Solar Panels How powerful are solar panels under different conditions? By Andrew Wu and Robert Shekoyan
Question and Purpose Question- How do solar panels perform under different conditions including: Artificial light, direct sunlight, shadow, and window light? Purpose- Determine how shade, glass, and time affects the amps produced by the solar panel in direct sunlight. Determine the relationship between solar panel power output to the distance and wattage of the lamp.
How Solar Panels Work • Silicon, phosphorus, and boron make up solar panels. • The energy from the sun strikes these solar cells. • The energy knocks aside loose electrons. • The panels convert the energy to electricity. • The electricity flows along the panels to whatever they are powering.
Advantages and Disadvantages Of Solar Panels • Pluses • Renewable • Excess energy gives you a credit on your energy bill • Doesn’t pollute (no CO2 emissions) • Works anytime during the day • Lasts a very long time (25 years+) • Minuses • Is not good in bad weather • Is not good in the shade • Very inefficient (only absorbs around 20% of the energy from the sun)
Hypothesis • Since noon is the hottest time of the day and since the • sun is closest to the Earth, the solar panels will produce • more energy at noon than at other times. • We predicted that when the solar panels are closest to the lamp • and the lamp is at its highest power, the solar panels • will perform the best.
Procedure and Materials (This experiment was done on March 30) Materials- Solar panels, ammeter, paper, lamp, camera, tape measure Procedure- Use an ammeter to measure the milliamps (current) produced by solar panels with the following combinations every hour: Indoor, out the window Outdoor, direct sunlight Outdoor, paper covering Outdoor, hand covering
(continued) 1. At 10:00 AM, find a patch of direct sunlight. Set the solar panel flat on the ground. Measure the current in milliamps. 2. Repeat with a piece of paper covering and a hand one in. away in the direction of the sunlight. 3. Go to a window opposite the sunlight. Place the solar panel 0.5 ft. away from the window and measure the current. 4. Repeat with a solar panel 5 ft. away. 5. Repeat for each hour up to 5:00 PM.
(continued) Artificial Light Procedure- • 1. Place two lamps next to each other. They have wattages of 30, 70, and 100 each. • 2. Place the solar panel 8 ft. away from the lamps. • 3. Use different combinations of wattages to reach 30, 70, 100, 130, 170, and 200 watts. Measure the ampage produced by the solar panel for each wattage. • 4. Repeat with 4 ft., 2 ft., and 1 ft..
Change of Current over Time for Different Sunlight Conditions • 2:00 is the best time to get direct sunlight in McLean. • 1:00 was the best time to get any other kind of sunlight including shaded and window sunlight. • The reason noon wasn’t the best time was because on March 30, the day we did the experiment, the solar noon in McLean was at 1:14.
Results: Sunlight (MA stands for milliamps)
Artificial Light: Solar Panel Output under Different Lamp Powers and Distances • The first graph above represents a linear relationship between the wattage of the lamp and the output from the solar panel. • As the distance grows shorter, the output increases. • The second graph shows exponential change. As the distance grows shorter, the output increases by about three times for each halving of the distance.
Conclusion Our hypothesis for sunlight-powered solar panels was wrong, but our hypothesis for electric light-powered panels was right. Solar panels performed best under direct sunlight, with no shadow or covering. Second-best were paper covering and hand covering. The hand and paper both provided shade, which lessened the energy absorption. Third best was the 0.5 ft. away solar panel. The comparison between this and the 5 ft. solar panel shows that distance matters when you build solar panels. The o.5 ft. away solar panel performed 3 to 5 times better than the 5 ft. away solar panel. When the lamp was at higher wattages, the solar panel produced more current. However, it seems like distance is much more relevant than the power of the lamp. At the highest power (200W) and the longest distance (8 ft..), the solar panels produced almost four times less energy than at the lowest distance (1 ft..) and the lowest power (30W).
Background (Part I) When light strikes photovoltaic cells (PV cells), they convert it into energy. PV cells are made of semiconductors, which conduct electricity better than non-conductors but worse than conductors. The most common semiconductor used in PV cells is silicon.
Background (Part II) Silicon atoms contain 14 electrons. They are arranged in three rings. The first has two electrons, the second has eight, and the third has four electrons. Atoms will do anything to fill up their rings of electrons, and a silicon atom’s third ring is incomplete. In a solar cell, silicon atoms share electrons by bonding in a covalent bond. Both share their electrons with each other so that the two silicon atoms both have eight electrons.
Background (Part III: Covalent Bonding) This is an example of a covalent bond. The two oxygen atoms share electrons. Oxygen atoms usually have six electrons in their outer wall, but they share two along the bond.
Background (Part IV) The covalent bonding of the silicon atoms is what forms the crystalline structure in the PV cells. Pure crystalline silicon is a poor conductor of energy, though; its electrons cannot move. Better conductors like copper have electrons that are free to move. Therefore, other atoms are mixed with the silicon, such as boron, with three electrons in its outer wall, and phosphorus, which has five electrons in its outer wall. These atoms could be mixed in at a ratio of one phosphorus atom to a million silicon atoms.
Background (Part V) When those atoms covalently bond with the silicon, for phosphorus there is an electron that is free, creating a negative charge. Electricity flows much better. It is the opposite for boron, with three electrons where there is one more proton. When light strikes the PV cell, some of it is absorbed by the cell. This light knocks some electrons free, and creates electricity. This electricity flows along the impure silicon.