How can I run a RV fan off of a solar panel?

jmcowd
jmcowd Registered Users Posts: 8 ✭
in Solar Beginners Corner #1
I would like to run a 12 v fan (http://www.amazon.com/gp/product/B002N1J5IM?psc=1&redirect=true&ref_=oh_aui_detailpage_o00_s00) off of a solar panel. I am not good at this, but want to learn. Have posted some other questions and you all have been very helpful and thorough in your explanations. This is for our RV travel trailer. There are no wires at this location and I don't want to install any nor damage seals, etc. I would just like to wire this up (if possible) directly to a solar panel. I have researched the fan as much as I can, but the only thing I can find out is that it will draw ~3 amps. Thank you. Julie
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  • lkruper
    lkruper Solar Expert Posts: 115 ✭✭
    #2
    jmcowd wrote: »
    I would like to run a 12 v fan (http://www.amazon.com/gp/product/B002N1J5IM?psc=1&redirect=true&ref_=oh_aui_detailpage_o00_s00) off of a solar panel. I am not good at this, but want to learn. Have posted some other questions and you all have been very helpful and thorough in your explanations. This is for our RV travel trailer. There are no wires at this location and I don't want to install any nor damage seals, etc. I would just like to wire this up (if possible) directly to a solar panel. I have researched the fan as much as I can, but the only thing I can find out is that it will draw ~3 amps. Thank you. Julie

    Some fans can run directly from solar but not all. Would it be a show stopper to add a small charge controller and small battery also?
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  • jmcowd
    jmcowd Registered Users Posts: 8 ✭
    #3
    Maybe not. Everything would be outside on the roof. So then I would need a way to waterproof everything in a box. What do you have in mind? Thank you
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  • lkruper
    lkruper Solar Expert Posts: 115 ✭✭
    #4
    jmcowd wrote: »
    Maybe not. Everything would be outside on the roof. So then I would need a way to waterproof everything in a box. What do you have in mind? Thank you

    If you can calculate how much you will want to run the fan, you can calculate how big the panel and battery would need to be and then see if you can store it on the roof.
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  • BB.
    BB. Super Moderators, Administrators Posts: 33,642 admin
    #5
    Problem is that there are virtually no electrical specifications for this fan. No voltage range, no current/watts listing, etc...

    Solar panels are variable power sources. You could connect a 10 watt solar panels and the fan will spin slowly in the morning/evening, and could sound like an airplane taking off in the middle of the day... Depending on what solar panel you get -- The operating voltage could run from 12 volts to almost 22 volts (of course, at low light levels, the output voltage of the solar panel can drop to near zero volts).

    If you can get a 10 watt panel, it would probably be more than enough for your needs... However, most "standard" solar panels these days are designed to charge a 12 volt battery--And that requires around Vmp~17.5 to 18.6 volts --And would give you a Voc (voltage open circuit) of around 21-22 volts.

    But--Most 12 volts fans are designed to work on ~12 to 14.5 volts--So, running >20 volts (full sun, cold day) could be a "little hot" for the typical fan (if brushed motor, could burn out the brushes in 5,000 hours or less--If electronic commutation motor, could over voltage the electronics).

    There are things that can be done (put a 1/2 dozen of the "right diodes" in series to drop voltage, etc.) if the voltage is too high for the fan.

    And, there is always the question--Is running the fan from 9am to 3pm (and no shading when parked) "good enough" -- Then you can do without batteries. However, if you want the fan to run when the sun is not up--Obviously, a battery is required. And that makes things more complex and expensive to have a reliable unit.

    -Bill
    Near San Francisco California: 3.5kWatt Grid Tied Solar power system+small backup genset
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  • jmcowd
    jmcowd Registered Users Posts: 8 ✭
    #6
    Okay. So lets assume I want a more reliable unit..then I need a 12 watt solar panel, a 12 volt battery and a MPPT controller or will a PVM work?
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  • BB.
    BB. Super Moderators, Administrators Posts: 33,642 admin
    #7
    Lets get back to basics... Do you want the fan to operate more than 9am-3pm? Do you need to run it in the dark? MPPT vs PWM does not matter for the moment.

    Does the Fan you linked to in Amazon meet your airflow/mounting needs (something like 179 CFM--According to one comment I saw).

    And how many hours a day do you need to run the fan?
    • 5 hours per day * 1/2 amp (at 12 volts) = 2.5 AH per day
    • 5 hours per day * 6 watts = 30 WH per day
    • 24 hours per day * 1/2 amp = 12 AH per day
    • 24 hours per day * 6 watts = 144 WH per day
    So--We can see a swing of a factor of almost 5x depending on how I guess about your needs.

    -Bill
    Near San Francisco California: 3.5kWatt Grid Tied Solar power system+small backup genset
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  • Mountain Don
    Mountain Don Solar Expert Posts: 494 ✭✭✭
    #8
    Different question... do you think this fan will do a good job for what you want? I have a Fantastic brand fan in out trailer. On high they state it can move up to 920 CFM on three amps. I can vouch for the 3 amps but all I can say about the CFM is that it does blow a lot of air. Sometimes we want that much air flow when stopping and opening up the trailer which is 100+ F inside. Yes it would require replacement of the vent unit, but that is not that big a deal. But that is just my opinion. I know making modifications, especially holes, to an RV roof conjures up all sorts of potentially bad leak scenarios. That is surmountable though. I have trouble envisioning an external only method of wiring and mounting up a panel, controller and battery that is neat and tidy. Maybe my imagination isn't all that good. :) I'd suggest taking another look at how wiring might be concealed on the inside. There are plastic wire chases that are available that might work for a nice installation.

