Solar powered computer fan

Marquis
Marquis Registered Users Posts: 7 ✭✭
in Solar Beginners Corner #1

Hi all! 

I am looking to connect a small, 4 pin 12v computer fan directly to a 10w solar panel with alligator clips. Similar to this video https://www.youtube.com/watch?v=GN2kha5x8Nw . I am not sure how to wire a 4 pin fan to a solar panel with alligator clips.

 Can someone help me?

 Thank you for your help!

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Comments

  • mcgivor
    mcgivor Solar Expert Posts: 3,854 ✭✭✭✭✭✭
    #2
    What color are the wires, sounds like a multi speed fan.
    1500W, 6× Schutten 250W Poly panels , Schneider MPPT 60 150 CC, Schneider SW 2524 inverter, 400Ah LFP 24V nominal battery with Battery Bodyguard BMS 
    Second system 1890W  3 × 300W No name brand poly, 3×330 Sunsolar Poly panels, Morningstar TS 60 PWM controller, no name 2000W inverter 400Ah LFP 24V nominal battery with Daly BMS, used for water pumping and day time air conditioning.  
    5Kw Yanmar clone single cylinder air cooled diesel generator for rare emergency charging and welding.
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  • Marquis
    Marquis Registered Users Posts: 7 ✭✭
    #3

    Hi Mcgivor. Thanks for your reply. I'm planning on buying this fan (https://www.arctic.ac/worldwide_en/arctic-f8-pwm.html). From what I gather, the colors will be blue, green, black and yellow.

    Which wires matter? Strip them and connect directly to alligator clips?

    Thanks in advance for your help.

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  • myocardia
    myocardia Solar Expert Posts: 118 ✭✭✭
    #4
    Hi, @Marquis. I have many, many 120mm and 140mm computer fans, along with a few 200mm versions as well, that I use directly with solar panels. Unfortunately, with the brushless fans that are used in computers, if you wire them incorrectly (i.e., backward), they let out their magic smoke, and you get to buy a new one. Luckily for you, a 10 watt solar panel doesn't have enough amperage to burn up a computer fan, the way that a battery does. Make sure to buy fans that have color-coded wires, if at all possible. It will make your life a lot easier. A lot of computer fans these days do not have colored wires, and there is no way to tell which wire is the positive or negative one, unless you research the motherboard connectors, which have the wires in the same place 100% of the time.

    Just so you know, no matter how many wires the fan happens to have, you will only use two of them, the positive and the negative. I would suggest highly against buying a 4-pin PWM fan, though. You want a 3-pin fan, and you will just ignore the yellow wire, which is the wire that reports the fan rpm. I always just cut the yellow wire off as short as possible, since it is 100% useless, when the fan is used outside of a computer case. FYI, I've never bought a 3-pin fan that did not have a red, a black, and a yellow wire. I've also never noticed a 4-pin computer fan that had colored/color-coded wires, for whatever reason. Good luck.
    DoD= depth of discharge= amount removed from that battery   SoC= state of charge= amount remaining in that battery
    So, 0% DoD= 100% SoC, 25% DoD= 75% SoC, 50% DoD= 50% SoC, 75% DoD= 25% SoC, 100% DoD= 0% SoC
    A/C= air conditioning AC= alternating current (what comes from the outlets in your home) DC= direct current (what batteries & solar panels use)
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  • Marquis
    Marquis Registered Users Posts: 7 ✭✭
    #5

    Thanks a million for your response Myocardia! Will buy a 3-pin fan. Strip the wire and connect to alligator clips? Just like that?

    Thanks!

