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I have a small solar panel on the roof of my greenhouse that powers a gable ventilation fan. I don't know much about the specs of the panel or fan - I bought them as a unit on eBay. In fact, the only spec listed in the scant information that came with the kit is "27 watts". The panel is approx. 20" x 18". I am changing the ventilation system in my greenhouse and I would like the solar panel to power a small circulation fan inside the greenhouse instead of the gable vent fan. I'm I have no idea what kind of fan will work with my solar panel because I don't know the outputs from the panel. Is there a conversion device that converts the output from the solar panel to 12 volts that would allow my to hook up a standard 12 volt fan? I am really a newbie when it comes to solar but trying to learn.
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Welcome to Solar Panel Talk!
To convert from 12V to 120/220V, you will need to use an inverter. The inverter takes the DC input and converts it into AC, so that you can power standard AC appliances (such as your fan). Unfortunately most inverters will not be able to handle the voltage output from the solar panels. Normally for a solar setup, you will have the solar panels that charge batteries, and from the batteries to your load (or in this case powers the inverters, and from the inverters to the load).
I would recommend that you try find 12V fans to use instead, as that would be the simplest method (as well as costwise). You would then connect the 12V appliances straight to the solar system without having to run through inverters.
To be able to size your solar system correctly, we will need to know; your load (e.g. wattage of the fan, how many fans, etc), for how long you want to run them for, as well as where you are located (for the solar insolation). -
Daz, Thanks for your reply. I am currently running a 12v ventilation fan that I hook up to a car battery. If I understand you correctly, I can directly wire the solar panel leads to this fan. Do solar panels always output 12 volts?Comment
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Forget batteries, use capacitors for small loads like ventilation fans, provided you don't mind the fan switching on and off all day.
Ebay has some cheap supercapacitors (5x 2 Farad for 10 Euros) which will charge faster, with less charging hardware.
Combine them in series to make a 12V 2Farad capacitor, this is the circuit I used to ventilate the shed...DemComment
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Really bad idea placing capacitors in series, in fact completely ignorant and you should not be giving anyone any advice because you have no idea of what you are talking about. When you place two of the 2 Farad capacitors in series you made it a 1 Farad capacitor or you lost 75% of the capacity. If you had bought 12 volt 2 Farad capacotors and placed two of them in parallel, you would have 4 Farads. Your way only got you 1 Farad. You threw your money away and now advising someone else to do the same thing.MSEE, PEComment
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The last two replies completely lost me - the discussion is way over my head! I would be happy to connect my panel directly to a fan and have it run only when the sun shines.Comment
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Hi ther danr43.
Unfortunately, no you cannot wire the fans straight to the solar panels. This is because "12V" solar panels actually have an output of about 18V, which will fry your 12V fans!! The reason for the higher voltage output is because 12V batteries have to be charged at a voltage higher than they already have (or they wont be charged). Hence the 18V output. You have to use a charge controller between the solar panel and the battery. The solar charge controller takes care of the voltage and charging of the battery.
What size 12V ventilation fan(s) are you trying to run?Comment
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It is a small 12" fan mounted on a ceiling rafter. I run it by directly connecting the fan leads to a 12 v car battery. It has 12 VDC, 500 mA on the motor. Made by "O2 Cool".Comment
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No problem. You are getting confused because most of the answers are from people who have no idea what they are talking about.
You can run a fan motor directly from a Solar Panel providing they are a reasonable good match for each other. However you have to know what the fan specs are most notable input voltage and current. We know th evoltage is 12 volts which means the fan will work from 5 to 18 volts. With a DC motor Voltage is directly proportional to RPM's. Lower the voltage, lower the RPM. A 12 volt solar panel operating voltage is 0 to 18 volts. The trick is to have enough current available. In your case th epanel needs to be able to supply at least twice the amount of current the fan needs to operate at full speed.
So if the fan is rated 12 volts @ 1 amp, you would need a 25 watt solar panel. The KEY SPEC is the fan motor. If you bought a kit off Flea Bay, you can be certain you have the cheapest piece of junk money can buy and barely will work.MSEE, PEComment
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I am not sure what your budget is for the conversion, but perhaps you could power it with a solar system?
What would be required would be; 12V battery, 12V charge controller (PWM is fine for small projects like this), and a small solar panel. To determine battery size and the solar panel size, we will need to know for how many hours does the fan operate in a day (eg 8hours, 24 hours, etc).
I think you mentioned something about you already having some parts for a small solar setup? Do you have any parts (solar panel etc)?Comment
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75% of nothing is nothing by my math, you're welcome!DemComment
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