Looking for information in Direct connect DC fan to solar panel for Greenhouse.

ROTTENROTTEN Registered Users Posts: 41 ✭✭
Hello everyone.

I bought a water pump, DC and a small solar panel to do a direct connect with it... and it didnt run when I connected them.
Panel powers just fine.. but I dont know whats going on... Id imagine that DC solar to DC appliance would work together..

So im coming here to ask exactly what I need to look for spec wise for a solar panel and a DC appliance in order for them to work
directly connected.


What im trying to do is...

Connect an exhaust fan to my greenhouse, having it directly connected to a solar panel.. DC fan.. to X style solar panel.
I wanna do this because well... when the sun is blaring hot on a clear sunny day are the days that the
greenhouse are the hottest... and well directly at the same time is when the solar panel would be producing the most power...

SOOO... of course it wont run when temps are so low, ill have a thermostat connected, but when temps are enough to
turn the fan on... the solar panel power output should depict the amount of flow coming from the fan...? No?



So.. what do i need to look for on the fan in order to make sure that it will work directly with a solar panel?


Ill be looking at getting a 1000cfm fan, which should be something like 100 watts.. MAYBE... might be over kill... but i want
to get some info first before i buy. Ive been reading.. but noone or nothing has been specific or able to help me with my concern.


thanks.


Comments

  • BB.BB. Super Moderators, Administrators Posts: 29,482 admin
    Connecting motors directly to solar panels is a bit of pain... First, solar panels are "current sources" -- They output current in proportion to the amount of sunlight hitting the panel. Solar panels have no "surge current" capability (batteries are "Voltage Sources" and can output a lot of current while holding the voltage stable).

    And motors tend want a lot of current to "start"--And as they come up to speed, the current requirement falls.

    So, the first problem is motor wants lots of current to start, and a solar panel has very little current outside of ~9 am to 3 pm. There are devices called Linear Current Boosters (here is one). Think of an LCB as an energy converter, can take high voltage/low current from the solar array and output low voltage/high current to the motor to help it start.

    Next problem is that the standard DC motor is a brush type (or universal) motor. They work pretty well, but the brushes wear out pretty quickly (perhaps get a few months to a year of operation during the day before brushes need to be replaced).

    Then there is electronic commutation modules. These can drive Permanent Magnet, Stepper, and/or 3 phase motors (solar panel to "black box" to Motor). These are becoming quite popular (no brushes, and can be very efficient motors)--However they are not usually very cheap. And exception are DC computer fans--They can be pretty nice for jobs where you need to move smaller amounts of air.

    So--Lots of reasons why you may be having problems. If you have a 100 Watt 12 VDC motor (brush or computer fan type), you may need a 200-300 Watt panel to get the motor to start (other than middle of day). You could use an LCB--But those are not cheap. And if you use a solar panel, the operating voltage during the middle of the day may be too high for the motor and you could burn it out.

    Tell us a bit more about the motor/fan you want to use (link to device is fine). The brand/model or Vmp/Imp rating of the solar panel. And if you have used a volt meter to measure the voltage to the motor around noon time (panel facing sun, no shading). And that you have the correct polarity (computer fans may not run if hooked up backwards to DC power).

    -Bill
    Near San Francisco California: 3.5kWatt Grid Tied Solar power system+small backup genset
  • ROTTENROTTEN Registered Users Posts: 41 ✭✭
    Thanks Bill for the detail response, really appreciate that.

    Im speaking a lot in generality and am wanting the basic information in order to help myself better understand how things work.


    Money isnt much of an issue, i dont mind spending $300 on ventilation if it, well, does what its intended. Im going for purpose here,
    and am tossing around ideas to better suit my situation.


    Im in the middle of almost building a solar system off grid, and It might not even be worth it to do what im trying to do... but im filled with
    a bunch of gaps on the understand of the working mechanics and concept.


    I believe in, "you get what you pay for", and Im not a guy to buy cheap stuff.



    http://forum.solar-electric.com/forum/solar-electric-power-wind-power-balance-of-system/solar-water-pumping/341525-hello-friends-looking-for-a-kind-soul-to-direct-me-to-proper-literature
    Heres the link to a thread I made regarding the tiny water pump I bought and tiny solar panel in order for me to just do a lil test..
    and that test was merely... seeing if they can be directly connected.

