I want to build a solar only Fan.

[Kameljoe21]

So I have an extra 100w 18v solar panel and want to build a solar only fan for day time summer use.
I intend to buy a 14 inch Radiator Fan that is rated at 90w and 12v.
I also will get a DC Speed Controller with Reversible Switch rated at 6A DC 10V-60V
My question is should I just run this direct or add in a cheap solar controller ( one that I have CMTD 2420 ) and a Capacitor?
I am just looking for something to buffer the load.
I have a few still good 12v 6 ah batteries, Yet if it dies will it still keep working as it should?
I do have a bad 12v 6ah battery, If I were to hook this up, where should I run the load off the battery or off the charge controller?

 

[tictag]

A solar charge controller's only purpose is to safely charge batteries. If you want this fan to just run during the day AND it can handle a higher than normal voltage (i.e. 18V)* then just connect one to the other. KISS: you don't need a SCC for this application. Obviously, if you get some cloud cover, the fan will slow down or stop.

If you want the fan to run regardless of the eb and flo of solar irradiance, adding a battery and SCC would work ... in that case you'll connect both the fan and SCC to the battery. The fan will drain the battery, the SCC will charge it if the sun is out.

Remember that a 100W panel only actually produces 100W is ideal circumstances (aka STC or 1,000W/m² at 25℃) you can visualise this as a bright sunny day, on the equator, with the panel exactly perpendicular to the sun. All I'm saying is don't expect too much from your panel.


*tbh, the voltage of the PV panel will drop under load anyway.

 

[Kameljoe21]

A solar charge controller's only purpose is to safely charge batteries. If you want this fan to just run during the day AND it can handle a higher than normal voltage (i.e. 18V)* then just connect one to the other. KISS: you don't need a SCC for this application. Obviously, if you get some cloud cover, the fan will slow down or stop.

If you want the fan to run regardless of the eb and flo of solar irradiance, adding a battery and SCC would work ... in that case you'll connect both the fan and SCC to the battery. The fan will drain the battery, the SCC will charge it if the sun is out.

Remember that a 100W panel only actually produces 100W is ideal circumstances (aka STC or 1,000W/m² at 25℃) you can visualise this as a bright sunny day, on the equator, with the panel exactly perpendicular to the sun. All I'm saying is don't expect too much from your panel.


*tbh, the voltage of the PV panel will drop under load anyway.

I do think I will buy that speed controller and see if it does work in the way I think it will, Not all the time will I want or need full power of the rad fan.
If it does not work then oh well. I kinda want this so that I can either reverse the fan or slow it down.
I will keep my eye out for a cheap agm battery and maybe set it up that way.
I am pretty sure the rad fan I pick has a pretty wide range of voltage and with the solar panel open voltage it should indeed drop down to working range.
As per the panel I doubt very much If I will get 90 watts out of even during full sun. We shall see, I do intend on buying a new amp meter, Now that will out that video up.

 

[jasonhc73]

Lookup "Solar Attic Fan".

Amazon.com : GBGS Solar Powered Exhaust Fan AC Power Backup, Built-in Thermostat Switch, 1750CFM, 4200sq/ft Ventilation, IP68 Brushless DC Motor, Adjustable Solar Panel, 40db, 47.5ft Cable, Double Rust Free : Garden & Outdoor

Amazon.com : GBGS Solar Powered Exhaust Fan AC Power Backup, Built-in Thermostat Switch, 1750CFM, 4200sq/ft Ventilation, IP68 Brushless DC Motor, Adjustable Solar Panel, 40db, 47.5ft Cable, Double Rust Free : Garden & Outdoor

www.amazon.com

Or this kind of solar vent fan, it has a "IN/OFF/OUT" switch.

SOLATEK Solar Ventilation Fan without Battery for Boat, Yacht, Camper, Home, White - - Amazon.com

SOLATEK Solar Ventilation Fan without Battery for Boat, Yacht, Camper, Home, White - - Amazon.com

www.amazon.com

 

[tictag]

I'd just buy a ton of those cheap brush-less computer fans and fit them inside a DIY frame. If you get the ones that have a PWM signal input you could also control the speed. You can get them for about £2 - £3 each here in the UK. Cheap'n'cheerful.

 

[Kameljoe21]

Lookup "Solar Attic Fan".

