Solar Barn! Brand new, need some advise

[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.

[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]

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.

[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)

[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.

[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.

[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.

[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]

Thanks Mike

Assume each fan is 90 watts
180 watts x 12 hours = 2160 watt hours consumed by fan

add 20 % inverter losses brings it to 2592Wh
add 30% battery recharge losses 3370Wh
divide by 5 usable sun hours in a day = 675W harvested per hour

and since solar PV only puts out 80% of nameplate, when in the field and not the lab, you need 850W of PV array


850W of PV @ $2 watt $1700
60A charge controller $500
Pure sine wave inverter (fan motors will overheat and buzz on a mod-sine inverter) $300
Batteries, to hold 7Kw of power (about 2x usage, so you don't discharge below 50%)
single 12V 100ah battery = 1200wh comes up to 6 batteries @ $100 each for the cheap ones. $600

So a little more than $3,000 to run 2 fans. Or buy a long, long extension cord.


Sorry, it's very hard not to laugh, and snicker when someone has been totally misled by the greenies. Whoever told you a 5w panel, you should force them to read this post, and then have them explain what they were smoking. As Sunking said, a 5w panel won't even run a computer fan.

So there goes another 20 minutes.

I appreciate your time. I was able to talk with someone in person yesterday and they went through the formula and told me exactly what they needed to know in order to help me. Thank you for your time. I understand enough to know solar is not my solution. Have a great weekend.

[Russel]

12v fans are the solution.

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.

[Sunking]

Sorry, it's very hard not to laugh, and snicker when someone has been totally misled by the greenies.

Or Obama and voted for him. At least Clinton II (aka Hilary) understands management, budgets, and can control chaotic behavior.

[Sunking]

I'm not sure why I deserved that. I am only trying to find out what I will need to use Solar power to run 2 120V fans for 12 hours. You seemed to work very well with the person before me. What did I say or do wrong in your eyes to not warrant help? So Sorry.

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?

[Mike90250]

I have the same issue but I am only running 2 AC box fans. I understand I will need a constant power source to the battery. I am considering using a solar panel to keep the battery charged. I have been told to use a 5 watt Solar trickle charger panel and another person told me 5 watts is not enough and a trickle charger will not work. After reading this article I am hoping you can tell me what I need to convert DC to AC to run the fans 12 hours a day. The fans are 120V. Thanks you

Assume each fan is 90 watts
180 watts x 12 hours = 2160 watt hours consumed by fan

add 20 % inverter losses brings it to 2592Wh
add 30% battery recharge losses 3370Wh
divide by 5 usable sun hours in a day = 675W harvested per hour

and since solar PV only puts out 80% of nameplate, when in the field and not the lab, you need 850W of PV array


850W of PV @ $2 watt $1700
60A charge controller $500
Pure sine wave inverter (fan motors will overheat and buzz on a mod-sine inverter) $300
Batteries, to hold 7Kw of power (about 2x usage, so you don't discharge below 50%)
single 12V 100ah battery = 1200wh comes up to 6 batteries @ $100 each for the cheap ones. $600

So a little more than $3,000 to run 2 fans. Or buy a long, long extension cord.


Sorry, it's very hard not to laugh, and snicker when someone has been totally misled by the greenies. Whoever told you a 5w panel, you should force them to read this post, and then have them explain what they were smoking. As Sunking said, a 5w panel won't even run a computer fan.

So there goes another 20 minutes.

[kathys]

Second Try

2 box fans? How much power do they consume? How many hours per day will they run? Where are you located?

A 5 watt solar panel will not even run a 5 inch muffin fan to cool your computer for 1 hour.

Power is measured in watt hours. Formula is watts x time (in hours) = watt hours. It works just like money and hourly wages except solar battery power has very high taxes called inefficiency. If you make $5/hour, and work for 5 hours per day you make $25/day but it cost you $2500/day to live; guess what happens to you? Oh yeah the government wants 50% of your income in taxes so you have to make that up too, so you need to make $5000/day to stay afloat but you only make $25/day.

The difference is energy is not like money. You cannot take a loan, use a credit card, or print fake money. You either have it, or do not have it, no exceptions, no mercy. Pure law of physics, no cheating can be done.

I'm not sure why I deserved that. I am only trying to find out what I will need to use Solar power to run 2 120V fans for 12 hours. You seemed to work very well with the person before me. What did I say or do wrong in your eyes to not warrant help? So Sorry.

[Sunking]

I have the same issue but I am only running 2 AC box fans. I understand I will need a constant power source to the battery. I am considering using a solar panel to keep the battery charged. I have been told to use a 5 watt Solar trickle charger panel and another person told me 5 watts is not enough and a trickle charger will not work. After reading this article I am hoping you can tell me what I need to convert DC to AC to run the fans 12 hours a day. The fans are 120V. Thanks you

2 box fans? How much power do they consume? How many hours per day will they run? Where are you located?

A 5 watt solar panel will not even run a 5 inch muffin fan to cool your computer for 1 hour.

Power is measured in watt hours. Formula is watts x time (in hours) = watt hours. It works just like money and hourly wages except solar battery power has very high taxes called inefficiency. If you make $5/hour, and work for 5 hours per day you make $25/day but it cost you $2500/day to live; guess what happens to you? Oh yeah the government wants 50% of your income in taxes so you have to make that up too, so you need to make $5000/day to stay afloat but you only make $25/day.

The difference is energy is not like money. You cannot take a loan, use a credit card, or print fake money. You either have it, or do not have it, no exceptions, no mercy. Pure law of physics, no cheating can be done.