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Solar powered fan i built for the greenhouse

Hi everyone,

Here is my attempt at providing air circulation and stopping the plants from getting cooked in closed spaces. I have roughly a 2 metre long x 1 metre long x 2 metre high greenhouse. I don't like running power outside so I got all the parts and built this solar powered fan. This unit cost me $175.00 AU and can be modified to suit your needs as well as customized. Normally the unit would have cost $300.00 but my parents can get me the parts. I am currently using it in my highland greenhouse.

Here is a simple diagram as I have yet to take photos:

                       BATTERY
                             I I
                             I I
                     REGULATOR
                       I    I     I I
                       I    I     I I
             THERMOSTAT   I I
                       I    I     I I  
                       I    I    SOLAR PANEL              
                        FAN

It does wonders as spring sets in and summer approaches.

Because the green house has no openings for ventilation and is always closed, the thermostat regulates the temperature inside and never exceeds 30 degrees celcius and will turn the fan on when it reaches this temperature (adjust at will) and will constanly expel hot air from inside the greenhouse...outside until the temperature goes below this value and the equilibrium is maintained. It will continue to do this.

The regulator on the other hand regulates the solar panel and the battery so the battery will never overcharge. I am using a 12v solar charge panel that recharges a 12v battery. This is quite a small compact unit and very effective. It does not consume alot of power.

A number of fans can be added for a larger sized greenhouse providing you increase the number of solar panels and batteries so that it does not die on you. It will not stop working but the the ability of the fan may be hindered if you do not provide the appropriate power requirements for the solar panel and batteries. In this case, bigger is better.

The fan and thermostat are positioned at the top where heat is most likely to build up. The thermostat is placed in a position out of direct sunlight but where it can turn on when it reaches 30 degrees celcius. The fan is attached to a tube (ie vacuum tube or ducted heating tubes) and the other end is positioned at the bottom and outside. This is where the heat is expelled.

At the very bottom of the greenhouse I have a resevoir of water that provides the humidity that is lost when the fan expels the hot air. Simple but effective way because the way I see it, if it's warm or hot there is always evaporation as long as there is water to evaporate.

Specifics:

1)The regulator is a Solar Charge controller that has inbuilt discharging and overcharging protection thus protecting the battery and giving it better performance and a very long life. It has inbuilt gasing regulation and this also prevents acid build up layering and in co with a temperature dependant function, the battery capacity is better used, especially when the battery is not operating the fan for long periods.
The gasing regulation switches off the overcharge protection until the so-called final gasing voltage is reached. Also the gasing regulation increases the final charge voltage during high cyclisation.
I use a solar charge controller 5.0 i think. I will have to look at it as there are a few models.

2) The solar panel size I use is 30cm wide by 80cm long. It is small but can generate enough electricity to charge the battery to full before the end of each day with no decrease in charge.

If anyone has questions about specifics please pm me or maybe ideas on expanding on this technology.

Two new projects I am currently working on are:
1) a solar-powered air-coonditioner or swamp cooler, but I'm still debating on which one is more productive.

2) a solar - powered space heater.


Thanks,
Christian
 
Sounds good! I might need to get one of these if\when I get a job as I`m surrently the hi bidder on a 6x6x8 polycarbonate greenhouse with ventilation window on top. I look forward to getting this and putting a small heater into it for the winter set to keep it above freezing and putting my more winter hardy cps out there. This will make room for my Neps in the house. And I could put my neps out for the warmer months!
smile.gif
I plan on useing a small fan driven space heater hooked up to a thermostat would this be good?
 
hi pond boy,

Yes your idea would work. This is the next project that I am currently constructing as well as a 12 volt solar powered airconditioner unit. You would use the same principles as in the solar powered fan but replace the fan with a 12volt heater. You can buy 12 volt heaters but most of them are for use with the car cigarette light plugs but all you have to do is cut the end off and connect the wires appropriately. In regards to the thermostat you will need one that is set to lets say 10-12 degrees celcius and will turn the heater on if it goes below this value. You may need a bigger battery and an appropriate solar panel to recharge if it will be running throughout the cold nights where there is no light. Even if it is running for every second hour in an enclosed space you can prevent your plants from freezing. Sometimes building this can be expensive but if you shop around you can find great bargains and in the long run, inexpensive power bills.

I saw a 12 volt space heater for $30.00 AU here at kmart.

You can even get 12volt air - conditioners or swamp coolers.

cheers,
Christian
 
I won the auction! Actualy ii was just planning on running a power cord out to the greenhouse,of course if power goes out.....
 
Looks pretty ingeniuous, but isn't it a bit...expensive when a good-sized desk fan could pull the same? Of course, they're not as environment-friendly.
 
Hi Sszvein,

You can always run electricity outside, but I built this along the lines of being a portable and light weight unit. And as you mentioned environmentally friendly and better for the plants. It isn't expensive if you consider the long term use of your electricity and your bills. It is new technology and that's why it costs a little bit more.

Christian
 
hi pond boy,

Congratulations on winning the auction.
smile.gif

Sounds like you get power blackouts. That would be bad for the plants on a hot day. If you used a solar powered unit, you can at least guarantee that the fan would be working.

Christian
 
True true, but since I live in Quebec, electricity is cheap; but I guess that with the energy crisis coming, it won't stay so for very long (at least people will be less inclined to waste it as shamefully as we do right now.)
Where did you get your solar panels btw? And what sort of power do they produce?
 
hi Sszvein,

for the solar -powered fan I am using a solar panel usf-5 and for the other projects i am using two usf-32 panels to provide more electricity to recharge the bigger batteries.

In a nutshell, the usf-5 model is sized to maintain and recharge a 12v battery. it provides 13amp-hrs a week.
Eleven solar cells are connected in a series to produce 16.5 volts for 12 volt battery charging and it is quite sufficient. Also if a solar cell was to get damaged, the unit would compensate this and bypass the cell via diode and still produce the same amount of electricity.

In regards to obtaining them, I will have to ask my parents and get back to you on that one. I know I spent alot of time trying to find them and found them at places such as Disk Smith but they were considerably Overpriced!

thanks
Christian

cheers
 
  • #10
Ohhh! Interesting =).
I love thinkering, but I have yet to plunge with solar energy. How much daily sun does those panels require to fill their "quota" in amp?
 
  • #11
Well no only during big storms. Lol. And my big problem would be loseing heat ot haveing too much of it:p
 
  • #12
Hi pondboy,

If you place the solar panel in a sunny place, you don't really need to worry about the panels filling their quota in amps providing you accompany the 12v battery with a 12v solar panel around the size of 30cm wide by 80cm long. The panel will always be receiving light and will be enough to charge the battery.
This is well in the limits of the dimensions as I have mentioned in the above post of my greenhouse. You may have to increase the values, i.e. double the amount of the solar panel and battery if your greenhouse is twice as large as mine.

You will need to secure the solar panel properly. There are light weight versions available.

Also the solar powered fan takes out excessive heat. You will need to create a solar powered space heater if the heat is lost during cold nights. Pm me for details of unit if you like.

Christian
 
  • #13
Are you planning on using a SLA battery?

I'm a battery freak, I fly Electric RC airplanes.
 
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