Direct Solar Connection - not grid tied

[Brill007]

Hello. I’m new here. I’d like to set up a 200 watt /24 volt panel to power an exhaust fan. I’m looking for recommendations on a panel and a controller to regulate voltage. The fan only operates above a certain temp so I’m fine that the fan will only run during daylight hours. Thanks for directing me to additional reading or the right group forum.

 

[zanydroid]

To help you get more service:

Is a battery OK?

What is the power draw of the fan? What is the voltage range? (Less important) What is the drive/regulation type (DC, BLDC, …) for the motor?

 

[Brill007]

Thanks @sunshine_eggo !

Here are the specs that I have:

24-Volt
power: 190-Watt
voltage: ac 120-Volt / 60 Hz

I don’t think that I really need a battery and wanted to avoid having to deal with one for this set up - that said it’s good to have the option of adding one later later.

Thank you!

 

[zanydroid]

Can you take a photo or data sheet screenshot? Those numbers feel confused to me. Specifically they could come from either the panel or the fan.

And solar direct AC is going to be trickier, I inherently presumed we were talking about low power DC fans.

A 190W fan on direct solar of 200W solar panels (which you’ll never see in ideal conditions) is just not going to work.

 

[Brill007]

Can you take a photo or data sheet screenshot? Those numbers feel confused to me. Specifically they could come from either the panel or the fan.

And solar direct AC is going to be trickier, I inherently presumed we were talking about low power DC fans.

A 190W fan on direct solar of 200W solar panels (which you’ll never see in ideal conditions) is just not going to work.

Good idea. Since I haven’t purchased the fan yet I’ll look for a low power DC fan and report back.

 

[Brill007]

And thanks!!

 

[Hedges]

A brushless DC fan is the way to go.
Trick is finding one that accepts gradually increasing power as the sun rises.

For cooling inverters, I tried a few box fans, some would shut off after briefly trying.
What worked was 24V Pabst fans, fed by a "12V" PV panel, which puts out about 21Voc, 18Vmp.

I also got a 48V fan meant for top of a server rack. I mounted it in a gable vent, and fed it from two of those 12V panels (equivalent to the 24V panel you have.) It moves a lot of air in full sun.

Finding one that works is trial and error. There was a surplus store in my area at the time, so I hooked the fans to their bench supply and gradually turned up the voltage to test.

 

[Q-Dog]

I installed one of the gable mount fans from these guys. Everything you need in one box. Works great.

QuietCool Smart Attic Fans - Gable, Roof & Solar - QuietCool Systems

Attic fans keep your attic safe and your attic cool and ventilated all year long. An attic fan can save you up to 30% on your A/C cooling costs by just

quietcoolsystems.com

 

[Brill007]

I installed one of the gable mount fans from these guys. Everything you need in one box. Works great.

QuietCool Smart Attic Fans - Gable, Roof & Solar - QuietCool Systems

Attic fans keep your attic safe and your attic cool and ventilated all year long. An attic fan can save you up to 30% on your A/C cooling costs by just

quietcoolsystems.com

thanks but WAY too expensive.

 

[Brill007]

A brushless DC fan is the way to go.
Trick is finding one that accepts gradually increasing power as the sun rises.

For cooling inverters, I tried a few box fans, some would shut off after briefly trying.
What worked was 24V Pabst fans, fed by a "12V" PV panel, which puts out about 21Voc, 18Vmp.

I also got a 48V fan meant for top of a server rack. I mounted it in a gable vent, and fed it from two of those 12V panels (equivalent to the 24V panel you have.) It moves a lot of air in full sun.

Finding one that works is trial and error. There was a surplus store in my area at the time, so I hooked the fans to their bench supply and gradually turned up the voltage to test.

thanks @zanydroid and @Hedges ! I found a manufacturer (i'm sure there are many more) that has an extensive selection. https://www.ebmpapst.com/us/en/products/compact-fans/axial-compact-fans.html (check out the filter options on this page) does anyone know what the spec should be for a motor so that it will gradually increase in speed as the sun rises without just shutting off? Perhaps any of them would work so long as there was a controller between the fan and the panel? IDK so asking you all. Also, I was looking at automotive radiator fans - would they be an easy match for this application? Appreciate you helping me think through this.

 

[Hedges]

It was a Papst fan like that which worked for me. Don't know what model, and drive electronics may have changed.
Those things are tiny, don't even list current just voltage, wouldn't use near your 200W.
They give a nominal voltage range, most below your Voc. One says 20 - 58V which could work:

Product Detail

www.ebmpapst.com

Automotive radiator fans would likely work with 12V panel. Might be brush type, should work but eventually wears out. If BLDC, risk is that Voc exceeds its ratings.