Solar Kiln, But I have no electric on site.

mooses · July 11, 2012, 08:35:00 PM

I need some help. I want to build a solar kiln on my property, but the closest electric is 3/4 of a mile away, so that is out. I was thinking about using a solar panel to charge a battery and then use an inverter to run the fans. Will this work? I don't want to build it and end up with a shed and a big sky light in it. I only need it to dry 8' lengths and maybe 1000' at a time, just for my own use. Any help would be great. I'm going to be in and out for the next couple of day's so if I don't get to you soon, I will get back to you later.

Misfit · July 11, 2012, 09:18:22 PM

I don't know a lot about solar power, but what about using solar panels, an inverter and storage batteries to run the fans or dehumidifier?
Maybe the "Alternative Methods and Solutions" forum could offer some solutions.

PC-Urban-Sawyer · July 11, 2012, 09:21:29 PM

I seem to recall somebody on here mentioning using solar powered fans on a solar kiln. I'm sure that somebody that knows more than I do will chime in with a good solid answer to your question.

Good Luck!

Herb

Ianab · July 11, 2012, 09:23:15 PM

Probably don't even need the battery and inverter. The fans only need to run when the sun is up. As long as your panels can produce enough power to at least spin the fans in overcast conditions it should work. In full sun the fans should be running at full power, and that's when you need the airflow the most. Cloudy day the kiln wont be as hot, and 1/2 power on fans should be all you need. At night the system goes "off", cools down, doesn't need airflow, and does the humid "re-condition" part of the cycle. Next morning, sun comes up, things start to warm up, fans start spinning again. Repeat until the wood is dry.

Trick will to get efficient 12 volt fans that will run off the solar panels. Might want a simple control circuit that cuts fan power once the voltage gets below a certain level? Prevent low voltage "twilight" power feeding the motor in a stalled condition and maybe overheating it? Power only goes on once the panels are producing 12volts with no load, and cuts out if it drops below 6V maybe?

Ian

mooses · July 11, 2012, 09:31:53 PM

Ianab. So your saying I don't need a battery, just a panel and a 12 volt fan, Like a radiator fan in a car? If so how many fans do you think I would need for a shed the size I would need to do 1000' of 8 footers.

WDH · July 11, 2012, 09:48:05 PM

If you google Virginia Tech Solar Kiln, you will get the info that you need or find a link that will provide it.

Brian_Rhoad · July 11, 2012, 09:58:46 PM

Here is some info on a solar powered kiln.

http://tec.appstate.edu/sites/default/files/HPSolarLumberKiln.pdf

Ianab · July 11, 2012, 09:59:58 PM

I don't think you would need a battery. The fans need to come on when the heat source (the sun) arrives. When the sun goes down, things cool off and you no longer need the fans.

Thing about the solar kiln is that nothing about them seems "Critical". You can design for optimal performance, but as long as you have a solar collector that gets warm, and fans that move some air, some vents to get rid of the moisture, then the kiln will "work". The cooler "re-condition" cycle prevents you drying too fast, and as long as you have some heat and air flow you wont dry too slow and get mould.

Probably get away with a couple of small electric car fans. I would get a couple from a junk yard and experiment. See how much power they need, and how they handle lower voltage. Once you know how many amps you will need you can source a panel to drive them, go a bit bigger so you still get air flow in the overcast and build it.

Get those basics right and it will dry wood.

Ian

mooses · July 11, 2012, 10:20:46 PM

BR, Thanks for the link, that just doubles what Ianab was saying. I must of missed that one, I was all over the net searching and couldn't find anything. Thanks for the help, Looks like there will be a build in the near future.

Bill Gaiche · July 11, 2012, 11:15:26 PM

http://solarkilninfo.com/
Try this one also. bg

Bill Gaiche · July 11, 2012, 11:18:25 PM

Here another. http://sbio.vt.edu/about/extension/vtsolar_kiln/

MHineman · July 12, 2012, 01:13:50 AM

Quote from: Ianab on July 11, 2012, 09:59:58 PM
I don't think you would need a battery. The fans need to come on when the heat source (the sun) arrives. When the sun goes down, things cool off and you no longer need the fans.

I think you might be better with a battery since it should keep the voltage from getting too high and damaging the 12V fans.

Of course then you would need some kind control switch to turn the fans on and off. That could be timed, by temp, or by photo eye. I think I'd choose the temp option and have 2 or more temp switches to use the resister pack with the car heater fan to get several fan speeds.

Ianab · July 12, 2012, 02:18:29 AM

QuoteI think you might be better with a battery since it should keep the voltage from getting too high and damaging the 12V fans.

The panels should be regulated to put out no more than about 14V under no load, otherwise they will cook a 12v battery faster than a car fan, that's expecting to run on 13.8v anyway.

A car fan resistor would control the fan speed, but only by wasting watts as heat. If the fans are running a bit more flow than they need to, nothing bad happens. If things are cooler then the slower fan speed doesn't matter.

This is one of the solar fans that VT link to, but it looks pretty pricey.
http://www.greenhome.com/products/appliances/solar_power/fan000001

But I think you could do better with a DIY solution with a bigger panel and automotive fans, even if they were drawing more power. Those ones are only rated at 20watts. You can buy a panel that will produce several hundred watts for less than that set up.

