Author Topic: Fan Cooling Panels  (Read 1745 times)

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george65

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Fan Cooling Panels
« on: September 15, 2016, 05:22:15 AM »

Been reading about the drop off in panel output due to heating and cooling panels by water misting and Thermo Syphoning of the air space underneath.

From other interests I have come to see the vast difference in passive cooling to forced air cooling.  Water cooling seems to have a lot of possible drawbacks but I'm wondering if anyone has tried  fans under the panels to cool them and raise efficency to a point where the fan is powered and there is still a surplus gain of energy Produced.

I'm thinking about a fan from a car radiator. These things are very powerful  ( and power hungry) but do produce what I think would be very useful airflow for this purpose at quite low current draws.
I'm reading that the heating of the panel can reduce output by 10-20%. On a 250W panel, that is 25-50W. Seems quite a bit especially if you have 5KW of panels!
I have been testing a couple of different car fans and can get a good air movement at only 10W power draw using a small bulb for a resistor.

I'm wondering if anyone has tried this and if cooling the back of the panel is effective or is it the front that needs to be cooled? From my understanding, efficiency wise the back would be better.

I'm thinking that if a car fan was placed at the bottom of a panel and tilted at an angle to hit the back of the panel and the one stacked above it, that there may be sufficient cooling to gain a net increase in production.

The other thing I'm thinking is that each panel has some thing like a large computer fan blowing along it to forcably move the air and di it before the panel heated up in order to make the thermo syphoning work. I know from experience, draft can be one thing but a computer fay drawing next to no power can easily produce more airflow and cooling capability.

I come back to the thought though that inefficiency in anything solar seems to be the most efficient way.  Rather than do anything to add efficiency in solar like tracking or other things, the best road seems to be just spend the money on more panels running equally inefficiently. Trying to eliminate the inherent problems seems to not have much payback and the best thing to do is just live with the problems and add more panels to compensate for them.

Given the low cost of the fans and small power consumption, I'm thinking this may actually be worthwhile?
Any thoughts or experience with this?

thirteen

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Re: Fan Cooling Panels
« Reply #1 on: September 15, 2016, 11:56:05 AM »
Idea. Set up a box fan or smaller fan using cardboard boxes and direct the air flow under a couple of panels. You may need to cover some between the panels for air movement. Sort of a test record the results. With the cardboard you could redirect things easily. I do not have that problem. Would it work to just raise the panels up higher? I assume these are on a roof.  Just a quick idea 13
MntMnROY 13

DamonHD

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Re: Fan Cooling Panels
« Reply #2 on: September 15, 2016, 12:17:02 PM »
Water under the panels is also called "PV/T" or "PV/Thermal" so you end up getting improved PV performance *and* warm or hot water.  You can balance electrical performance against heat performance by choosing the return temperature.

Various people make them.

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OperaHouse

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Re: Fan Cooling Panels
« Reply #3 on: September 15, 2016, 01:49:39 PM »
You may gain some hot water, but I doubt there will be much electrical gain because temps are still quite hot.  Get them down below freezing and there is an advantage.  I need to measure the temps of my panels sometimes.  If it was worth doing, everyone would do it.  This question has been coming up for 20 years.  Spraying water on them will likely reduce output.