Objectives
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Identify the sun as the main source of the earth’s energy.
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Identify methods of protecting themselves from harmful solar radiation.
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Demonstrate ways to convert solar energy into thermal energy and mechanical energy.
Materials
Background
Every second, the sun gives off more energy than humans have used in all of history. Solar energy is electromagnetic radiation (including infrared, visible and ultraviolet light) released by thermonuclear reactions in the core of the sun.
Only about one billionth of the sun’s energy ever reaches the earth (174 petawatts (PW)) at the upper atmosphere. Approximately 30% of this energy is directly reflected back into space. The rest is absorbed by clouds, oceans and land masses.
With a few exceptions (e.g. nuclear energy, geothermal energy), solar energy is the source of all energy used by humans.
Indirect forms of solar energy include:
- hydroelectricity
- ocean thermal energy
- tidal energy
- wind energy.
The sun also powers the process of photosynthesis, the original source of the energy contained in biomass, peat, coal and petroleum (oil and gas). Usually, however, the term solar energy refers to the portion of the sun’s radiant energy harnessed directly, such as through solar panels.
Solar technologies include active and passive solar techniques:
Active Solar techniques include things such as using photovoltaic panels and solar thermal collectors to convert sunlight into useful outputs.
Passive Solar techniques include things such as orienting a building to the sun and designing spaces that naturally circulate air.
Solar power is often the conversion of sunlight into electricity.
Sunlight can be converted directly into electricity using photovoltaics (PV). Photovoltaics were initially used to power small and medium-sized applications, from the calculator powered by a single solar cell to off-grid homes powered by a photovoltaic array. Solar energy can also be converted indirectly to electricity with concentrating solar power (CSP) systems. CSPs normally focus the sun’s energy to boil water and create steam which is then used to provide power to a generator.
Vocabulary
Energy – The ability to do work.
Solar – Having to do with the sun.
Solar energy – Energy from the sun.
Ultraviolet radiation / Ultraviolet light – Also known as UV radiation/UV light. The sun emits many wavelengths of light, but it’s the ultraviolet waves that cause sunburn. UV light is not visible to humans.
Photosynthesis– The process plants use to make their own food from sunlight and carbon dioxide.
Atmosphere -A thin layer of gas that surrounds the earth. The atmosphere gives us air to breathe and protects us from harmful solar radiation.
Thermal Energy – Heat energy.
Mechanical Energy-Energy in moving things.
Electric Current -Moving electrons.
Pressure -How much an object is pushed on.
Photovoltaic cell -Solar cell which changes light energy into electrical energy. The word “photovoltaic” comes from 2 words. “Photo” refers to light and “voltaic” refers to electricity.
Other Resources
National Energy Board of Canada | About Renewable Energy
British Columbia Sustainable Energy | Solar Photovoltaic
The Canadian Encyclopedia | Solar Energy
BC Hyoro | Conservation
BC Hydro | Sustainability
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