I have been trying to think of a way to use these solar chargers.
You could convert a regular fan to solar if you have the know how. I don't.

Here is a link that might be useful: solar panel battery charger

Cactusfreak, sorry, those are only good for a trickle charge of a 12 volt battery. There are larger panels of course - with much larger prices.

Check this out though, not a squirrel cage but definitely something to look at. It's reversible and up to 1000CFM.

Here is a link that might be useful: Solar Fan Kit

Solar might be a bit too spendy, I would think a 12 or 24v system that ran from the grid when power was available and switched to a battery when it was not would be the most practical, Most of those inflation fans for hoop houses I have seen were rather small. A good sized UPS would probably serve your needs just fine. Your electric company can make electricity cheaper than you can.

Not necessarily, in fact, more than a few people around here make money selling their excess back to the power companies.

That fan was never meant to be used as a squirrel cage anyway. They just got a little of topic and I'm glad. I am goingto look into that fan.

I know one panel was not enough but I was thinking maybe 10. $100 worth and a cheap $10 fan and you could save over $150 if you could rig it up yourself.
For Myself I was thinking of getting it for our SUV and hooking a small fan that I have that goes into the charger(cigarette) port so it will not drain on the battery. We have 2 dogs that love to ride and we usually leave the air on while we run into the store or something. When it's a little cooler we just use the small fan and leave the windows down. I have 2 of those little fans but I'm afraid both of them would drain the battery. If they were connected to the solar panel it would help off-set it.
We have one of the small solar panels (looks very similar to the HF one) and a 12 volt battery (looks like a motorcycle battery) hooked up to our automatic gate opener for when the power goes out. It can open a 500 lb gate 5 times on a charge.

Probably too late to post this info now but....

I have been playing around with inflation blowers and my extensive research has shown that a shop-vac, although spectacular to watch in action is way too big!!!

On the other end of the scale a small 12v PC fan inflates the poly but cannot provide enough pressure to inflate it tight enough.

However, because I was bored I hooked up an old one of these things I found.

http://www.performance-pcs.com/catalog/index.php?main_page=product_info&cPath=145&products_id=1150

It is slow to inflate but once the poly is inflated it maintains a decent pressure. It draws 0.15 amps at 12v.

I have it experementally hooked up to a 17Ah battery so in theory (yeah numbers again!!) If I let the battery go down to 50% capacity it should run for 57 hours.

Hook it up to a truck battery and it should run a month.

If anyone is interested I have pictures but at the moment I can't FTP.

Here is a link that might be useful: The blower I have.

Chris - I knows its been years but how are things working? The links to the fans don't work anymore, can you provide specs? I guess i was wondering how big the greenhouse was, specs on the fan so I can find an equivalent.