Cooling off PV panels??

Xringer · 07-29-10, 12:50 PM

I've seen some water-cooled PV rigs. They use the hot water to pre-heat hot water for the house.
SunDrum: A Turbocharger for Solar Systems:Greentech Media

I know my PV panels are warmer on the bottom side (on a hot day), so I've been thinking
about the possibility of gluing some heat sinks on the bottom side..

But, a bunch of those things can get heavy.. So, what I'm wondering is,
is there a light-weight, stick-on heat radiator??

I've been thinking of thin aluminum sheet bent to form little cooling points..
--^--^--^--^--^--^--^--
Seems like it would be hard to do by hand..

Any ideas??

Piwoslaw · 07-29-10, 02:50 PM

So SunDrum is just starting to market solar hybrid systems? I thought they were already available.

I think the aluminum sheet may be worth experimenting with. Maybe slap on a small fan, too? If the fan needs 5-10 watts, but increases output by 10-20W, then it's a win.

Daox · 07-29-10, 04:12 PM

How much does the heat really effect the power output?

Xringer · 07-29-10, 04:13 PM

I was thinking of fans, but used with sheets of coroplas.
The coroplas would be used to cover most of the back side of the panels and little
PC type fans would be placed on the high sides to pump out the hot air,
replacing it with cooler fresh air, from input vents closer to the ground.

I'm not sure how good that would work.

Maybe just sticking 36 little CPU heat sinks on the back of each cell location, would have some cooling affect..?.

144 little heat sinks hang down in the shade of the panels.?.

I wonder if the panel substrate is a good conductor?
It might work, if the heat in the area around a heat sink would travel to the sink from a few inches around it..

Because the bottom is hotter than the top surface, leads me to think the bottom does not really radiate heat very well..

Xringer · 07-29-10, 04:32 PM

Quote:

Originally Posted by Daox

How much does the heat really effect the power output?

I think it depends on how hot the panel gets, what type of panel it is,
(mine is multicrystalline), air temperature etc.

Effect of Temperature

I'm not sure about mine, but I 'think' maybe the power jumped up
about 40 watts above normal, once, right after a quick rain shower.
I could be wrong, but it seems like cooler might be 8 or 10% better with my array..
I'll find out for sure, when the winter comes..

Piwoslaw · 07-30-10, 01:10 AM

Quote:

Originally Posted by Xringer

I'll find out for sure, when the winter comes..

But there is less energy from the sun during winter. I'm not sure how much less in your location, but here we get 886 W/m2 in the summer, but only 12.4 W/m2 in the winter, according to a source I found.

Xringer · 07-30-10, 07:44 AM

Dang! 'Projection effect'.. Insolation - Wikipedia, the free encyclopedia

I just ran the numbers at:
Solar Calculator : Weather Underground

Not so good.. Maybe I should store these panels for the winter..

Anyways, I've figured out how to test for any 'cool' gain. On a really hot sunny day (soon),
I'll use the water hose (set to mist) and slowly cool the bottoms of the panels.
Then, I'll switch to 'car wash' mode, let my wife take over on the nozzle
and go measure the current at the load..

If there is a nice gain, then I'll keep looking into PV coolers..

Before we do this, I want to get my new Red Rock Tracker board installed.
It might be in the mail, or it might not.?. I don't know anyone who owns
a RedRock board, so I have no idea about delivery times.

Solar Mike · 08-01-10, 04:28 AM

How about running some tubing across the upper half of your array and mist spray water across them using those pot plant mini spray nozzles. As long as its a fine mist so the glass doesn't crack with sudden changes in Temp. This must have been tried before by someone.

Xringer · 08-01-10, 07:58 AM

That would be okay for testing, but long term, it would end up leading to problems
with the steel mount frame, aluminum PV frames, mineral deposits & the water bill..

Of course, the grass would be greener under the solar panels..

I should get busy and build the MPPT (Manual PPT) project and squeeze some extra power that way..
I have most of the parts now, but my bench is loaded with other work right now.
Maybe I should rearrange things so that hobby items are pushed to the top of the list..?.

Xringer · 08-02-10, 10:52 AM

Interesting event today.. It's a dry 75F today and the clouds are keeping the area cool,
and when the sun comes back, the panels must be pretty cool, because
today is the first time I've ever seen such high currents. 6.8 to 7.0 Amps..
6.5 to 6.6 is the normal range when it's sunny.

7 amps is about 490 watts (inside, at the load). So, with the line losses,
these panels are pretty close to their rated 500w today (during peaks).

Heck, maybe they will run 500w on real hot days, with some MPPT..

07-29-10, 12:50 PM	#1
Xringer Lex Parsimoniae Join Date: Feb 2009 Location: Woburn, MA Posts: 4,918 Thanks: 114 Thanked 250 Times in 230 Posts	Cooling off PV panels?? I've seen some water-cooled PV rigs. They use the hot water to pre-heat hot water for the house. SunDrum: A Turbocharger for Solar Systems:Greentech Media I know my PV panels are warmer on the bottom side (on a hot day), so I've been thinking about the possibility of gluing some heat sinks on the bottom side.. But, a bunch of those things can get heavy.. So, what I'm wondering is, is there a light-weight, stick-on heat radiator?? I've been thinking of thin aluminum sheet bent to form little cooling points.. --^--^--^--^--^--^--^-- Seems like it would be hard to do by hand.. Any ideas??

