converting solar power to DC? can i power fans with this?

[MrDudeMan]

i am doing a project that requires some fans and i figured the easiest way was to use solar power. money is not an issue. i need solar cells that can power probably 6-10 120mm fans...

how can i rig this to be possible? or is it even remotely possible?


thanks


i am searching right now for some answers


edit: the fans will be probably 12v, 6w-10w, 5A to 8A...somewhere around that range...


i have about 16 sq feet of roof space (i am building a dog house)...and i dont think i can use all of it because i need to shingle it and put on some gutters, so basically i have about 10-12sq feet to use (on each side)

 

[ProviaFan]

Solar power, as produced by solar panels, is DC. It isn't AC unless you put a power inverter in the equation to convert the DC to AC. And yes, you should be able to power fans, if the solar panels put out enough electricity to do so. There are two things that I would be concerned about. One is that it might be possible for the solar panels to put out more voltage than the fans could use; in that case you'd need some kind of voltage regularor. The other is that the fans would (obviously) not work as well when the solar panels were in shade or darkness; for that you'd need to set up something where the solar panels charge a battery which runs the fans.

Bear in mind that IANAEE (I Am Not An Electrical Engineer), so take all of the above with many grains of salt.

 

[MrDudeMan]

Originally posted by: jliechty
Solar power, as produced by solar panels, is DC. It isn't AC unless you put a power inverter in the equation to convert the DC to AC. And yes, you should be able to power fans, if the solar panels put out enough electricity to do so. There are two things that I would be concerned about. One is that it might be possible for the solar panels to put out more voltage than the fans could use; in that case you'd need some kind of voltage regularor. The other is that the fans would (obviously) not work as well when the solar panels were in shade or darkness; for that you'd need to set up something where the solar panels charge a battery which runs the fans.

Bear in mind that IANAEE (I Am Not An Electrical Engineer), so take all of the above with many grains of salt.

very good ideas, i just dontknow how to put all of this into use...

i do like your ideas though...

how could they charge up a batter? wouldnt it be more like a capacitor? i also need to put a temp sensor and a timer on the clocks so they only run at 75+ degrees F and only from 8:00AM to 10:00PM

i know this is a lot for right off the bat, but can anyone help me with any section of this in a lot of detail?


thanks

 

[Mday]

let's see, get about a square yard of solar panels, should cost around $100, 1 or 2 fans =D

solar panels are very inefficient, will take forever to recoop any savings...

of course you'll need some cooling to keep the solar panels from overheating...

 

[MrDudeMan]

Originally posted by: Mday
let's see, get about a square yard of solar panels, should cost around $100, 1 or 2 fans =D

solar panels are very inefficient, will take forever to recoop any savings...

of course you'll need some cooling to keep the solar panels from overheating...

from what ive read, they can do way more than 1 or 2 fans for something that size

 

[dejitaru]

One is that it might be possible for the solar panels to put out more voltage than the fans could use

Heh, yeah right.

how could they charge up a batter? wouldnt it be more like a capacitor? i also need to put a temp sensor and a timer on the clocks so they only run at 75+ degrees F and only from 8:00AM to 10:00PM

You could use a thermal resistor



Load
R3 R1
__\/\/\/_________________\/\/\/_____======___
| | | UUUUUU |
| --> _ B1 B2 _ |
| --> ___ ___ |
| | | |
| D1 | R2 | | R3 |
--|>Z---------\/\/\/-----\/\/\/--------------
|
V


B1 - solar cell
B2 - battery or capacitor
R1 - thermal resistor
R2 - resistor
R3 - resistor
R3 - variable resistor
D1 - zener diode


Well, you get the idea. View it in a monospaced typeface.

 

[blahblah99]

You will need to have arrays of solar cells. Lets say for example one square foot of solar cell outputs 1.5V @ 100mA. You will then need to put 8 of those in series to get 12V @ 100mA. You will need 50*(array of 8 cells) to get 12V @ 5A. Of course, in the real world the efficiency of the cells drop as you start putting the them in series and parallel. I don't know the exact output voltage/current of solar cells, but just use that as an example.

Since you are only running it 2 hours out of the day, I would have something like a car battery store the energy produced from the cells. Also, go buy a programmable timer with a relay output so you can turn on/off the power to the fans.

 

[Jeff7]

Decent place for solar panels. It's not the most complete selection, but it is mainly a surplus electronics store. Here is a voltage regulator too.
But you're going to need some efficient fans - as has been said, solar panels are very inefficient yet; based on the specs and size of this solar cell, it is 21.77415 sq cm, and puts out a maximum of 286mW - that's 13.135mW/sq cm. The usual figure given for light is 100mW/sq cm. So assuming all my math is right, which I think it is, that is about a 13% efficiency - probably lower in actual (non-ideal) conditions.

 

[pm]

6-10 120mm fans will be about 20-40W DC. A reasonably priced solar panel that kicks out about 35W will be somewhere in the range of 2.5 ft. by 2.5 ft. and will cost about $175 if you hunt a little. You can get smaller ones that deliver the same power (higher efficiency), but they are more expensive.

40W Panel (6 fans at 6W each)
New: $204 The Alternative Energy Store
Used: ~$150 (Ebay auction that's over)

100W Panel (10 fans at 10W each)
New: $503 The Alternative Energy Store

I would recommend the first link - they have excellent prices on large panels. You will probably be able to power the fans directly if you are careful and choose fans that are rated for up to 20V. But the ideas about charging a battery instead and driving the fan from that are better.

 

[neo4s]

I really like the idea of using solar panels, save the planet, and your electricity bill. Using those emergency car battery charger solar panels may be cheaper, it wont require a voltage regulator. A 40 watt, 12 volt voltage regulator will be expensive. Ive designed and built small circuits that act as a thermostat using a thermistor (and some other stuff) I know theres units you can buy for a house that will monitor the solar panel voltage, battery voltage, power use - and charge the batteries or run the load as needed. That may be overkill for a small application like this. If you use a battery, I hear that you can get good ones from the local telephone company for cheap. It may be a lot easier to just run a power line out there and use a single larger fan. Good luck!

 

[skyking]

There are 12v charging regulators for around 25$, at the solar websites.

 

[MrDudeMan]

Originally posted by: pm
6-10 120mm fans will be about 20-40W DC. A reasonably priced solar panel that kicks out about 35W will be somewhere in the range of 2.5 ft. by 2.5 ft. and will cost about $175 if you hunt a little. You can get smaller ones that deliver the same power (higher efficiency), but they are more expensive.

40W Panel (6 fans at 6W each)
New: $204 The Alternative Energy Store
Used: ~$150 (Ebay auction that's over)

100W Panel (10 fans at 10W each)
New: $503 The Alternative Energy Store

I would recommend the first link - they have excellent prices on large panels. You will probably be able to power the fans directly if you are careful and choose fans that are rated for up to 20V. But the ideas about charging a battery instead and driving the fan from that are better.

thanks for looking all of that up pm.


and thanks to everyone else who has picthed in some information here...i really appreciate it!


i am going to get started on this project very soon, and after i get done looking around online for some stuff, i will let you guys know what i decide to do