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.”