Solar Powered Fans

[Chris L]

The panel produces up to 18V under load; the fans are rated at 12v. By running them at a higher voltage, they may rotate faster than designed (and consume more power, assuming the panel can supply ir), reducing the life of the bearings and otherwise be a bad idea as they may not be able to readily get rid of the heat generated as a result (I'm talking about the fan motors heating up, not the heating effect within the greenhouse)! Running motors above their rated voltage is generally not a good idea.

That's why having a battery and a controller is a good idea - to provide power at a more or less constant voltage of 12v whatever the load / sunshine (unless the battery runs flat). It also helps with the fact that motors draw extra current when they start up.

Sounds like the best plan alright to get a regulator.
Surprisingly cheap on the usual sites.

It is wiring it all together that is confusing me.....

[ralphrmartin]

It is wiring it all together that is confusing me.....

The controller should come with a wiring diagram, Usually there are separate terminals on the controller for the panel, battery, and load,
which should be connected up in a specific order, like this one: for example https://www.aliexpress.com/item/1005005348715201.html
Some generic advice can be found here:
https://a1solarstore.com/blog/wiring-so ... ether.html

[Chris L]

It is wiring it all together that is confusing me.....

The controller should come with a wiring diagram, Usually there are separate terminals on the controller for the panel, battery, and load,
which should be connected up in a specific order, like this one: for example https://www.aliexpress.com/item/1005005348715201.html
Some generic advice can be found here:
https://a1solarstore.com/blog/wiring-so ... ether.html

I'll investigate controllers over the weekend.

[Chris in Leeds]

Have you looked at the usb fans ? I know Asda do one at £4 or £5 I think it is

[MatDz]

Have you looked at the usb fans ? I know Asda do one at £4 or £5 I think it is

USB according to specification gives up to 900 mA/5 V, which makes me think the fans wouldn't move a piece of paper with the blow.

[ralphrmartin]

I have 4 mains powered fans in my greenhouse, rated at 190W each. They move about 4 x as much air (4000 cubic metres per hour each) as the previous ones I had rated at 85W each. Airflow does not go up in proportion to the power the fan needs to drive it. Small computer fans may be OK for a small space the size of a computer case, (e.g. a seed tray sized propagator?) but I can't see them making a useful difference to an entire greenhouse. The plants nearest the fan might get some benefit I suppose.