Solar Panels

[Daburner87]

Thinking of building a Virginia Tech style kiln but I know nothing when it comes to solar panels and kits to power the fans inside.  I am thinking of going 16' wide on the build, and running 4 fans.   So what exactly do I need for this kiln to power itself?   

[Kit B]

I used solar fans I found on Amazon. Amtrack is the company name.  I bought 2 of their units which gives you 4 fans and 4 solar panels.  I was a little concerned they wouldn't be powerful enough but when the suns on them they kick up quite a breeze.

[doc henderson]

It is nice that a solar powered fan could auto regulate and have more or less air flow relative to the sun intensity at that time.  off at dark.

[Daburner87]

I used solar fans I found on Amazon. Amtrack is the company name.  I bought 2 of their units which gives you 4 fans and 4 solar panels.  I was a little concerned they wouldn't be powerful enough but when the suns on them they kick up quite a breeze.

Do you have a link to purchase?

[Sod saw]

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Daburner 87,   The 12 volt fans that we use are auto radiator fans.  Each one draws about 80 watts.

In our 18 foot long chamber we have 4 fans.

They are directly driven by 4 solar panels.  Each of those 4 panels are 100 watts.  I have all 4 solar panels wired together (parallel ) into one pair of (20 amp fused) wires to feed the 4 fans (also in parallel).  With each panel and fan in parallel using only one pair oaf wires allows all of the fans to operate fully in the event that one panel is temporally partly shaded.

As a good design rule of thumb, your load should not be above 80 % of the supply.

The fans do slow down some as the day ends, clouds show up, or as the day starts.  They are fully off during the dark hours at night to allow the wood to rest and help prevent case hardening as the temperature will rise above ideal temperatures during those sunny days. 

You can buy kits or you can buy the components from different suppliers.  

I used PVC conduit for the wires but did not fasten it often enough (close together fastenings) and the conduit sagged as the temperatures rose up to almost 160 degrees F. on sunny afternoons.  oops

I have no on/off switch so they have been operating every day that the sun rises.

Good luck with your kiln.

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[Daburner87]

Yea its all the electrical stuff that confuses me.  Did you choose radiator fans because you simply had them or because you knew they could handle the heat and last a long time?  

Ive been looking at harbor freights solar panel that has good reviews.

[Sod saw]

Daburner 87,  I prefer to stay away from harbor freight, my personal choice.  I have purchased the auto fans because they are designed to take the heat of the engine in hot areas of the country and here too.  They seem to last as long as you don't over voltage them.  As me how I know.

They put out a full blast of air with full sun and proper voltage and power available.

I buy mine on ebay.  They came in bundles of two per box.

The solar panels are renogy (check the spelling). from eBay also.   Expect to spend about a dollar per watt these days.   There are other good panel makers too so feel free to shop around.

The fans will run on varying voltage.   As your sun sets the voltage from the solar panels will drop.  in turn the power (available watts) also drops. Remember, according to ohms law, the fan motor resistance stays constant, so as voltage varies so does available power.   The fans slow down.  As the sun rises again the voltage and power available from the solar panel, will rise causing the fans to speed up.  This constant rising and falling of the voltage does not seem to hurt the fan.