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  • mcgivor
    mcgivor Solar Expert Posts: 3,854 ✭✭✭✭✭✭
    #6
    Or you could buy a 2 wire fan, red + black - no confusion https://www.amazon.com/90mm-25mm-Terminals-Cooling-Computer/dp/B007PPEQI0
    1500W, 6× Schutten 250W Poly panels , Schneider MPPT 60 150 CC, Schneider SW 2524 inverter, 400Ah LFP 24V nominal battery with Battery Bodyguard BMS 
    Second system 1890W  3 × 300W No name brand poly, 3×330 Sunsolar Poly panels, Morningstar TS 60 PWM controller, no name 2000W inverter 400Ah LFP 24V nominal battery with Daly BMS, used for water pumping and day time air conditioning.  
    5Kw Yanmar clone single cylinder air cooled diesel generator for rare emergency charging and welding.
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  • myocardia
    myocardia Solar Expert Posts: 118 ✭✭✭
    #7
    You can add alligator clips if you'd like, but I usually don't. I just use male and female spade connectors. I use a one male and one female per fan, then the opposite on the panel's outputs...so there is absolutely no way to wire them backwards. Here is a complete set of the type of connectors that I use:
    https://www.amazon.com/Ginsco-Insulated-Disconnects-Terminals-Connector/dp/B01FFCVGBE/ref=sr_1_3?ie=UTF8&qid=1507689931&sr=8-3&keywords=spade+connector+kit

    mcgivor said:
    Or you could buy a 2 wire fan, red + black - no confusion https://www.amazon.com/90mm-25mm-Terminals-Cooling-Computer/dp/B007PPEQI0
    That would be great, except that a 90mm fan will make close to twice as much noise, while moving pretty close to half as much air, when compared to a 120mm, or especially a 140mm fan.
    DoD= depth of discharge= amount removed from that battery   SoC= state of charge= amount remaining in that battery
    So, 0% DoD= 100% SoC, 25% DoD= 75% SoC, 50% DoD= 50% SoC, 75% DoD= 25% SoC, 100% DoD= 0% SoC
    A/C= air conditioning AC= alternating current (what comes from the outlets in your home) DC= direct current (what batteries & solar panels use)
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  • Photowhit
    Photowhit Solar Expert Posts: 6,006 ✭✭✭✭✭
    #8


    From;
    http://pinoutguide.com/Motherboard/mb_pwm_fan_pinout.shtml

    Home system 4000 watt (Evergreen) array standing, with 2 Midnite Classic Lites,  Midnite E-panel, Magnum MS4024, Prosine 1800(now backup) and Exeltech 1100(former backup...lol), 660 ah 24v Forklift battery(now 10 years old). Off grid for 20 years (if I include 8 months on a bicycle).
    - Assorted other systems, pieces and to many panels in the closet to not do more projects.
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  • mcgivor
    mcgivor Solar Expert Posts: 3,854 ✭✭✭✭✭✭
    edited October 2017 #9
    myocardia said:
    You can add alligator clips if you'd like, but I usually don't. I just use male and female spade connectors. I use a one male and one female per fan, then the opposite on the panel's outputs...so there is absolutely no way to wire them backwards. Here is a complete set of the type of connectors that I use:
    https://www.amazon.com/Ginsco-Insulated-Disconnects-Terminals-Connector/dp/B01FFCVGBE/ref=sr_1_3?ie=UTF8&qid=1507689931&sr=8-3&keywords=spade+connector+kit

    mcgivor said:
    Or you could buy a 2 wire fan, red + black - no confusion https://www.amazon.com/90mm-25mm-Terminals-Cooling-Computer/dp/B007PPEQI0
    That would be great, except that a 90mm fan will make close to twice as much noise, while moving pretty close to half as much air, when compared to a 120mm, or especially a 140mm fan.
    Just an example, they are available in larger sizes 
    http://www.ebay.com/itm/14cm-Brushless-PC-Computer-CPU-Cooler-Cooling-Fan-140mm-12V-2Pin-140x140x25mm-/271700592946?hash=item3f429e0932:g:X7MAAOSwGotWlKo9