    The PV panel is a great idea for maintaining charge on an RV and for replacing power used by fans, lights, etc and not needing external power or a generator. Again, only my 2 cents....
    Northern NM, 624 watts PV, The Kid CC, GC-2 batteries @ 24 VDC, Outback VFX3524M
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  • Apples
    Apples Solar Expert Posts: 39 ✭✭
    #9
    Okay. So lets assume I want a more reliable unit..then I need a 12 watt solar panel, a 12 volt battery and a MPPT controller or will a PVM work?

    Basically, yes; that's it. A PWM (pulse-width-modulation) controller. The added battery is your 'buffer', so to speak. You could run your fan from the combination of, say, a 50W (12V nominal) panel, a $30 charge controller and a 50 amp-hour battery... and some 10-gauge copper wire, and of course, the battery would need to be fused near it's positive terminal.
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  • jmcowd
    jmcowd Registered Users Posts: 8 ✭
    #10
    Thank you for all the input.

    Here is the scenario - the bathroom already has a wired fan so I am replacing the small one with the Vortex. The kitchen/dining/living area has a vent with no fan. This is the place I want to install the solar part. I would want to utilize the fan when we are cooking, when the TT is parked and not in use (at our house), and possibly when we are out at a campground when we are plugged in just to keep the inside cooler. We don't dry camp at this point in our adventures. Brand new to this RVing life. My expectation would be that the fan would not be used for more than 5 hours per day. We already have a 125W solar panel charging the ONE battery to keep the other 12V (fan in bathroom and other small 12V accesories) features functioning.

    So, now for more questions:

    what is the difference between your first 2 scenarios BB and which would you recommend and how to do it (or is Apples telling me how to do it?)? :
    • 5 hours per day * 1/2 amp (at 12 volts) = 2.5 AH per day
    • 5 hours per day * 6 watts = 30 WH per day
    what is a 50 amp-hour battery?
    what is a battery that is fused near it's positive terminal?

    Next item; We bought this used with the 125W panel installed and wired to the ONE battery (12V). Is this too much - can the panel charge more battery than that?

    At this time I don't want to try to snake more wires from the existing solar panel to the non wired vent. I know that would be the "simplest and less $$", that is until you pay someone else to do it because neither my husband or myself would tackle that job.

    Thanks again for taking the time to answer all my newbie questions. Maybe someday this will be less confusing.

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  • Zakarume
    Zakarume Solar Expert Posts: 143 ✭✭
    #11
    I just got back from spending a week in my pop up camper i had 2 of theses http://www.amazon.com/Lumitronics-Combination-Incandescent-Extendable-SATISFACTION/dp/B00QU70X7M/ref=sr_1_7?s=automotive&ie=UTF8&qid=1438035840&sr=1-7&keywords=rv+fan. Plugged right into where my 12v lights were at. Used a portable 100 watt solar panel hooked up to the battery. Had no problems
    1460 Watts Solar @24v. 675 AH Battery Bank using 12 6v Trojan T-105. 1 Midnite Classic 150. 1500 Watt 24v Samlex Pure Sine Inverter
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  • PNjunction
    PNjunction Solar Expert Posts: 762 ✭✭✭
    #12
    How about a real RV fan placed inside a box case? Endless Breeze dc fan. by the Fantastic Vent company. I think this is the same one Mountain Don is using.

    Basically it is one of their roof / wall mount RV fan motors put inside a convenient box. 3 positions at approx 1, 2, and 3 amp draw.

    Great motor, plenty of air. The highest level at 3 amps moves so much air that it is really for flushing / clearing - you probably wouldn't be comfortable sitting in front of it.
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  • Apples
    Apples Solar Expert Posts: 39 ✭✭
    #13
    Thank you for all the input.

    Here is the scenario - the bathroom already has a wired fan so I am replacing the small one with the Vortex. The kitchen/dining/living area has a vent with no fan. This is the place I want to install the solar part.

    We already have a 125W solar panel charging the ONE battery to keep the other 12V (fan in bathroom and other small 12V accesories) features functioning.

    You may run your additional fan off of this existing setup.


    what is a 50 amp-hour battery?
    what is a battery that is fused near it's positive terminal?

    With due respect, you're in need of some fundamentals. There should be a Solar FAQs section somewhere. I'm on my way out the door and will be tied up for the next few days. I'm going to defer to the experts, here, like BB.


    Next item; We bought this used with the 125W panel installed and wired to the ONE battery (12V). Is this too much - can the panel charge more battery than that?

    At this time I don't want to try to snake more wires from the existing solar panel to the non wired vent. I know that would be the "simplest and less $$", that is until you pay someone else to do it because neither my husband or myself would tackle that job.

    Thanks again for taking the time to answer all my newbie questions. Maybe someday this will be less confusing.

    One day, it will be!

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