Solar System Configuration for Solar Lumber Kiln

[BillBlackett]

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Solar Lumber Kiln

I built a solar lumber kiln last Winter (pictured in my avatar), and have been very successfully drying lumber with it. One of the key aspects to drying wood in this particular solar lumber kiln (I made a smaller version of this design ) is to have a fan that is constantly circulating the warm air when the sun is out. When the sun is not out, you actually want the fan to stop. I currently have an old bathroom exhaust fan, along with a timer and a drop cord going to out it, which works great, but I would like for it to be completely solar. I also have a Harbor Freight Solar Panel kit (Please don't judge!), which I used in conjunction with a cheap cigarette lighter fan that also worked great for about 6 weeks and then the fan died.

Hyundai Radiator Fan

Taking a queue from this guy on how to build a DIY solar exhaust fan I've gone to the junk yard and purchased not one - but two Hyundai Radiator fans.

The one I am looking to put in the Lumber kiln has a starting amp usage of just under 12 and runs at just under 5 amps.

Similar Discussion on This Forum

I've read this thread on Powering Several Fans, which is very similar to what I'm trying to do, only I'm not too concerned about cost as long as I get good equipment for my money.

This is what I'm Considering Purchasing:

What I'm currently considering purchasing are two 120 Watt Solar Panels to give me the 12 starting amps I need, a decent charge controller and a good 12 volt deep cycle Marine battery. I'd also like to make a shop fan using the other fan which uses 15 starting amps and runs at 6 amps.

So Here is My Question to the Forum:

How do I configure my solar system, so that the fan in the lumber kiln is only running when the sun is shining and the panels are generating electricity and also store the excess energy to a battery for the occasional use of the shop fan?

Here's a look at the inside (this has a Ford Radiator fan that I took back due to it using more amps than my meter could read)

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[Logan5]

the panels I see in the background are HF film, 15 watts each. 45 watts total, your fan is 90 watts, Used fans are not preferable. I have powered these fans directly from over sized solar arrays for years. perfect use for an ARC array, fan will come on slow in the morning and run peak around noon to 1pm or so. arrange your array panels, s. east, south, s. west configured 40, 20, 40% You will need to do some testing and some basic math to come up with the size of the 3 solar panels that you will need. this is a good project and a good application for off grid solar w/o batteries. Keep in mind used fans will fail maybe sooner than a new fan, using any motor in this way could have a shortened life. that being said I have found these fans very useful, when noise is not an issue.

[BillBlackett]

This is what I'm Considering Purchasing:

What I'm currently considering purchasing are two 120 Watt Solar Panels to give me the 12 starting amps I need, a decent charge controller and a good 12 volt deep cycle Marine battery. I'd also like to make a shop fan using the other fan which uses 15 starting amps and runs at 6 amps.

So Here is My Question to the Forum:

How do I configure my solar system, so that the fan in the lumber kiln is only running when the sun is shining and the panels are generating electricity and also store the excess energy to a battery for the occasional use of the shop fan?

As the original Poster of this thread, let me add some clarification: I am not planning on re-using any parts of my current Harbor Freight solar panel system. They will continue to provide lighting for my kids play house, and a spare 12 volt battery for whenever I need one. I now know that it wasn't a good deal, but in grand the scheme of things, it got me playing around with solar panel systems.

Also - I've already "Thrown my hat over the wall" with the used Hyundai radiator fans, and will be building a completely new system using them.

Thanks for your replies!

[BillBlackett]

. perfect use for an ARC array, fan will come on slow in the morning and run peak around noon to 1pm or so.

What is an ARC Array?

I've searched it a few times, and can't seem to find an answer as it pertains to using Solar Panels.

[Logan5]

an ARC array in my experience is the use 3 or more even numbered panels and arrange them into a fixed ARC 40% of array facing S. south east, 20% facing south, and 40% facing S. south west. wattages based on 1.4 to 2X the DC load, fan, pump or light. this will give you maximum daytime run w/o batteries. You may also want a humidistat to prevent it running on rainy days when pulling in damp air would not dry the wood.

[bcroe]

an ARC array in my experience is the use 3 or more even numbered panels and arrange them into a fixed ARC 40% of array facing S. south east, 20% facing south, and 40% facing S. south west. wattages based on 1.4 to 2X the DC load, fan, pump or light. this will give you maximum daytime run w/o batteries. You may also want a humidistat to prevent it running on rainy days when pulling in damp air would not dry the wood.

I would think, the best direction for the SSE and SSW panels would depend on the latitude of the system. And of course,
the season has an impact. At this location and time, the sun rises and sets north of an E-W line. Bruce Roe

[Logan5]

that can also work depending on the size of array and motor load, fan may be a bit more variable but could work as well.

[BillBlackett]

So - Rather than purchasing two 120 Watt Panels, I could purchase Three 80 watt panels, align them in an ARC, wire them directly to a Load Limiting device, such as a 15 V Zener Diode, then to the Hyundai fan (as suggested in the other thread), and then the rest would go through the Charge Controller and into a battery.

See my Obviously Grade School markups to a standard solar Panel System design below:

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Would this do the trick?

[BillBlackett]

Double Post!

[BillBlackett]

Latest update - This is as much for my own records as anyone else:

I hooked up the smaller of the two Hyundai fans to an adjustable Power Supply I built some time ago using Jameco kit. The fan cranked up, no problem measuring a steady 2.2 Amps with the Voltage on the Power Supply dialed into approximately 12 Volts.

Then I hooked it up to my 45 Watt Harbor Freight Solar Panels. It wouldn't start the fan, but when I spun it by hand, it could keep it going with my meter reading .85 Amps

Here's a couple pics of my adjustable Power Supply:

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In other news: My quest for a Load Limiting device such as a Zener Diode isn't going so well. The closes I can find is a 50 W version like this one.

I'm also a bit concerned about the heat that any Power Limiting device will give off in this arrangement, and am considering just wiring it up with an inline 10 amp fuse and see what happens.

[Logan5]

that looks like a descent quality voltage regulator. may be a bit overkill, if it will work for this application at all. Either way will be nice to have on hand for other future DC power projects. Keep in mind the Harbor freight panels will never put out 45 watt's, Maybe 30 to 35 under the most ideal conditions.

[bcroe]

In other news: My quest for a Load Limiting device such as a Zener Diode isn't going so well. The closes I can find is a 50 W version like this one.

I'm also a bit concerned about the heat that any Power Limiting device will give off in this arrangement, and am considering just wiring it up with an inline 10 amp fuse and see what happens.

Zener diodes get quite expensive in larger sizes. Better to use a small one to control a few big transistors. DC motors are generally tolerant
of a wide voltage range, maybe you don't need a limiter or can use lower voltage higher current panels. A series limiter might be more
efficient (defaulting to a non limiting short at lower power) for you. Buck switchers are quite cool operating, if they can get started. Bruce Roe