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-   -   Cooling solar panels.. (https://ecorenovator.org/forum/showthread.php?t=2499)

Fordguy64 10-31-12 01:22 PM

Cooling solar panels..
 
So while at work today I was thinking.. Going off the info of when solar panels get hot they become less efficient. That if you attached copper pipe to the back of the solar panel you could possibly heat water and cool the solar panel?? I'm not sure how hot the back of solar panels get tho? Just a thought anyone have any input? As I have not seen anyone do anything like this

Xringer 10-31-12 02:22 PM

Over the last few years, I've seen a few combo panels around,
but since they are integrated into one unit, they aren't a big seller..

#1. After the company fails, you are stuck with a combo panel you can't repair. (no parts).
#2. Combo panels are costly. It might be cheaper to install two systems.
#3. Complexity means more things to go wrong.

Since the back side of my PV is hotter than the sunny side, I've wondered about cooling them,
by attaching a DIY hot water heat exchanger under the panels.

Seems like a lot of work to attach the HX units to each panel,
when I could build HW panels (or buy used HW panels) for a little more $$.

The complexity builds up if you live where it gets below 32F..
Now you need anti-freeze water, instead of tap water.
That means a double-wall HX (to meet code).


One other problem with using a closed loop system. When the storage tank water gets really hot,
Then fairly hot water is going to be pumped into the HX.
That's going to mean the PV is not going to see a lot of cooling.
So, the big PV cooling gain might not be there..
(Unless you use a bunch of hot water)..
:rolleyes:

IMHO, Not really feasible for the average DIYer..

One of the best ways to get more power out of your PV is to cut down all the trees that shade your panels.. :p
Another way to get more juice is to make your elevation adjustable.
So you can tweak the angle to match the season..

I don't recommend a DIY solar tracker, unless you keep the PV under 500w.
Gets too complicated with big arrays..

ecomodded 10-31-12 06:51 PM

How about making a solar heat panel with the back of the PV panels as heat exchangers. They could act as a pre-warmer for a Purpose built Solar heat exchanger.

Xringer 10-31-12 07:27 PM

They do make combination panels..

http://gravitaslc.com/Blog/wp-conten...Solimpeks1.jpg
Solimpeks PV-T Hybrid Collectors | SOLIMPEKS Solar Energy Corp.


They just aren't practical.. I think the warranty on this type of panel is likely
only 5 to 10 years. The standard PV panels are for 2 or 3 times as long.


This kind of "hybrid" panel isn't ready for prime time.
Kinda like the Solar Powered car.. Not practical.

http://www.solarkinguk.com/wp-conten...2/03/car-1.jpg

ecomodded 10-31-12 10:49 PM

It would be fairly easy to make a homemade shallow box to mount to the back of the PV panel. Each panel would need its own intake vent/hole , sharing a single inline fan for pulling air threw them. A big array, 2,000,3,000 or 4,000w or better would make for a serious heater. A smaller amount of PV panels could act as a pre warmer for the Solar collectors.

I am going to explore this avenue.

Xringer 11-01-12 12:48 AM

IIRC, the backside of some of my PV was up around 120 to 150F.

You might not need to mount each panel as the lid of an air-box.
Maybe just mounting them pressed up against each other would work.
Then, you could build a little 4" wall around the outside edge of the array. One big hot air collector box!
http://www.eco-buildingproducts.com/...r%20Array.jpeghttp://ecofriend.com/wp-content/uplo...roof_o9z4d.jpg

Blow cool house air into the bottom of the array (spread it with manifold dams)
and suck heated air out the top..

Just what I need to heat my basement in the winter time..

Summer might be a problem..

Ryland 11-01-12 02:22 AM

How much is the output dropping? 10% or so on a hot day? on a 1kw system that is $200 worth of panels that are more or less being cut out of your production, as I see it you can either spend that $200 on another panel, or you can spend it on a roll of copper pipe... then another $200 on a pump, $500 on a storage tank and the list goes on and on! or you can buy another panel and get more output all of the time!

Xringer 11-01-12 07:57 AM

Yeah Rayland! The lowest cost way to pick up some extra power is to add more PV.
That's what the experts tell people when they start talking about trackers.

I've seen some large tracking system prices, where the tracker hardware price
was about equal to the cost of the panels.

Fordguy64 11-01-12 06:43 PM

very good info guys :)

Ryland 11-01-12 10:54 PM

Right, trackers make sense when you have very limited space and need to do things like put your panels on a pole to get at the sun, at that point you might as well put them on a tracker as well.

Cooling your panels adds cost, weight, complexity and isn't going to be a great way to get hot water because the panels aren't getting hot enough, so you end up getting expensive warm water.


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