Solar Energy Lab Report

Solar Energy Lab Report


By: Jenzel, Carrie, and Emily

Abstract (Carrie)

For this project, the group created a 31-solar cell line by soldering each cell together through wires. The highest DC voltage obtained in direct sunlight was 12.34 volts, and the lowest DC voltage obtained was indoors without a flashlight, giving off 4.37 volts at most.

Introduction (Jenzel)

When there is a sunny day, the sun shines almost 1000 watts of power per square meter on
the entire planet. So, if we can get all that energy, we can power up the entire planet for no cost at all! Although it is a great alternative to fuel, the question that is being looked into is…how does solar energy work?


Inside a solar panel are photovoltaic cells (photo = light, voltaic = electricity), made from a semiconductor type of material called silicon (Si). A semiconductor has an N-type and a P-type of its element in it. The silicon atom’s valence (or outer) shell is filled with 4 of 8 electrons, so it needs 4 more to be neutral. When sunlight strikes on the solar panel, some electrons are knocked off its bonds, making them move around freely (free carriers). Photovoltaic cells also have either one or more magnetic fields that force the free carriers to move in one direction (called a current). Once wired up to a load (the object that needs to be powered up), the electrons pass through the wire and power up the object.
In order to make the solar panel more efficient, solar panels are doped (adding impurities to an atom) with boron or phosphorous. Silicon mixed with phosphorous take less energy for their electrons to break loose from them because some of the extra phosphorous atoms are not in a bond, and the other atoms beside it aren’t holding it together. So, more than normal electrons break free in that silicon, the silicon becomes N-type. If pure silicon was used, it wouldn’t work as well because N-type silicon is a better conductor.


The P-type silicon is doped with boron, an element that only has 3 electrons in its valence shell. This means that it has more holes, a place where there are no electrons, and they move the same way electrons do. When N-type silicon and P-type silicon are placed next to each other, the electrons in the N-type rush over to the P-type silicon so that it can balance out the charges.


Since the electrons, the N-type silicon becomes positive. So, the electrons try to go back to the N-type where there are holes, but the electric field (made when they crossed to the P-type silicon) prevents them from returning, and now they are stuck. The only way that they can get back is through an external path (wires). The wires are connected to the load, and as the electrons pass through it, it powers up the load with electricity. Once it gets back to the N-type silicon, the P-type is unbalanced again, so they cross to the other silicon and then go back through the wire. This continuous cycle creates consistent electricity, powering up the load with the necessary electricity that it needs to work.
For our project, our final design consists of a line of solar cells, soldered and held together by wires. Our hypothesis for this project is that with a 31-solar cell line, it will be able to create at least 10 volts, hopefully more. Since every solar cell will be hit by sunlight, we will be able to get much more voltage than before, which is why we think that it is a good design. We also believe that it might actually get the mixer to work because with a high voltage, it will be able to power up the mixer.


Parts of a Solar Panel

solar3.gif

A. Cover Glass
B. Anti-Reflective Coating
C. Contact Grid
D. N-Type Silicon
E. P-Type Silicon
F. Back Contact

Materials and Methods (Carrie)

- Broken solar paneling
- Sunlight
- Styrofoam
- Multimeter
- Soldering Iron
- Wires
- Metal Meltable Wire

Steps

1. Solder broken pieces of solar paneling together (the amount used is up to you)
2. Scratch the ribbon wire (the white line on solar paneling) to ease soldering
3. Lay the pieces on Styrofoam for easy and stable soldering, solder in an over-under effect to receive both negative and positive charges from solar cells
4. Make sure to have enough wire on the ends of the panel pieces, to make it easier when connecting to a load
5. Take cells into a source of light (preferably sunlight), and check voltage every now and then until it stabilizes (check every 5-10 mins)
6. Record data in a table, telling how many solar cells were used, and how much DC voltage was produced

Results (Emily)


Using a Flashlight Indoors

Solar Cells Voltage Produced (DC)
2 .762
6 1.308
10 2.022
13 2.669
18 4.10
26 5.10
30 6.36

Without a Flashlight Indoors

Solar Cells Voltage Produced (DC)
1 .10
5 .73
10 1.37
15 2.23
20 2.93
25 3.63
30 4.37

Outside, 2:51 PM

Solar Cells Voltage Produced (DC)
1 .36
5 1.95
10 3.79
15 5.45
20 7.08
25 9.43
30 12.34
Best Results (30 Cells): 12.34 Volts, outside in the sunlight
Worst Results (30 Cells): 4.37 Volts, nighttime and no extra light but the two overhead lights

Conditions were the same for the other test indoors, but a flashlight was used. Using lots of lighting simulated what it would be like during the day. Leaving the solar panels in any source of light made the results more accurate because the voltage stabilized. The 31-solar cell line also lit up an LED indoors with a flashlight. All the solar cells used are different sizes and that affects their voltage. Bigger solar cells cover more area and so more sunlight hits
them.

Conclusions (Jenzel)

Well, when it was tested, it actually ended up getting around 12.5 volts with sunlight, which was a pretty good voltage for us. We only tried to go for 6 volts, and it actually doubled with our new final design that Emily was able to produce. It ended up powering up the LED, but for some reason, it couldn’t power up the incandescent bulb, the motor, and the hot plate. From the hypothesis that we made, it is partly true. We did end up getting more than 10 volts during testing, but it wasn’t able to power up the mixer. So, we were half right on our hypothesis.


Maybe, if we end up getting to redo this project and having more time, we’d probably try to get more solar cells in order to increase the voltage even more. That would probably be able to power up the mixer/hot plate once we get to a certain voltage. Also, our final design didn’t look really neat, so maybe if we found some way to make it look better, that would make it seem more professional.

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