber!  Good luck with your build.  You'll really enjoy the benefits of drying your lumber in a kiln.

[doc henderson]

the big advantage of a solar kiln is keeping it simple and inexpensive.  

[Stephen1]

And after it is built, a small copper nail in your neighbours tree will get rid of those pesky trees, and you can then saw and dry them for your neighbour. Make enough to pay for the solar kiln!

[Ljohnsaw]

To adjust for the time of year, just put floor jacks under the corners. Make the pitch 45 and then use the jacks to adjust? 😉