SOLAR PANEL TO POWER COMPUTER FAN FOR VENTING (initial testing complete)

[bansil]

I have a vent in my project that is about a 4 inch dia hole with a vent cover on it to keep out the rain etc.
It works good now at venting off hot air,I would like more though.

I am thinking of adding a 120mm 12v ball bearing computer fan to the hole and then sticking a 5w or 10w solar panel on the roof that is wired directly.
My thinking is it will slowly start to spin (variable) and then go to full capacity as the sun powers the panel and at night it wont vent(powered) since there is no sun.

Will the fan work at less than rated power availible and then if panel is putting out say 18/19v will this kill the fan.

Here are specs of 2 panels

Will the 5w work?



5 WATT PANEL

PARAMETER-solar panel 　
Related power 5W
Voc 22.41V
Vop 17.9V
Short circuit current (Isc) 0.3A
Working current (Iop) 0.28A
Output Tolerance ±3%
Temperate coefficient of Isc (010+/- 0.01 )%/ ℃
Temperate coefficient of Voc - (0.38 +/-0.01 )%/ ℃
Temperate coefficient of power Voc -0.47%/℃
Temperature range -40℃to +80℃






10 WATT PANEL

Related power 10W
Voc 20.6V
Vop 17.3V
Short circuit current (Isc) 0.69A
Working current (Iop) 0.58A
Output Tolerance ±3%
Temperate coefficient of Isc (010+/- 0.01 )%/ ℃
Temperate coefficient of Voc - (0.38 +/-0.01 )%/ ℃
Temperate coefficient of power Voc -0.47%/℃
Temperature range -40℃to +80℃

Thank you!

[dwh]

It will work at lower power. I've drained my aux battery to totally dead, while my Antec 120mm fan was turned on, a whole bunch of times. No problem for the fan.

Not sure if over-voltage would hurt it, but I would assume it was more likely to than under-voltage. You can limit the voltage with an LM7812 voltage regulator (limiter):

LM7812.gif


Cost about a buck and a half at an electronics supply store. DON'T forget to use a decent sized heat sink for the thing. (A 2" piece cut out of any ol' aluminum channel works well.)


As for the solar...I dunno about that. I have my doubts as to how many watts a 5w or 10w PV will actually produce. Personally, I'd say it was one of those things that just has to be tried to be sure.

Don't forget to tell the rest of us if it works or not.

[dwh]

I just remembered something. Some years ago, someone gave me one of these things:

6473.detail.a.jpg

It was still new in the box. It actually worked - but only if there was a good direct strong direct unshaded direct very bright direct sunlight on it.

In other words, 99.999% of the time, it didn't work.

[bansil]

Ok,we shall see then and I will post results in the next week or so....good or bad

fingers crossed on that .001%

[Lynn]

I'm all for DIY, but have you considered buying a marine solar vent? I've no experience with them, but there are plenty of boat guys around here. Maybe one will chime in...

[brboyer]

Ok,we shall see then and I will post results in the next week or so....good or bad

fingers crossed on that .001%

Depending on the fan specs (the ones I've seen require about .28 Amps) I doubt you will get much functionality from a 5W panel (.28 Amps MAX under ideal conditions)
The solar panel will have to be perfectly clean and pointing directly at the sun in 77 degree (F) temperature at all times to produce that .28 amps then you have to take into account that the ideal sun conditions are only present in most of N.A. for 4.5 hours/day.

The 10 Watt will only be marginally better.

[dwh]

I'm all for DIY, but have you considered buying a marine solar vent? I've no experience with them, but there are plenty of boat guys around here. Maybe one will chime in...

I have considered those. There are quite a few good reviews on that type of vent around the net - though of course, there are plenty of negative reviews as well. If I was building a project from scratch, I would almost certainly use them. I particularly like the fact that they are reversible, so that one can be set to intake, and another to exhaust.

Not cheap though.

There is a Nicro vs. Sunforce debate. As usual, some swear by Ford, and others by Chevy...

http://www.defender.com/category.jsp...5749&id=320600

[bansil]

Those are Bling...alittle rich for me right now...


Since I already have a 4in covered vent installed,no more holes to cut in roof
and 678 cf per hour works out to what 11 cfm?
and the solar panel is maybe 4-1/2 in diam how much output could it have?

So even an 80mm 12v fan moves about 60 cfm and draws about .18A so that would be alot more air movement and the solar output from a panel 10x's bigger would seem to work

Heck I can even try some of the smaller fans that draw 1/2 of that and still move air

This is mainly to vent the vehicle when it sits so no need for opening and closing etc.

and since I have several fans of different sizes and just scored a 10w panel on craigslist for a wopping $10 if it doesn't work out I wont be out anything...except beer drinking time

[wrcsixeight]

I installed a Nicro 4" solar powered vent over a decade ago in my fiberglass roof. The biggest novelty was the no wiring involved. It recharged a battery so the fan ran all night too. About 5 years ago I decided it moved way to little air.

I built a step down ring, from 4.75" to 4 inch diameter and attached a low CFM silent muffin fan to that. Huge improvement. I found the fan blade on the Nicro was just impeding the flow and removed it. Then I used some flexfix tape and covered the solar panel, as the motor itself began clicking back in '06 or something.

Then I installed a bigger fan, and once again, huge improvement, but too loud.

Then I bought a Variable speed Silverstone FM 121 fan, put the speed control in a convenient location, and basically this Fan is always on 24/7/365. Nearly silent at slow speed(.1 amps) and fairly loud at Max(.4) amps.

I have another Muffin fan, which spins the opposite direction. When I turn this fan on, it makes the silverstone quieter, and together they move gobs of air for about .55 amps total.

As I have 200 watts of solar, i am not worried about killing my battery.

I have found some of my fans need almost 6.5 volts to start spinning on their own, but then will keep spinning with as little as 4.5 volts.

Whether it will burn out the fan by not having enough current to get the blades spinning, I cannot say.

But In my opinion, it is best to let the solar panel recharge the battery, and power everything directly from the battery.

[bansil]

Preliminary results are in,it does work

I started at 6am and the sunwas barely up on the mnts.
I set the panel on a table with the fan hooked to it.

I saw it move, when I step to the side it didn't spin it just "loaded" I checked voltage and it was 5v+( idid touch the fan it it started to spin,so I stopped it to see if it would start on it's own)

So I left it and went to work on other things.

I forgot about it and checked on it when I went to get more coffee...it was spinning!!!

16v+ at about 8am and not ideal angle, I tilted it up to point at the sun and the fan went into over drive at 19V it was spinning very fast,I set panel back down and it slowed and I went about the day.
At lunch it was spinning very fast like before with sun straight up.

As clouds rolled during the day I would check it and it was acting like a variable speed fan.

So no idea on long term usage,but no fire and brimstone and it spun 2 4inch fans easily.

So a $5 used panel(panel didn't work when tested at the leads,so I removed the junction box and had voltage...so bad wires=score!) and a few fans, now just have to get everything mounted.

Once spinning it took very little Voltage to keep it spinning.

The fan(s) 12V .28 amp (70 cfm) and .23 amps (67 cfm)(both ball bearing)

The fan was no hotter than anything else out in the 98* sun

This experiment went good(2 days and it stopped spinning and started back up multiple times)

Sorry for no more exotic data