Cooling the planet — one solar panel at a time

By Maddy Yozwiak, Local CorrespondentThu, Mar 26 2009 at 6:26 PM EST

Being a solar energy nerd, I've attempted to answer the million dollar question: how can we make solar panels more efficient? Since the beginning of sophomore year, I've been studying solar in depth as part of a three-year independent science research course at Ursuline (my high school). On Monday, the many hours of research and strenuous dances to the sun god finally paid off: I set up the first stage of my experiment on the roof of the school. (I'm kidding about the sun god dances, by the way. Haven't reached that echelon of nerdom quite yet.)

My research focuses on the ultimate paradox of solar energy — photovoltaic (PV) panels use sunlight to generate electricity. As the PV becomes hot, it produces less electricity. Sitting in the sun all day, the panels become very hot. And so, solar panels and the sun have a love-hate relationship — the very thing that allows the panels to produce electricity simultaneously reduces the production.

Of course, in the winter time or on cold days, the ambient air is sufficient to cool the panels. Likewise, an array that is pole mounted (like this one) or mounted on a rack at an angle (like this lovely example) are cooled by air flow in the space behind the panels. But unless you're the cousin of T. Boone Pickens, you're probably not going to be installing 400 solar panels any time soon. Most domestic installations are mounted directly to the roof for aesthetic reasons — it can actually decrease the value of the house to have a conspicuous array set above the roof angle, despite efficiency gains. Roof mounts recieve no cooling. The four inches or so of space between the roof and the panels is not enough for any air flow. Thus the majority of domestic PV installations aren't producing as much power as they could because the panels simply bake in the sun.

What if there was a way to passively — based on natural convection — cool roof-mounted solar panels? Silicon cells, used in the majority of photovoltaics, have an average power degradation factor of -.5 percent per degree Celsius. So, if the temperature of the panels could be reduced by 10 degrees Celsius, the array would produce 5 percent more power. That translates into hundreds of watts and increased affordibility of solar. Is there a design that could achieve effectively cool the panels by 10 degrees C?

The idea I'm testing is relatively simple: an attached aluminum addition, which is in contact with the back of the panel, with a fin exposed to the ambient air, should cool a PV module and thereby increase its power output. My experiment tests three, 75-watt PV modules: one control, one with an aluminum addition and no fin, and one with an aluminum addition with a fin. A heat sink compound is added between the aluminum and the module. Their temperatures and voltage outputs are being recorded every 15 minutes, in addition to the ambient air temperature, insolation (amount of solar radiation) and wind speed. Check out some pictures of Maddy's Solarfest 2009!

This is Dr. Loxsom and myself on the roof of the school. Not going to lie, I felt pretty cool up there. The metal-tripod thing is the data logger. The modules, from left to right, are experimental 2 with the fin, experimental 1 without the fin, and the control.

Notice the convenient location of the American flag. I'm thinking I should send this picture to President Obama ...

This is the back view of the experimental 1 panel — aluminum addition without the fin. At the top, the little black box, is the junction box to which the voltage sensor is wired. The black piece of tape in the middle holds down the temperature sensor to the panel.

This is a top view of the racking set-up. The black blocks are foam bricks, to prevent any drilling into the roof. Normally, the silver, vertical pieces would be attached directly to the roof.

This is a view of the three panels. On the furtherst panel to the right, you can see the exposed aluminum fin.

Will it work? Early data looks promising. But this is science, after all, so I'm not going to count my Watts till they're produced ... Don't worry, I'm not going to leave you on a cliff hanger. I'm no TV producer. By March 30, the experiment will be complete and I'll fill you in on the juicy details!

