Solar Panel Project

The solar cells wired together resting on blue foam

Yesterday was my last day at college. I spent the morning moving out and the rest of the day in the Academic Center working on the solar panel.  My goal was to build a low-cost USB solar panel that could be mounted on the top of my rear rack to charge cell phones, cameras and other electronics while we were biking.


Earlier in the week I had spent many hours soldering the individual cells together.  The top of each cell is negative charge, while the bottom is positive.  Thus, I had to string the tops and bottoms of adjoining cells to have the voltages add in series.  Each cell produces about .5 V, so the panel ideally would put out 6 volts in direct sunlight.  However, the cells are very brittle and I chipped a lot of corners in the process of wiring them, so they probably put out less than .5V each.

Each USB head has 4 pins.  Pin 1 connects to 5V and Pin 4 connects to ground.  Pins 2 and 3 are data pins, and depending on the voltage that they detect in each pin the iphone can tell if it is being plugged into the wall or the computer.  For non-apple products the data pins can usually be ignored.

After a lot of research, I ended up building a very simple circuit.  The circuit included a 5V voltage regulator, a diode and a few resistors to connect to the data pins.  Since the voltage coming in from the solar panels is variant depending on the intensity of the sun, the voltage regulator is needed to buck or amplify the voltage to make sure it is exactly 5V.  The diode makes sure current only flows one way so there is no back flow into the panels.

The Circuit and the USB connector

After building the circuit, I moved on to preparing an Altoids tin to house the wires.  I cut out a space on the side to have the female USB head exposed to make plugging in easy.

The circuit housing box with a cut-out for the USB input

Finally, I laid up carbon fiber around the edges to strengthen the panel and prevent the blue foam from shredding if it got banged around.  The carbon fiber also reinforced the brass hooks that were stuck into the foam that would be relied on to mount the panel on the bike. I rubbed epoxy on top of the cells to glue them to the foam and hopefully protect them so they didn't break as easily.

The final solar panel

Alright, so it is a bit sloppy looking and may or may not actually work.  It was raining the day I finished it so I couldn't test it.   I will update this post once I test it!

 In the meantime, I am finishing up ordering gear and finding campsites along our route.  In the next few days I will lay out all of the gear on my floor and try to pack it all....

End of the Year

What an amazing week!

I finished my last final on Thursday, and since then my days and nights have been filled with crazy excursions, deep conversations, great people and anticipation.

Friday was Olin's carnival- we played on bouncy arenas and inflatable obstacle courses, ate grilled cheese and listened to many of Olin's multi-talented musicians sing in various bands and ensembles.  The highlight was probably some impromptu boxing between the dorms, with sideline cheering from a Babson Police woman and the people who ran the carnival floats.  Later, we had a school-wide bonfire near the soccer fields, made s'mores and roasted hot-dogs on sticks.  After the fire was put out, Janie, my friend Ben and I lay on the grass for another hour looking at the stars and singing James Taylor, Simon & Garfunkel, Joni Mitchell, and Cat Stevens.  The night ended as one of my best friends, Alec, and I sat on my bed talking about everything and listening to This American Life as we both fell asleep.

(Photo Courtesy of Chris Gallello, Olin College '12)

On Saturday I played in an ultimate Frisbee tournament all day, running up and down the fields until I literally couldn't walk straight.  Then I came back and went on a 5 mile walk with a group of adventurous folk: Jess, Geoff, Kelsey, Diana, Boris and Nathan.  We walked to this cool spot in the Needham town forest where someone built a toy train track, a bench, a table, birdhouses, and a space for geocache.  I'm pretty sure we walked in circles for awhile before finding our way back, but I didn't mind.  When you come home and your feet are so sore every step is terribly painful you know you have had a successful day.

Yesterday, my friends Kate, Ingrid, Diana and I went swimming in a beautiful pool at Wellesley College.  We meant to go somewhere else after, but instead sat in the sauna discussing feminism.  I'm so lucky to be friends with such strong, smart, and independent women.  

Kate and I started running a week ago.  We have been going nearly everyday, increasing our distance and decreasing our time every run.  She ran cross-country in high school, so she is mixing in sprint days and hill days as we get back in shape.  It has been fun to track our progress and feel really good about all the effort we are putting in to our health.

Today we had the most amazing flash rain.  Everything was perfectly timed- I felt a slight drizzle as I left the academic center and walked towards the dorms after the last student presentations at EXPO (an end-of-semester showcase of student projects at Olin).  Kate and I changed into our running clothes and ran out in a sprint as it started to downpour to the cheers and encouragement of people watching and guys playing shirtless frisbee on the great lawn.  Our shoes were soaked through before we had gone 100 feet.  We ran 4.5 miles through the pouring rain, whooping and proclaiming our joy.  The trails were soaked and beginning to flood, and we ran through every puddle.  Running in the rain is probably one of the most exhilarating things ever.  You don't notice your sweat or your fatigue- every part of your body becomes one with the raindrops and the earth that you are running on.  And when you get back you feel like a champion.

But all these activities could have just came and went, been fun but not really memorable.  What has made it awesome are all the amazing people I have become friends with this year and who have become part of my life.  I think that is what is going to make this summer incredible- all the people that we will connect with at each stop and that will be generous with us beyond what we could ever imagine.  

Life is pretty incredible, all of the time. We leave in 20 days!