Solar Barn! Brand new, need some advise

[kathys]

Thanks Russell

you would be better off just getting "direct" dc fans, still not cheap, but cheaper maybe $130 bucks

http://www.therenewableyou.com/SolarFan_adam@try.com_08_10_02.pdf

describes the process.

his cost for a 20w panel is wayyy too much you can get them here

http://www.sunelec.com/sun-solar-panel-20-watts-1870-vmp-p-843.html

for $55

of if you are going to run two fans just get the 50W panel for about double the price.

You are right. Thanks

[kathys]

It's not possible

because you have supplied no useful information and i am trying to wake you up.

All i know is you have 2 box fans you want to run them 12 hours per day. Energy is very simple grade school math like hourly wages.

Watt hours = watts x hours.
Wages = hourly rate x hours.

So you have a 5 watt panel. I assume you live in outer space where the sun shines 24 hours per day at 100% efficiency which means that 5 watt panel can only generate 5 watts x 24 hour = 120 watt hours.

However for those of us living on earth with real box fans that consume say 100 watts each with 2 of them running 12 hours per day consume 2 units x 100 watts x 12 hours = 2400 watt hours. Since being confined to earth and depending on where we live we only get at best 6 sun hours each day and can only harvest with about 50% efficiency. Tha means we need to harvest 5000 watt hours per day, and with only 6 hours at best in july in phoenix we need at least 5000 wh / 6 hours = a 833 watt solar panel and 250 pounds of battery. If we live any where else other than phoenix or run the fan other than the month of july we will need even a large solar panel of more than 1000 watts.

So without knowing your location and how much power the fans consume all i can do is tell you is 5 watts is fantasy, and try to wake you up to reality.

Ok my bad. Do you want to start over with real information?

no thanks. You would need to be a real human with a real heart and and really what to help. Everyone have to get their jollys somehow.

[Russel]

what is your budget?

you can probably get away with a 2 fan direct system for under $220. is that within your budget, not sure why others have recommend such expensive systems.

[Sunking]

you can probably get away with a 2 fan direct system for under $220. is that within your budget, not sure why others have recommend such expensive systems.

Because she only specified 2 box fans running 12 hours. One has to assume loaction and guess how much power a box fan uses. Box fans can consume anywhere from 75 to 200 watts. That means 1800 to 4800 watt hours per day. No way can you power that with solar for $200, more like $4000 to $18,000.

[russ]

More or less like saying, 'I have 5 gallons of gas. How far can I go'?

Without specifying -
a) the type of vehicle (moped or high powered car
b) the type of driving (city or highway
c) the amount of load/cargo (only one person of 500 lbs)

[Russel]

I could tell that she was hoping for a cheap solution so that is what I suggested. Does it meet her orginal specs, no, but it is the most practical system. obviously no one is going to spend thousands to run a couple of fans, but $200 might work in many places if it is far from the grid. Even 100 feet of outside wire will cost over $100 bucks, plus conduit and labor to bury it!

so solar can be economical for simple things like fans.

[Sunking]

. Even 100 feet of outside wire will cost over $100 bucks, plus conduit and labor to bury it!

so solar can be economical for simple things like fans.

So what? with commercial AC, you have absolutely no practical power limitations or worries about dead batteries and constant replacement. I design mostly battery systems for clients, very large telephone and pipeline companies and always try to find a economical AC solution first. Off grid battery should be th last choice and only option. It is just too expensive otherwise.

[Russel]

your right, she should get AC or use my suggestion of 12V directly coupled fans.
It just depends on how much air she needs moved. A couple of 12V camping fans will cool off a horse fine, but if she needs huge fans to move air throughout a huge barn, than ac is better. the solar solution is actually easier to wire up IMHO.