    For the about water pump, I used a multimeter to make sure panel was working and wasnt putting out to much power.
    When connecting to lil pump, I got nothing...no burnt electrical smell.. no operation... nothing... So i just packed it up and put it away
    then started reading a lil more. Still a lil lost on understanding.. I dont want someone to just tell me this or that.. I want to read something..
    or better yet... "i wanna learn" lol I dont wanna just "know this is how it works", i wanna "know WHY is works"
    I feel with this knowledge I will be better equipped mentally.
    http://www.amazon.com/gp/product/B009X6ADCM?psc=1&redirect=true&ref_=oh_aui_search_detailpage
    http://www.amazon.com/gp/product/B00QRHDIPY?psc=1&redirect=true&ref_=oh_aui_search_detailpage


    Let me share a youtube video that sparked my interest with the ventilation.

    https://www.youtube.com/watch?v=O7Mf0ehaq1I


    NOW... those SanAce 120mm fans... are like $50-60 a piece... which kinda have got me thinking??? Are their other larger fans that pull similar power
    but move also similar air for a cheaper price. I know I said $300 i dont mind.. but to get the CFM i require, which is roughly 1200cfm... Id be looking at around
    300-400 for just the fans, still would need to buy a 100-200 dollar solar panel. SOOO... with that being said... I was then thinking that
    it might just be best for me to save that money and put that toward the WHOLE solar system I want to make...seeing as the MPPT(of course id buy that battery controller)
    controller would be around $400-600 itself, but id have a helluva lot more power at my disposal(hahah disposal sounds of such the wrong word to use since solar is
    suppose to be energy saving and GREEN hehe)





    all this is to be off grip and is designed to give power to my garden.
    I have half acre garden with a 10x16 greenhouse in it.
    Within the greenhouse I will have a few water pumps.
    http://www.pondmasterstore.com/home/pm1/page_12/mag_drive_5_500_gph.html?gclid=Cj0KEQjw58ytBRDMg-HVn4LuqasBEiQAhPkhujGeM6UZU0RVU7kGQI_H_yatLhCzbpBzm66K4MvFrMcaAuXw8P8HAQ
    similar to that, nothing will be bigger then that, im about 90% sure of that.
    At most ill have maybe 5-8 of those running... So i can over estimate that I need a battery system and array setup to be able to pull around 1000watts of power
    for most the time. This is includign the fans.

    The fans wont be as continues as the water pumps, as at night time there will be no need for ventilation besides maybe a quick air exchange once during the night
    to bring in fresh air and take down humidity.



    Excuse my typing and words, I have a lot going on in my head and there is a lot I need to do.
    And most importantly Im learning as I go and Im adapting as well. I kind of want this thread to be my zone for information collection and
    where I can keep track of my progress and what not. Keep things in one spot so to speak, regarding solar and electricity specifically.



    I know there are some standards and some solid guidelines for this solar stuff.. but I cant find it easily, and the stuff I do find
    regarding guidelines are just scattered over the internet, not to easy to figure out lol Seems as though its a field that has some
    information withholding happening, go figure :P

    Like I know that you want to have your SOLAR ARRAY and BATTERY BANK in a specific ratio... like SO MUCH solar power is required
    to charge back X amount to the batteries in order to assure safe and proper battery operation, as well as the operation of the system as a whole...
    I just dont know those figures... ill be reading over this site again, starting from top and going through. Taking notes as I go :)

    see with my situation.. its completely opposite of a home... as MOST my power usage will be DURING THE DAY as oppose to DURING THE NIGHT, as
    most homes are and well the average living of a human being... working during day... come home later in the day or at night and then enjoy being home...


    So with the greenhouse/garden... Im under the assumption.. that I need a LARGER then average solar array in relation to my battery bank, in comparison
    to the average HOME solar setup, where, i believe, youll have a large enough solar array to be able to charge the batteries the next day, ready for night use.

    reason I believe I need a larger solar array, is because of the fact that I will have MUCH MORE running during sun up then I will during sun down.
    only water pumps and minor circulation fans will be running, as during the day, all the fans will most likely be running in order to keep the greenhouse effect.

    and with that larger array.. I have this in mind...

    with that array running, isnt it possible to pull the power from the array... throw it through a controller then out an inverter to AC and use it directly...

    OR??? Does the power used ALWAYS come from the battery bank,,, and then the array is just keeping the bank charged at the same time it has a load?

    OR are the MPPT controllers just smart enough to make it all work out how Im envisioning?

    have a large array with a decent sized battery bank mppt controller quality inverter and bingo bango good to gogo?


    I just need to iron out the details lol :)



    I haev around $7000 saved up for this solar system, and it kind of has to be built this year before winter, I got like 3 months till needs to be NEARLY finished, should
    start it in 2 months... give myself a month to build it and iron out the wrinkles.


    (if heating came to mind during reading this, I built a wood burner for heat the greenhouse, so Ill only be using a small wattage fan to move
    that heat)


    again.. SOOO sorry for the wordy post... i talk a lot and I express myself ALOT and more importantly I express myself AS I AM LEARNING and CHANGING.
    I LIke to express the process and my train of thought, as I like to learn others' trains of thought. Get my drift? :)


    Thanks for taking to time to listen to my rambling...