    Edit. Keep an eye on the voltage to the fan, when I first did as you intend I noticed the voltage was too high, 21.5V in full  sun, so I installed  a regulator which keeps it at 12.6V, not sure how long it would have worked at elevated voltage.
    1500W, 6× Schutten 250W Poly panels , Schneider MPPT 60 150 CC, Schneider SW 2524 inverter, 400Ah LFP 24V nominal battery with Battery Bodyguard BMS 
    Second system 1890W  3 × 300W No name brand poly, 3×330 Sunsolar Poly panels, Morningstar TS 60 PWM controller, no name 2000W inverter 400Ah LFP 24V nominal battery with Daly BMS, used for water pumping and day time air conditioning.  
    5Kw Yanmar clone single cylinder air cooled diesel generator for rare emergency charging and welding.
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  • myocardia
    myocardia Solar Expert Posts: 118 ✭✭✭
    #10
    mcgivor said:
    myocardia said:
    You can add alligator clips if you'd like, but I usually don't. I just use male and female spade connectors. I use a one male and one female per fan, then the opposite on the panel's outputs...so there is absolutely no way to wire them backwards. Here is a complete set of the type of connectors that I use:
    https://www.amazon.com/Ginsco-Insulated-Disconnects-Terminals-Connector/dp/B01FFCVGBE/ref=sr_1_3?ie=UTF8&qid=1507689931&sr=8-3&keywords=spade+connector+kit

    mcgivor said:
    Or you could buy a 2 wire fan, red + black - no confusion https://www.amazon.com/90mm-25mm-Terminals-Cooling-Computer/dp/B007PPEQI0
    That would be great, except that a 90mm fan will make close to twice as much noise, while moving pretty close to half as much air, when compared to a 120mm, or especially a 140mm fan.
    Just an example, they are available in larger sizes 
    http://www.ebay.com/itm/14cm-Brushless-PC-Computer-CPU-Cooler-Cooling-Fan-140mm-12V-2Pin-140x140x25mm-/271700592946?hash=item3f429e0932:g:X7MAAOSwGotWlKo9

    Edit. Keep an eye on the voltage to the fan, when I first did as you intend I noticed the voltage was too high, 21.5V in full  sun, so I installed  a regulator which keeps it at 12.6V, not sure how long it would have worked at elevated voltage.
    Great, that 140mm fan would be perfect for him. Also, I knew there was something I was forgetting! @Marquis you'll want to use one of these buck converters, to keep from wearing your fan out too quickly:
    https://www.amazon.com/DROK-Voltage-Regulator-Converter-1-2-36V/dp/B06VWT6CYF/ref=sr_1_4?ie=UTF8&qid=1507709412&sr=8-4&keywords=DROK+buck+converter
    DoD= depth of discharge= amount removed from that battery   SoC= state of charge= amount remaining in that battery
    So, 0% DoD= 100% SoC, 25% DoD= 75% SoC, 50% DoD= 50% SoC, 75% DoD= 25% SoC, 100% DoD= 0% SoC
    A/C= air conditioning AC= alternating current (what comes from the outlets in your home) DC= direct current (what batteries & solar panels use)
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  • Marquis
    Marquis Registered Users Posts: 7 ✭✭
    #11

    Thank you all for your replies. So I could try with spade connectors as you suggest Myocardia. Problem is, I am really not that knowledgeable about electricity. Some solar panels require you to solder cables to them, and that's above my skills. Do you know of a 10w 12v solar panel that would have wires compatible with spade connectors?

    I am sorry if I sound ignorant, but I am really new to this!

    Thanks again



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  • littleharbor2
    littleharbor2 Solar Expert Posts: 2,113 ✭✭✭✭✭
    #12
    Look on Amazon and eBay. Cut off whatever connectors are on them and crimp your own on,  if necessary. 

    2.1 Kw Suntech 175 mono, Classic 200, Trace SW 4024 ( 15 years old  but brand new out of sealed factory box Jan. 2015), Bogart Tri-metric,  460 Ah. 24 volt LiFePo4 battery bank. Plenty of Baja Sea of Cortez sunshine.

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  • Marquis
    Marquis Registered Users Posts: 7 ✭✭
    #13

    Thank you, Littleharbor.

    This is crimping, correct? https://www.youtube.com/watch?v=-WN-lBkjkAc


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  • littleharbor2
    littleharbor2 Solar Expert Posts: 2,113 ✭✭✭✭✭
    edited October 2017 #14
    That's the idea. I don't use the small crimp connectors much. From past experience I've had mixed results with them.  If you have access to cheaper, and better quality crimp connectors use the better ones,  If not crimped well these little guys can fail, or create high resistance connection. In your case, not a big safety issue. Some heat shrink tubing over the connection would help keep out the weather.