Amazon.com : GBGS Solar Powered Exhaust Fan AC Power Backup, Built-in Thermostat Switch, 1750CFM, 4200sq/ft Ventilation, IP68 Brushless DC Motor, Adjustable Solar Panel, 40db, 47.5ft Cable, Double Rust Free : Garden & Outdoor

Amazon.com : GBGS Solar Powered Exhaust Fan AC Power Backup, Built-in Thermostat Switch, 1750CFM, 4200sq/ft Ventilation, IP68 Brushless DC Motor, Adjustable Solar Panel, 40db, 47.5ft Cable, Double Rust Free : Garden & Outdoor

www.amazon.com

Or this kind of solar vent fan, it has a "IN/OFF/OUT" switch.

SOLATEK Solar Ventilation Fan without Battery for Boat, Yacht, Camper, Home, White - - Amazon.com

SOLATEK Solar Ventilation Fan without Battery for Boat, Yacht, Camper, Home, White - - Amazon.com

www.amazon.com

As much as these unit look nice, the first one looks pretty weak for 60 bucks..
The 2nd one is what I am going to do at a fraction of the price. That unit is 300 dollars.

Where I can buy a 100 watt panel for 70 bucks, rad fan for 20 and a switch 5 bucks. I am going to try the speed controller for 10 bucks. As this controller i found is all manual and may do the trick.
Though I wish I could find one with a higher amp rating rather than 6amps.

 

[Kameljoe21]

I'd just buy a ton of those cheap brush-less computer fans and fit them inside a DIY frame. If you get the ones that have a PWM signal input you could also control the speed. You can get them for about £2 - £3 each here in the UK. Cheap'n'cheerful.

Radiator fans will be more cost effective. Yet I have seen computer fans used in a large number of projects.

 

[Craig]

https://www.amazon.com/Automatic-Co...lt+buck+converter&qid=1583735840&sr=8-13&th=1

Try one of these from the panel

 

[efficientPV]

I picked up a new one of those car fans at a flea market. Quite surprised how inefficient they are and noisy. A speed control is needed to get the speed down. That fan now is in a storage bin as I can find nothing useful to do with it. I have made wood assemblies and mounted a number of computer fans in each assembly for a nice fan while sleeping.

 

[jasonhc73]

View attachment 8784

I think this is the best way to go.
It's just a rheostat and a 2-way switch.

Especially since it's already in a nice pretty panel with fancy silkscreen graphics.

 

[SolarMuppet]

Using a capacitor on the panel and slow PWM frequency can work well. The ’slow’ bit is important as it enables the capacitor to charge in situations where there isn’t enough solar to drive the fan full speed and then be discharged into the fan where the full panel voltage on the capacitor will ‘kick’ the fan round and enable very slow speeds without stalling. If connected direct in low light the fan motor pulls the panel voltage down, which drops the current and there isn’t enough power to turn the motor at all. This can be improved even more with a bit of electronics that only triggers a motor pulse once the capacitor reaches a certain voltage. This then makes it self regulating and the fan will start turning at very low light levels and will be able to turn incredibly slowly But will speed up as more light becomes available. Without this the fan may only start in Strong sun. A diode up from negative improves it further by effectively using the motor’s inductance when the pulse goes off to pull more power up from negative, this also protects the switching transistor.

 

[Sunny Days]

Ive been running the same fan directly from a 100w panel and it spins like crazy!
so i added a buck converter, like the one linked and it runs slower, BUT still to fast!!!

So buy the variable converter so you can select the speed you like, also thee fans at full speed are noisy.
BEEN RUNNING FOR A YEAR...

 

[bulrush]

At 90w 12vdc your fan is running at 7.5amps. It might be wise to get a speed controller that handles those higher amps.

 

[txsjedi]

As much as these unit look nice, the first one looks pretty weak for 60 bucks..
The 2nd one is what I am going to do at a fraction of the price. That unit is 300 dollars.

Where I can buy a 100 watt panel for 70 bucks, rad fan for 20 and a switch 5 bucks. I am going to try the speed controller for 10 bucks. As this controller i found is all manual and may do the trick.
Though I wish I could find one with a higher amp rating rather than 6amps.
View attachment 8785View attachment 8784

I got my hqst 100 watt panel on Amazon for around $80 I think. But you have to look and see who will sell it for that much on Amazon. I also bought a 160 watt from an individual for $110 which puts out at 9.6 amp max.

 

[Electric Night]

Just wondering if you in tend to use it as an "attic fan".