  • BB.BB. Super Moderators, Administrators Posts: 29,482 admin
    ROTTEN wrote: »
    NOW... those SanAce 120mm fans... are like $50-60 a piece... which kinda have got me thinking??? Are their other larger fans that pull similar power
    but move also similar air for a cheaper price. I know I said $300 i dont mind.. but to get the CFM i require, which is roughly 1200cfm... Id be looking at around
    300-400 for just the fans, still would need to buy a 100-200 dollar solar panel. SOOO... with that being said... I was then thinking that
    it might just be best for me to save that money and put that toward the WHOLE solar system I want to make...seeing as the MPPT(of course id buy that battery controller)
    controller would be around $400-600 itself, but id have a helluva lot more power at my disposal(hahah disposal sounds of such the wrong word to use since solar is
    suppose to be energy saving and GREEN hehe)

    The SanAce 120mm fan specs are here:

    http://www.faneol.com/images/upload/file/9WS1212.pdf

    As you can see, these fans are around the 75 to 100 CFM or so. You can get a 24 volt fan and run it from ~12 volts to 27 volts... A Vmp~17 volt panel should be "safe" and give you moderate airflow. These types of fans generally do not have high starting current requirements, and if you get ball bearing type fans, should last a few years.

    To move large amounts of air, you really need to get a large diameter fan. Here is a random DC fan that is 20 inches in diameter.:

    http://www.faneol.com/images/upload/file/9WS1212.pdf

    At 18 volts, it will take around 52 watts and move at least 1,500 CFM. Not cheap (just a quick search to find "something" to talk about here).

    Note that this fan has about a 5,000 hour life at 32 VDC and should last longer at 18 volts--How long, I do not know. But these are probably brushed motors (from their relatively short life).

    This link says these fans are brushed, and the brushes are replaceable:

    http://www.sunshineworks.com/solar-fans-for-greenhouses.htm

    Commutators (where the brushes ride) do eventually get rough and fail (some can be cleaned by turning on a lathe).

    And then you can find brushless fans too:

    http://www.backwoodssolar.com/large-dc-super-fan-20inch-12-24v
    The Super Fan has been tested through a variety of panel and voltage configurations. We recommend three configurations for “small”, “medium”, and “large” applications. “Small”: all 12 volt panels; a 30 watt panel will provide an airflow of about 9 mph (estimated 1600 cuft/min). “Medium”: a 60 watt panel will produce up to 13 mph (estimated 2300 cuft/min). “Large”: a 135 watt panel will hit 17+ mph (estimated 3000 cuft/min) and faster.
    The best thing about our new DC Super Fan is the brushless motor. Motor brush replacements were common on previous fans especially if they were run at high RPM’s. With no brushes the F20-PLUS will outperform other fans. Solve your circulation issue with this solar direct solution! Be aware, the motor has a built-in 5 minute start delay to prevent stress on the motor during extremely low light conditions. If disconnected and re-connected to power, there will be a delay before the blades start spinning again.

    (I do not know anything about websites or products listed--Just links for discussions).
    all this is to be off grip and is designed to give power to my garden.
    I have half acre garden with a 10x16 greenhouse in it.
    Within the greenhouse I will have a few water pumps.
    http://www.pondmasterstore.com/home/...rMcaAuXw8P8HAQ
    similar to that, nothing will be bigger then that, im about 90% sure of that.
    At most ill have maybe 5-8 of those running... So i can over estimate that I need a battery system and array setup to be able to pull around 1000watts of power
    for most the time. This is includign the fans.

    The fans wont be as continues as the water pumps, as at night time there will be no need for ventilation besides maybe a quick air exchange once during the night
    to bring in fresh air and take down humidity.

    If you can avoid batteries--You are much better off. Obviously for night/low light conditions--Batteries or utility power are the only solutions.

    Do you need a few fans to mix the air in the greenhouse too?

    For night ventilation, can you just "open a few windows"?
    Excuse my typing and words, I have a lot going on in my head and there is a lot I need to do.
    And most importantly Im learning as I go and Im adapting as well. I kind of want this thread to be my zone for information collection and
    where I can keep track of my progress and what not. Keep things in one spot so to speak, regarding solar and electricity specifically.