The story behind my project is a pretty funny one. Both my parents studied solar energy in Texas after college; they actually met there. (Cue the aw from all the tree-huggers!) Their thesis advisor, Dr. Fred Loxsom, is now the chair of Sustainability at Eastern Connecticut State University. Dr. Loxsom generously agreed to be my mentor, and he has been nothing short of utterly essential in helping design the experiment. Of course, solar panels are certainly not cheap. For a while, I considered robbing a bank to fund my project — no one would notice it on a transcript, right? Luckily, Lloyd Hoffstatter saved me from a life of crime. Mr. Hoffstatter is one of the founding partners of Mercury Solar, the leading solar panel installer in New York. And guess what? He studied under Dr. Loxsom with my parents as well. Mr. Hoffstatter graciously lent me three panels to test and donated the racking needed, while Dr. Loxsom brought down an awesome data logger set-up. As they say, it takes a village to test solar energy.

(Well, it's not quite Letterman material, but I try.)

Monday was a brutally windy day to build the experiment (my fingers still have not quite regained feeling), and I'll definitely post the video about it soon. If you're interested in solar energy in New York, check out this site. It lists the rebates and other incentives available for solar systems.

I'll leave you with a solar joke:

Three men were in a NASA conference room to decide how to spend $10 billion.

“I think we should put our men on Mars!” said the first man.

“Ooh, good idea,” said the other two.

“I think we should put our men on Venus!” said the second man.

“Ooh, good idea,” said the other two.

“I think we should put our men on the Sun!”

“How are you going to do that?”

“Easy. We go at night.”

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Scoffer 09/16/2010 00:39 AM

I have successfully put a permanent water cooling system in one of my 65W , 1M x 0.5M arrays for testing. Its now been working for about 18 months without any real problems.
Design: -
Home made UV stabilised and high melting point strong water bladder that fits under the PVs. depth of 30mm from frame to underneath of PV. Some improvisation and plastic welding needed.
The bladder is connected to an inlet and outlet tube. The outlet tubes - 3x25mm,rise approx 0.5 Metres from.... More

San Diego Roofers 08/02/2010 18:45 PM

A heat sink compound is added between the aluminum and the module.

Mono 07/04/2009 14:07 PM

I try to sold solar power to big company before this, they pay us only .000007 cent per kwh. This very cheap when compare with solar panels and other utility solar panels price (battery, base, installation). 1 year after we deploy solar panels, we design to sold all solar panels out because of maintenance cost (heavy win).

Solar Punch 05/19/2009 15:45 PM

Maddy, do you have an update to your solar research? We'd love to know your results. Thanks,

Alan
http://www.solarpunch.org

myozwiak 05/28/2009 10:54 AM

Thanks Alan! Yes, I recently just published a new post about the results and the beginning of the second stage. I should have even more results soon - and I love the band!

Solar Punch 06/30/2009 23:29 PM

Maddy, thanks for posting the update from your project. Your research process sounds way too familiar (I'm a research scientist by day). But that's what the "re" in "research" is for: redo!!!

Glad you like our Solar Punch. I wanted to let you know of an upcomming gig we have at the Greenburgh Nature Center on July 12 from 3-5pm: .... More

http://highplainswindandsolar.com/ 04/07/2009 02:34 AM

this site gives you information about all solar and wind product

Solar panel | Solar Energy | Solar Roofing Panel 04/07/2009 02:27 AM

this site is very informative.

Solar panel | Solar Energy | Solar Roofing Panel 04/06/2009 20:26 PM

Solar systems work when sunlight strikes a solar photovoltaic module and excites electrons trapped in the silicon solar cell. The electrons travel through wires on the back of the solar panel and into your house, to be used immediately or sent to your electric utility.Most places in the high plains have plenty of solar energy available to meet some, or all of your needs. Homes located in areas with ample sunlight, where electricity prices are high, or where access to
the electric grid is.... More

Lauren Buchholz 04/04/2009 15:23 PM

Awesome! Best of luck with your experiment. Thanks for sharing about PV panels. I wasn't aware of the necessity for cooling, but it's good to know: another one of the ways in which we can make going green even greener. I'll have to keep that in mind if I ever get my own solar array. Looking forward to seeing how things turn out!

myozwiak 05/28/2009 10:56 AM

Hi Lauren - yes, solar is cool, isn't it? : )

Cooling the planet — one solar panel at a time

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