How Does It Work? – Here is how photovoltaic cells work. When particles of light, called photons, hit the surface of the cell, electrons are attracted to the surface. As a result, voltage forms between the top and bottom layers of the cell. When an electric circuit is created between these two layers, current flows, which powers electrical equipment.
QUESTIONS: How Does It Work? – The first practical silicon solar cell was demonstrated at Bell Labs on April 25, 1954. Since then, they have not only become a popular and cost effective way to power homes and commercial buildings, they have also been used to power spaceships and satellites.
Is Solar Energy Efficient? – Solar cells themselves, however, are far from efficient. The efficiency rating of a solar panel measures what percentage of sunlight that strikes the panel is actually turned into usable electricity.
QUESTIONS: Is Solar Energy Efficient? – The efficiency of a solar panel is also affected by other factors like panel orientation, the pitch of the roof and panels, the temperature of the panels (which can be controlled somewhat by installing them with a few inches for air flow between the panel and the roof), and the amount of shade to which the panels are exposed.
Solar Photovoltaic – The technology behind solar panels is called Solar Photovoltaic (PV). Solar PV generates energy by converting solar radiation (i.e., sunlight) into direct current electricity using semiconductors.
QUESTIONS: Solar Photovoltaic – The first practical silicon solar cell was demonstrated at Bell Labs on April 25, 1954. Since then, they have not only become a popular and cost effective way to power homes and commercial buildings, they have also been used to power spaceships and satellites.
Solar Thermal Technologies – The word solar refers to the sun. The word thermal means heat. Solar thermal technologies convert heat energy captured from the sun and use it directly for heat or to produce electricity.
QUESTIONS: Solar Thermal Technologies – There two types of solar thermal systems: active and passive. Active solar thermal systems use fans or pumps that move in order to circulate fluids which carry the heat.
Sources of Renewable Energy – Renewable energy is energy from a source that does not run out, or which can be replenished within a human lifetime. Some examples of renewable energy are wind, geothermal, biomass, hydropower, and solar power. The most renewable form of energy is solar energy.
QUESTIONS: Sources of Renewable Energy – Renewable energy is currently being used for about 13.5% of the world’s total energy supply. It also provides 22% of the world's electricity. Renewable energy has become a hot topic in the past decade or so as concerns about climate change and global warming have turned the world's attention to the pollution produced by non-renewable sources of energy like burning coal or oil.
The Discovery of Solar Power – Before 1905, scientists were aware of the photoelectric effect (that light could produce an electric charge) but they could not explain it. Scientists of the time thought that light was a wave moving through an invisible substance called either that was believed to be spread throughout the universe.
QUESTIONS: The Discovery of Solar Power – Though the theory behind solar panels has been understood since 1905, it took nearly 50 more years before a practical application was developed by AT&T’s Bell Labs in New Jersey.
The First Practical Silicon Solar Cell – In 1873, an English engineer named Willoughby Smith discovered the photoconductivity of selenium as he was testing different substances for use in underwater telegraph cables.
QUESTIONS: The First Practical Silicon Solar Cell – Ten years later, American inventor Charles Fritts created the first solar cells made of selenium. Their efficiency, though, was only about 1%, so they had no real practical application.
Solar Energy and Climate Change – The Earth’s climate is changing because of an ever-increasing amount of greenhouse gas (GHG) emissions in the atmosphere. Although solving climate change will likely require a combination of targeted technologies, solar technologies have a huge role to play in curbing emissions.
QUESTIONS: Solar Energy and Climate Change – In manufacturing common materials like aluminum and steel, a large amount of energy is to generate steam or heat water, which is then moved to a boiler vessel.
Solar Energy and the Water Cycle – The water on planet Earth is continually recycled in what is called the water cycle. The water cycle is mainly driven by the sun. Not only does the water cycle move water around the Earth, it also absorbs and moves around solar energy.
QUESTIONS: Solar Energy and the Water Cycle – As liquid water absorbs solar energy, it is transformed into water vapor. This process, called evaporation, absorbs a very large amount of solar energy.
Solar Power and the Economy – Most of the energy used on Earth—from generating electricity, to powering vehicles and industry—comes from fossil fuels. Fossil fuels are the collective name given to substances that have formed in the geological past from the remains of living organisms, like crude oil, natural gas, and coal. F
QUESTIONS: Solar Power and the Economy – That is why there has been so much focus beginning this past century on renewable energy sources. Renewable energy sources like the wind and the sun are free (though of course the technology to convert them to energy is not).