Has anyone got any unbiased advice on this ?

alice915

120mm Fan can run in 8volts solar panel?I'm planning to make a DIY solar car ventilation. is 8volts solar panel is good enough to run 120mm cpu fan? i know 120mm power supply at 12v. but can it run under 8volts?

Heater.

It's impossible to answer that question with the information given. 
It takes power to turn the fan at the required speed. Power is measured in Watts. You only give us the Voltage required to drive those Watts into the fan.
Similarly the solar panel produces power, we are only told the voltage of its output.
Now power in watts = amps * volts. So if we knew the current draw of the fan that would tell us the required power. similarly for the solar panel.
We can of course guess:
1) I have no idea but I expect a PC fan consumes between a 100 and 500 mill amps. So perhaps needs upto 6 watts.
2) Without details of your solar panel we cannot know if it can deliver 6 watts at the light levels you have. 
3) Experience tells me 8 volts is not enough to get the fan spinning at a reasonable rate.
4) Similarly I cannot imagine a PC fan can have much effect on a hot car in direct sunshine in the summer time.  

Cluso99

Give it a try. You're not likely to damage the fan.

Heater, you would be surprised what a tiny window opening fan forced will do.

Heater.

Yep, give a try. Nothing beats doing the experiment yourself and learning from experience.
I guess it's effectiveness depends on the PC fan. I've seen some crazy monster turbines on gaming machines.  

Sam_sneak

Running a 12VDC at 8VDC may work, but will reduce the power output by 1/3.

Much depends on how big this solar car is.  Is it a toy or a something a person is sitting in? Ventilation for people is usually in cubic/feet per time unit (sec/min/hours).  Those 120mm fans are for much tighter spaces and more focused air flow over a heat sink or CPU.

Power consumption should give some ballpark indication of scale.  Amps x Volts = Watts.

How many watts is the fan you use for personal comfort rated at?

For cooling people in a solar car, a squirrel cage fan might be more efficient.  Try locating savage units for the best price.  Also, actual air intakes and outlets can be designed to require less need for fans.

MJB

PC fans usually run even at 5 volts.

But they do not like to much heat.
I used some for a solar air heater -
and at around  85°C they died all.

But I think yu will be well below ;-)

So it all depends if your solar panel generates the required current.

Just try - you can not damage anything.

Cluso99

Just try - you can not damage anything.


Well, that's not strictly true even though it's unlikely. If the voltage is insufficient to cause the fan to spin, then it's possible for the windings to overheat and short.