    I know there are some standards and some solid guidelines for this solar stuff.. but I cant find it easily, and the stuff I do find
    regarding guidelines are just scattered over the internet, not to easy to figure out lol Seems as though its a field that has some
    information withholding happening, go figure :P

    Motors/fans/pumps/etc. are pretty much application specific (size, pressure, electrical supply, etc.). It is difficult to make generalizations about them.
    Like I know that you want to have your SOLAR ARRAY and BATTERY BANK in a specific ratio... like SO MUCH solar power is required
    to charge back X amount to the batteries in order to assure safe and proper battery operation, as well as the operation of the system as a whole...
    I just dont know those figures... ill be reading over this site again, starting from top and going through. Taking notes as I go :)

    see with my situation.. its completely opposite of a home... as MOST my power usage will be DURING THE DAY as oppose to DURING THE NIGHT, as
    most homes are and well the average living of a human being... working during day... come home later in the day or at night and then enjoy being home...

    Since, at night, you may only need 1 air change every 20 minutes vs 1 air change per minute during the day (mid summer)--A relatively small battery system is probably all that is needed (run fans slower, use relay to run fans at night from battery, and during day from solar panels--At least one fan I saw seemed to be designed to run from solar panels and not from a battery bank--So there can be that issue too).
    So with the greenhouse/garden... Im under the assumption.. that I need a LARGER then average solar array in relation to my battery bank, in comparison
    to the average HOME solar setup, where, i believe, youll have a large enough solar array to be able to charge the batteries the next day, ready for night use.

    If you can run from solar panels during the day and batteries at night--It might make things easier (batteries only charge during day, only discharge at night).

    But, as you can see, selecting the right tool for the job can save you lots of power (large slow turning fans are more efficient than small fast fans).
    reason I believe I need a larger solar array, is because of the fact that I will have MUCH MORE running during sun up then I will during sun down.
    only water pumps and minor circulation fans will be running, as during the day, all the fans will most likely be running in order to keep the greenhouse effect.

    and with that larger array.. I have this in mind...

    with that array running, isnt it possible to pull the power from the array... throw it through a controller then out an inverter to AC and use it directly...

    OR??? Does the power used ALWAYS come from the battery bank,,, and then the array is just keeping the bank charged at the same time it has a load?

    OR are the MPPT controllers just smart enough to make it all work out how Im envisioning?

    have a large array with a decent sized battery bank mppt controller quality inverter and bingo bango good to gogo?

    During the day, the solar array supplies both current to recharge the battery bank and run the loads. For a 12 volt system, if the voltage is >13.6, the battery is charging. If the voltage <12.7 volts, the bank is discharging.

    So, the solar array has to be large enough to both charge the battery bank (5% to 13% rate of charge, 10% or larger recommended) and supply power for the loads too (i.e, 9am to 3pm sun).

    Many times, I like to suggest using an AC inverter--Roughly, they are 85% efficient or so--So the minor losses can be made up by using a 20% large solar array (not that much extra array).

    However, you really need to look at the devices being powered. Many of the Energy Star rated appliances are getting almost as efficient as the dedicated DC versions (i.e., refrigerators).

    However, pumps, fans, and motors--The AC versions tend to use more power than the DC versions (and move more water/air too.).
    I just need to iron out the details lol :)

    I am not sure that one can pick a design type (AC or DC powered pumps/fans) and say that will be optimum for the use. At the vary least, I suggest doing several paper designs (pick the equipment, research any special electrical needs) and cost them out.
    I haev around $7000 saved up for this solar system, and it kind of has to be built this year before winter, I got like 3 months till needs to be NEARLY finished, should
    start it in 2 months... give myself a month to build it and iron out the wrinkles.

    It sounds like you have a reasonable amount of money to work with--But do the paper designs first. From the designs I have tried--Adding batteries to a system make the power side almost 4x more expensive vs non-battery implementation (usually well pumps)--Even given that the DC pumps are several times more expensive. Add that batteries may last 2-5 years (for golf cat type), you have ongoing costs too.

    Good luck!
    -Bill
    Near San Francisco California: 3.5kWatt Grid Tied Solar power system+small backup genset
  • ROTTENROTTEN Registered Users Posts: 41 ✭✭
    awesome!!! Thats the kinda reply I have been looking for forever :) THANK YOU!!!

    Just skimmed it briefly, was just checking for a response real quick. But I'll be back in a few minutes to fully
    digest your response.


    You have no idea how much this helps me my friend :)

    THANK YOU THANK YOU THANK YOU .. and Im being serious... not just pretending because this is the interwebs...
    I dont look at it like that... people are at both ends of keyboard.



    this is exactly what I needed, someone that knows this stuff so that they can ask me questions
    in order for them to better help me or to better direct me on my path.
    I understand set backs are life, and I accept them fully, but if you can limit the amount of set backs, why wouldnt you try? right? :)
  • BB.BB. Super Moderators, Administrators Posts: 29,482 admin
    You are very welcome... And when you are done, let us know how you addressed your needs, how well it is works, and any issues.

    Take care and good luck,
    -Bill
    Near San Francisco California: 3.5kWatt Grid Tied Solar power system+small backup genset
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