07-29-10, 04:12 PM	#3
Daox Administrator Join Date: Aug 2008 Location: Germantown, WI Posts: 5,525 Thanks: 1,162 Thanked 374 Times in 305 Posts	How much does the heat really effect the power output? __________________ Current project - To view links or images in signatures your post count must be 0 or greater. You currently have 0 posts. To view links or images in signatures your post count must be 0 or greater. You currently have 0 posts. & To view links or images in signatures your post count must be 0 or greater. You currently have 0 posts.

07-30-10, 07:44 AM	#7
Xringer Lex Parsimoniae Join Date: Feb 2009 Location: Woburn, MA Posts: 4,918 Thanks: 114 Thanked 250 Times in 230 Posts	Dang! 'Projection effect'.. Insolation - Wikipedia, the free encyclopedia I just ran the numbers at: Solar Calculator : Weather Underground Not so good.. Maybe I should store these panels for the winter.. Anyways, I've figured out how to test for any 'cool' gain. On a really hot sunny day (soon), I'll use the water hose (set to mist) and slowly cool the bottoms of the panels. Then, I'll switch to 'car wash' mode, let my wife take over on the nozzle and go measure the current at the load.. If there is a nice gain, then I'll keep looking into PV coolers.. Before we do this, I want to get my new Red Rock Tracker board installed. It might be in the mail, or it might not.?. I don't know anyone who owns a RedRock board, so I have no idea about delivery times. Last edited by Xringer; 07-30-10 at 08:27 AM..

08-02-10, 10:52 AM	#10
Xringer Lex Parsimoniae Join Date: Feb 2009 Location: Woburn, MA Posts: 4,918 Thanks: 114 Thanked 250 Times in 230 Posts	Interesting event today.. It's a dry 75F today and the clouds are keeping the area cool, and when the sun comes back, the panels must be pretty cool, because today is the first time I've ever seen such high currents. 6.8 to 7.0 Amps.. 6.5 to 6.6 is the normal range when it's sunny. 7 amps is about 490 watts (inside, at the load). So, with the line losses, these panels are pretty close to their rated 500w today (during peaks). Heck, maybe they will run 500w on real hot days, with some MPPT.. Last edited by Xringer; 08-02-10 at 10:55 AM..

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07-29-10, 02:50 PM	#2
Piwoslaw Super Moderator Join Date: May 2009 Location: Warsaw, Poland Posts: 961 Thanks: 188 Thanked 110 Times in 86 Posts	So SunDrum is just starting to market solar hybrid systems? I thought they were already available. I think the aluminum sheet may be worth experimenting with. Maybe slap on a small fan, too? If the fan needs 5-10 watts, but increases output by 10-20W, then it's a win.

07-29-10, 04:13 PM	#4
Xringer Lex Parsimoniae Join Date: Feb 2009 Location: Woburn, MA Posts: 4,918 Thanks: 114 Thanked 250 Times in 230 Posts	I was thinking of fans, but used with sheets of coroplas. The coroplas would be used to cover most of the back side of the panels and little PC type fans would be placed on the high sides to pump out the hot air, replacing it with cooler fresh air, from input vents closer to the ground. I'm not sure how good that would work. Maybe just sticking 36 little CPU heat sinks on the back of each cell location, would have some cooling affect..?. 144 little heat sinks hang down in the shade of the panels.?. I wonder if the panel substrate is a good conductor? It might work, if the heat in the area around a heat sink would travel to the sink from a few inches around it.. Because the bottom is hotter than the top surface, leads me to think the bottom does not really radiate heat very well..

08-01-10, 04:28 AM	#8
Solar Mike Helper EcoRenovator Join Date: Apr 2010 Location: Wellington, New Zealand Posts: 61 Thanks: 0 Thanked 6 Times in 5 Posts	How about running some tubing across the upper half of your array and mist spray water across them using those pot plant mini spray nozzles. As long as its a fine mist so the glass doesn't crack with sudden changes in Temp. This must have been tried before by someone.

08-01-10, 07:58 AM	#9
Xringer Lex Parsimoniae Join Date: Feb 2009 Location: Woburn, MA Posts: 4,918 Thanks: 114 Thanked 250 Times in 230 Posts	That would be okay for testing, but long term, it would end up leading to problems with the steel mount frame, aluminum PV frames, mineral deposits & the water bill.. Of course, the grass would be greener under the solar panels.. I should get busy and build the MPPT (Manual PPT) project and squeeze some extra power that way.. I have most of the parts now, but my bench is loaded with other work right now. Maybe I should rearrange things so that hobby items are pushed to the top of the list..?.