Solar Energy Samara Angel, Emilie Harold, Elyssa Hofgard, Jules Pierce, Joyce Xu

Solar Thermal vs. Photovoltaic Energy Solar heating panels = solar thermal Solar thermal energy: concentrates light from sun to generate heat heat runs engine engine runs generator for electricity Efficiency: 30-40% Easy to store energy => effective for large-scale energy production

Solar Thermal vs. Photovoltaic Energy PV cells directly convert sunlight into electricity Traditionally made of silicon Photons (from sunlight) strike & ionize semiconductor material, causing outer electrons to break free Storing energy is impractical/inefficient/expensive, so only useful during the day Lower upfront cost & lower maintenance

Solar Power Incident sun releases a constant amount of radiation at a given time of the year, the amount of radiation that reaches the Earth’s atmosphere in a given location is constant seasonal variation: the Earth has an elliptical orbit, so the distance between the Earth and sun changes throughout the year, so the amount of radiation that reaches the Earth’s atmosphere changes

Solar Power Incident on Earth’s Surface solar power incident on Earth’s surface: amount of solar radiation that reaches the Earth’s surface in a given unit of area measured in mW/cm 2 (radiation per unit of area squared) amount of energy that gets through the atmosphere is affected by atmospheric factors absorption, scattering, water vapor, clouds, pollution, latitude regional variation: these factors vary around the planet, which accounts for the regional variation in the solar power incident

Definition of the Solar Constant ● Large amount of energy in nuclear fusion reactions from sun ● Solar Constant: the amount of solar radiation across all wavelengths present in 1 meter at 1 second at the average distance from the sun to the earth ● The solar constant is 1400J every second per square meter and represents 5.5x10^-10 of all the energy output from the sun

Variation in the Solar Constant ● Varies by.1% during its 11yr sunspot cycle ● Elliptical orbit of the Earth changes the distance from the Earth to the sun and causes a 7% variation ● Longer cycles ( of years long) occur as well

Albedo and the Solar Constant ●Solar constant-measure of the amount of energy at the top of the atmosphere ○As this energy travels through the atmosphere, it is absorbed and reflected by different surfaces. ●Albedo-the extent to which a particular surface can reflect energy ○ratio of the light that a surface reflects to the total amount of light that falls on it

Specific Values grass asphalt fresh snow old snow ocean surface- 0.06

Albedo Variation Varies daily depending on the time of day and the angle of the sun hitting the surface. Varies with latitude because of the angle of the sun hitting the surface. Also varies with different reflective materials at different latitudes and climates eg. Sea ice has a higher albedo than open ocean water As the surface characteristics change throughout the seasons, so do the albedo values. During the winter, the amount of snow in the higher latitudes increases, so the albedo values increase. Average value of Earth’s albedo-0.39

Works Cited ● al%2Fenergy-project-book-info.pdfhttps://docs.google.com/viewer?url=https%3A%2F%2Fwww.fairviewhs.org%2Fsystem%2Ffiles%2F32843%2Forigin al%2Fenergy-project-book-info.pdf ● ● ● ● ● ● ●

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