    2.1 Kw Suntech 175 mono, Classic 200, Trace SW 4024 ( 15 years old  but brand new out of sealed factory box Jan. 2015), Bogart Tri-metric,  460 Ah. 24 volt LiFePo4 battery bank. Plenty of Baja Sea of Cortez sunshine.

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  • myocardia
    myocardia Solar Expert Posts: 118 ✭✭✭
    edited October 2017 #15

    Marquis said:

    Thank you all for your replies. So I could try with spade connectors as you suggest Myocardia. Problem is, I am really not that knowledgeable about electricity. Some solar panels require you to solder cables to them, and that's above my skills. Do you know of a 10w 12v solar panel that would have wires compatible with spade connectors?

    I am sorry if I sound ignorant, but I am really new to this!

    Thanks again



    Sorry, I wasn't implying that you need to use connectors, @Marquis. I use them so I can use the same panel(s) for different things. I can charge batteries one day, use it for a fan the next, etc. You should just buy a 10 watt solar panel that comes with wires attached, and buy a cheap wire stripper from anywhere you can find one, like WalMart or wherever, and a roll of electrical tape. Strip all of the wires back about ¾ of an inch, twist them together tightly, and tape them well with the electrical tape. Since you only plan on using this panel to power the fan, it doesn't need to be disconnectable at all, especially since both are so small and lightweight.

    edit: As a matter of fact, just buy this buck converter instead, since it comes with the wires attached:
    https://www.amazon.com/DROK-Waterproof-Converter-Adjustable-Transformer/dp/B014IJM6CS/ref=sr_1_4?ie=UTF8&qid=1507796361&sr=8-4&keywords=DROK+DC+to+DC+buck+converter and buy the cheapest, small package of heat shrink tubing you can find, instead of the electrical tape. That way, it will be waterproof, and will make you look like a pro. You can buy small packages of heat shrink at places like Home Depot/Lowes/Walmart for $2-3, at least the last time I checked their prices.
    DoD= depth of discharge= amount removed from that battery   SoC= state of charge= amount remaining in that battery
    So, 0% DoD= 100% SoC, 25% DoD= 75% SoC, 50% DoD= 50% SoC, 75% DoD= 25% SoC, 100% DoD= 0% SoC
    A/C= air conditioning AC= alternating current (what comes from the outlets in your home) DC= direct current (what batteries & solar panels use)
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  • myocardia
    myocardia Solar Expert Posts: 118 ✭✭✭
    edited October 2017 #16
    Okay, one last reply, unless you have other questions about this stuff @Marquis I would highly consider just spending a few extra dollars, and buying a 20 watt solar panel. Here's the reasoning: it will power a 140mm fan pretty much any time of the day, starting at 8:00 am or so, until an hour or two before sunset. A 10 watt solar panel won't have the ability for nearly as many hours per day. Along with that, it and the second buck converter, https://www.amazon.com/DROK-Waterproof-Converter-Adjustable-Transformer/dp/B014IJM6CS/ref=sr_1_4?ie=UTF8&qid=1507796361&sr=8-4&keywords=DROK+DC+to+DC+buck+converter both have enough amperage to be able to power a second 140mm fan, should you ever end up with a girlfriend. :D<3:o

    edit: Also, make sure to bend the wires straight, before heating the heatshrink tubing. If you don't, it not only will not be anywhere near waterproof, it will make you look like a newbie, instead of a pro. I'm sure there are instructions on youtube on how to properly apply heatshrink to make it both waterproof and professional looking. Oh, and good luck!
    DoD= depth of discharge= amount removed from that battery   SoC= state of charge= amount remaining in that battery
    So, 0% DoD= 100% SoC, 25% DoD= 75% SoC, 50% DoD= 50% SoC, 75% DoD= 25% SoC, 100% DoD= 0% SoC
    A/C= air conditioning AC= alternating current (what comes from the outlets in your home) DC= direct current (what batteries & solar panels use)
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  • Citernate
    Citernate Registered Users Posts: 4 ✭
    #17
    This has been a very helpful read. 

