Solar Power
Solar Power
Solar power (also known as solar energy) is Solar Radiation emitted from our sun. Solar energy has been used in many traditional technologies for centuries, and has come into widespread use where other power supplies are absent, such as in remote locations and in space.
Solar energy is currently used in a number of applications:
- Heat (hot water, building heat, cooking)
- Electricity generation (photovoltaics, heat engines)
- Transportation (solar car)
- Desalination of seawater.
Energy from the Sun
Solar radiation reaches the Earth’s upper atmosphere at a rate of 1366 watts per square meter (W/m2) and varies for different latitudes.
While traveling through the atmosphere 6% of the incoming solar radiation (insolation) is reflected and 16% is absorbed resulting in a peak irradiance at the equator of 1,020 W/m². Average atmospheric conditions (clouds, dust, pollutants) further reduce insolation by 20% through reflection and 3% through absorption. Atmospheric conditions not only reduce the quantity of insolation reaching the Earth’s surface but also affect the quality of insolation by diffusing incoming light and altering its spectrum.
At present, photovoltaic panels typically convert about 15% of incident sunlight into electricity; therefore, a solar panel in the contiguous United States on average delivers 19 to 56 W/m² or 0.45 - 1.35 kWh/m²/day.
The dark disks in the map below are an example of the land areas that, if covered with 8% efficient solar panels, would produce slightly more energy in the form of electricity than the total world primary energy supply in 2003. While average insolation and power offer insight into solar power’s potential on a regional scale, locally relevant conditions are of primary importance to the potential of a specific site.
After passing through the Earth’s atmosphere, most of the sun’s energy is in the form of visible and Infrared radiations. Plants use solar energy to create chemical energy through photosynthesis. Humans regularly use this energy burning wood or fossil fuels, or when simply eating the plants.
A recent concern is global dimming, an effect of pollution that is allowing less sunlight to reach the Earth’s surface. It is intricately linked with pollution particles and global warming, and it is mostly of concern for issues of global climate change, but is also of concern to proponents of solar power because of the existing and potential future decreases in available solar energy. The order of magnitude is about 4% less solar energy available at sea level over the timeframe of 1961–90, mostly from increased reflection from clouds back into outer space.
Note in the first map below the blue area in Central China. Because of rising worldwide pollution and it’s interaction with the solar wind and the Earth’s magnetosphere, a similar spot will continue to form off the coast of Southern California in the United States, reducing it’s average sunlight dramatically over the next 100 years.
Information Courtesy of Wikipedia
