Are 24 volt car radiator fans a good option for solar shed ventilation? Sheds tend to get very hot in the summer, and my two sheds are no exception. For the past several years, I’ve been using simple configurations of solar panels connected to fairly powerful DC fans to cool them off.
This video shows a 24v fan being tested on my YouTube channel (Solar Power Edge) blog post continues below…
These projects were quite successful. One thing led to the next – so now there are 3 fan systems installed so far.
I normally use 12 volt fans for solar shed ventilation because they tend to be really cheap and in good supply. But I like to reduce systems to the lowest level of complexity. Hence I take on the challenge of trying to run different appliances straight off of DC PV solar panels without little to no electronics involved. This means connecting the fans straight to the panels with little more than a switch – whenever possible.
But the impedance of 12v DC electric fans are not a good match to normal 12 volt solar panels, which often have a voltage of maximum power around 18 volts. Solar panels need to operate in the “Volts Max Power” range, sometimes abbreviated vMP. A 12 volt fan tends to pull the voltage of the solar panel down out of its most efficient range, so there is less power produced overall. It still works, but what if there was a way to move more air and get more power from the same solar panel?
This is where 24 volt DC radiator fans can come in handy. Unfortunately they often cost several times what their 12 volt counterparts cost. For this reason, I always hesitated to buy them. Their construction appears pretty much the same, I think the pricing is more of a low demand issue. 24 volt systems are not as common as 12 volt.
So I have been testing 24 volt radiator fans on direct DC solar power now. One fan in particular I purchased (sold as Universal Air Conditioner CF 0010MP-24V A/C Condenser Fan) turned out to be a near perfect match to a 50 watt solar panel – drawing 45-48 watts from a 50 watt solar panel with zero electronics or regulation! I figured the combination would be pretty decent – but not this good!
In bright sun, the panel was drawn down to around 17.5-18.0 volts DC. That’s practically the maximum power point for the solar panel I was using. All of this happens with amazingly simple technology and no fancy electronic circuits. Based on my tests so far, there is no doubt that 24 volt fans are considerably more efficient than 12 volt versions directly connected to a 50 watt 12 volt panel (PV-to-Load).
After seeing this 24v radiator fan perform, I have decided to install it in my shed for the summer season. This means the PWM controller and DC converter can also become optional – fantastic.
Ventilating and cooling a shed with solar panels and DC fans is a great way to learn about solar power with minimum investment, plus pick up some useful technology skills along the way. If you are interested in the topic, here are some other articles I have written about it plus links to my YouTube presentations:
See Also: Cooling Your Shed With Solar Power! Ventilation and Concepts
Thanks for reading and have a good day! DD, SPE
Solar Thoughts blog 