    I have couple of questions. Say you wanted to run 2 120mm 12v fans. Could you run both off of the same 20 watt panel and would you need two converters, one for each fan?

    Thank You,
    Nate
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  • BB.
    BB. Super Moderators, Administrators Posts: 33,634 admin
    #18
    Welcome to the forum Citernate,
     
    You need the specifications for the 120mm Fans... There is a pretty wide range of current/power requirement differences between various models (low speed, quiet--Vs high speed, noisy).

    -Bill
    Near San Francisco California: 3.5kWatt Grid Tied Solar power system+small backup genset
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  • Citernate
    Citernate Registered Users Posts: 4 ✭
    #19
    Thank you Bill,

    These are the specifications listed:

    Size:120 x 120 x 25 mm

    Voltage: DC12V

    Power: 2w

    Rotating Speed: 2000 RPM

    Air volume: 61.2 CFM

    Noise: 31.5 dBA

    Air Pressure: 2.3mmH2O

    Power Connector: 4 Pin / Molex.


    Are these what are needed? Or do I need to dig further.


    Thank you again for your help.

    Nate

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  • BB.
    BB. Super Moderators, Administrators Posts: 33,634 admin
    #20
    That is a pretty low power fan (2 Watts)... A 10 Watt panel would probably work fine.

    A larger panel, you get more hours of runtime per day (closer to sunrise and sunset).

    The issue with solar panels is the operating voltage for a "12 volt panel" is around 17.5 volts Vmp (voltage maximum power)... Depending on your fan, it may be too high of voltage (or not). You can always use a diode to drop voltage, a resistor, or possibly a DC to DC converter.

    Another option is to use a 24 volt fan on the "12 volt panel"--Get a "larger fan" but running at lower voltage will spin slower...

    The fan(s) are pretty cheap from EBay or similar--So it may be worth the experiment to see if the 12 volt fan works OK on your "12 volt" solar panel.

    This fan is a 4 wire fan--So make sure that it runs from 12 VDC without needing some special signal on the other two wires (many times, the other 1 or 2 wires are just for monitoring fan operation/RPM).

    Also, many inexpensive fans have bushings... If you want longer life, looking for ball bearing motors--They will last longer.

    -Bill
    Near San Francisco California: 3.5kWatt Grid Tied Solar power system+small backup genset
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  • Citernate
    Citernate Registered Users Posts: 4 ✭
    #21
    Thank you for all your advice, I appreciate it.

    I am planning on running to fans in close enough proximity (about 2 feet apart) that theoretically they could be run of the same panel. My biggest question is, do the solar panels run similar to house wiring. I.E. When I am looking at running something off the same circuit in a house I am looking at the number of amps they will be pulling simultaneously, is this the same for a solar panel?  So a 12v panel could run x fans until the total energy drawn reaches the amp output of the panel.

    I hope that makes sense. I am better at house wiring than I am at electronics. 

    Thank You,
    Nate
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  • BB.
    BB. Super Moderators, Administrators Posts: 33,634 admin
    #22
    Some of the basic math:

    Voltage = Current * Resistance
    Power = Voltage * Current
    Power = Voltage^2 * / Resistance
    Power = Current^2 * Resistance

    Say you have a 20 Watt solar panel with Vmp~17.5 volts...
    Imp=Power/Voltage = 20 Watts / 17.5 volts = 1.14 Amps
    Pmp = 20 Watts
    Imp = 1.14 Amps (short circuit Isc ~ 1.25 * 1.14 amps)
    Vmp = 17.5 volts for "typical 12 volt panel"

    Realistically, the Vmp-hot Under full sun can drop to:

    17.5 volts * 0.80 panel derating = 14 Volts (Vmp falls as panels get hot--Panels are spec'ed at room temperature--Not under full sun for 1/2 hour to preheat first).

    If you have several fans that take 0.2 amps each:
    • 0.2 amps * 12 volts = ~2.4 Watts
    Running from a solar panel... They will produce about 1/2 rated wattage when sun is >60 degrees off panel face (Cos 60 degrees = 0.5 actual energy to panel)...