Ian

jdtuttle · July 12, 2012, 06:55:48 AM

This is an interesting topic, thinking about building a solar kiln too. Ian, do you have a schematic of the panel & fan?
jim

jdonovan · July 13, 2012, 07:55:56 AM

Just took the VA tech solar kiln course.

They specifically spent some time on the fans, and fan cycles, and it was mentioned that their design can be built with solar fans. No battery is needed as you really don't need to run the fans at night. BUT you do need a solar controller to feed the right voltage to the fans so you don't destroy them.

You might do as well by sourcing a solar powered attic venting fan. It will have everything you need already put together. Also if you get gable venting fan it will already be setup for a flat wall mount, which will make adaption to a fan plenum a bit easier.

WoodenHead · July 14, 2012, 07:57:39 AM

If you wanted to, solar could work for any kiln including a Nyle L200, but it comes down to cost. It sounds like your requirements are fairly simple, so you may be able to get away with a very reasonable setup. If you are happy with running DC fans only when the sun is shining batteries are not required and in some cases neither is the charge controller. Some DC motors are designed to operate directly from the solar panels (think of solar powered water pumping stations for livestock). Don't limit yourself to 12VDC. Most of the cost effective solar panels work best for 24VDC. A good charge controller can help with that (i.e. higher voltage panel and 12 or 24VDC output).

Something to consider though, is that on cloudy or partially sunny days, your solar panels might not produce enough to power the fans, but your kiln may still get very warm. Batteries add a whole level of complexity and cost. Avoid them if you can. But if you are looking to add a humidifier, the system changes entirely and you will need batteries and an inverter.

I am working on putting together a DH kiln with a Nyle L200. At first I toyed with the idea of powering it with solar (I live off-grid and sell renewable energy products), but the battery requirements are too expensive. It would be even more expensive if I were to power it via a generator ;)

Ianab · July 14, 2012, 03:39:35 PM

QuoteSomething to consider though, is that on cloudy or partially sunny days, your solar panels might not produce enough to power the fans, but your kiln may still get very warm.

That was my thinking too.

I think you need to size the panels so they will provide at least some power to the fans on an overcast day. Because the heat is going to be less the fans don't need to spin at full power. Solar panels still produce power in overcast conditions, just much less than full sun. So even if you can keep 6 volts on the fans, they spin and move some air at least, enough to keep the kiln working at a lower speed anyway.

I would have to experiment with some fans and panels to see what actually worked. Like I said above you can buy ready made solar panel and fan combos where someone has already done the experimenting and got the right mix, so it can be done.

Ian

Bill Gaiche · July 14, 2012, 09:48:41 PM

You can look at this and get some idea of what has been said about the fans. bg
http://www.homedepot.com/webapp/wcs/stores/servlet/ProductDisplay?productId=202913831&storeId=10051&langId=-1&catalogId=10053&MERCH=REC%2d%5f%2dproduct%2d4%2d%5f%2d202913784%2d%5f%2d202913831%2d%5f%2dN

John_Haylow · July 15, 2012, 07:44:25 PM

Quote from: Ianab on July 14, 2012, 03:39:35 PM
QuoteSomething to consider though, is that on cloudy or partially sunny days, your solar panels might not produce enough to power the fans, but your kiln may still get very warm.

That was my thinking too.

I think you need to size the panels so they will provide at least some power to the fans on an overcast day. Because the heat is going to be less the fans don't need to spin at full power. Solar panels still produce power in overcast conditions, just much less than full sun. So even if you can keep 6 volts on the fans, they spin and move some air at least, enough to keep the kiln working at a lower speed anyway.

I would have to experiment with some fans and panels to see what actually worked. Like I said above you can buy ready made solar panel and fan combos where someone has already done the experimenting and got the right mix, so it can be done.

Ian

Hi Ian,
Are you saying that the solar fan combo kits will work okay even on a cloudy day?
John

Hokiemill · July 15, 2012, 09:30:03 PM

It's not cheap, but this is pretty much what I used for my kiln on the solarkilninfo website (http://www.homedepot.com/h_d1/N-5yc1v/R-202913831/h_d2/ProductDisplay?catalogId=10053&langId=-1&keyword=solar+attic+fan&storeId=10051). I used three of them and they're still running just fine after about four years. When the sun is up, and the kiln is collecting heat, the fans turn. No sun, no heat, no need to circulate.

JustinW_NZ · July 16, 2012, 01:51:07 AM

Ive been doing the Solar power direct into 12v fans for ages on Communication sites.
For the kinda opposite resaon, the gear only needs cooling when the suns out, so its like an automatic shutoff when the sun goes away and the voltage isnt there to push the fan (and overcool the gear cabinet).

We just replace the fans every couple of years to make sure but otherwise they go fine, as Ian said, there is some regulation on MOST solar panels (not all).

Im toying with the idea of a solar kiln and i think i would do just this as well.

Cheers
Justin

mooses · July 16, 2012, 04:59:51 PM

Sorry I took so long getting back to reply. I was gone a couple of day's and my computer wouldn't load the forum when I got back. There is alot of great I deas that you all passed along. One thing I should have mentioned, I don't live on my land and I don't get there but once a week because of my work so what ever way I go it must be self sufficient and safe.