    So, you would want a panel that is ~2-4+ times larger than needed... For a 20 Watt panel:
    • 1.14 amps * 1/4 derating * 1/0.2 amps per fan = ~1.4 or ~1 fan for 20 Watt panel (moving air towards sunrise/sunset)
    • 1.14 amps * 1/2 derating * 1/0.2 amps per fan = 2.85 ~2-3 fans with 50% derating (run more in the middle of the day)
    Solar panels are actually current sources (From Vmp to Zero volts, more or less you get 1.14 amps)... But if you draw less than maximum available current (over-sized panel) they do look sort of like a "poor" solar battery.

    Note: if you are drawing more current than available (i.e. trying to draw 1.14 amps at 4pm), you can get 1.14 (or probably 1/2 that current) but voltage will be near zero volts... The power equation:
    • Power = V * I = 0.0 volts * 1.14 amps = 0.0 Watts
    0.0 Watts will not drive a fan (or anything)... So you need to draw less than max current from a solar panel at all times of the day (sun in sky) to actually run the fans. At some point, the voltage will collapse (sun set, clouds in sky, etc.)--And you need to ensure the fan(s) will restart rather than just sucking X amps and keeping voltage near zero... And why the larger panels (wattage) makes things a bit more reliable.

    There are other ways of doing solar panels => fans.. But they usually cost more money that just "over-sizing" the panel would cost. And adding more hardware (DC to DC MPPT type switching power converter) means needing to find the "right hardware"--For example, many DC to DC converters may not start quickly/cleanly at sunrise/after clouds past by. Get the "right hardware", and it can work great--But MPPT DC to DC converters are not that common (and cannot always trust specifications for mass market/cheap hardware).

    For example--Looks interesting. Not expensive. Will it work? No idea:

    https://www.amazon.com/KNACRO-Regulator-Converter-Controller-Voltmeter/dp/B06W52DJ4D

    If you need to run a bunch of fans and need reliable starting--This could be an interesting option (solar panel -> converter -> fans).

    This particular one is a "buck" converter... The output voltage always has to be less than the input voltage (i.e., 14+ volts in, 12 volts or less out).

    Let us know what you end up doing and how things work out? It is always interesting to read about our poster's projects (the good and the bad).

    -Bill
    Near San Francisco California: 3.5kWatt Grid Tied Solar power system+small backup genset
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  • Citernate
    Citernate Registered Users Posts: 4 ✭
    #23
    Bill,

    Thank you for all the info provided there. It is very helpful (will probably need to read a time to two more to fully absorb it all (: ).

    My project is running 2 computer fans inside a greenhouse (will also be upping the solar panel size because if being inside there as well, or maybe run the wire up through the top... things to think about), attached to the top of 2 four inch pipes to circulate air under one of the garden beds to keep the ground slightly warmer. 

    With your info I feel like I can give my first try a go now! Thank you, and I will definitely post here how it does. 
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  • BB.
    BB. Super Moderators, Administrators Posts: 33,634 admin
    #24
    You want to mount (a weather proof) panel outside the green house--The Vmp voltage is (mostly) fixed (drops to ~80% if very hot panel)... Imp is proportional to the amount of sunlight hitting the panel. Mounting panels inside a green house will cut the harvest by 1/2 of even much more...

    I certainly do not have a green thumb... But ventilating a green house usually needs a lot of air movement... Just a quick look, one place listed something like 100% air change every 1 minute.

    A 10x10x8 green house would be 800 cuft... And (I guess) an 800 CFM fan... The small fan you are looking at is only 61 CFM... How big is your green house?

    Unless you are going full blown solar, big side and roof venting is suggested (natural airflow).

    There is also the suggestion of using fan(s) to circulate air inside the green house too... And running 24x7(?). Solar+charge controller+Batteries+Fans...

    https://farmandgardendiy.com/do-greenhouses-need-ventilation/

    I have no idea is the above link is correct for your needs...

    I worry that a few "small" fans are not going to do enough for your needs.

    -Bill
    Near San Francisco California: 3.5kWatt Grid Tied Solar power system+small backup genset
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