(RHIE) Solar Power Lesson

Solar Power

Energy from the sun

The sun has produced energy for billions of years.  Solar energy is the sun's rays (solar radiation) that reach the Earth. This energy can be converted into other forms of energy, such as heat and electricity.

Solar energy can be used for heat and electricity

When converted to thermal (or heat) energy, solar energy can be used to-

    • Heat water — for use in homes, buildings, or swimming pools
    • Heat spaces — inside homes, greenhouses, and other buildings
    • Heat fluids — to high temperatures to operate a turbine to generate electricity

The main benefits of solar energy are-

    • Solar energy systems do not produce air pollutants or carbon-dioxide
    • When located on buildings, they have minimal impact on the environment

Two limitations of solar energy are-

    • The amount of sunlight that arrives at the Earth's surface is not constant. It varies depending on location, time of day, time of year, and weather conditions.
    • Because the sun doesn't deliver that much energy to any one place at any one time, a large surface area is required to collect the energy at a useful rate.

Solar energy is sunshinesolar panels on a roof

The amount of solar energy that the earth receives each day is many times greater than the total amount of energy consumed around the world. However, solar energy is a variable and intermittent energy source. The amount and intensity of sunlight varies by location, and weather and climate conditions affect its availability on a daily and seasonal basis. The type and size of a solar energy collection and conversion system determines how much of available solar energy can be converted to useful energy.

Solar thermal collectors

Low-temperature solar thermal collectors absorb the sun's heat energy to heat water or air for heating in homes, offices, and other buildings.

Solar Thermal Power Plants

solar thermal power plantsSolar thermal power uses solar energy instead of combustion

Solar thermal power plants use the sun's rays to heat a fluid to very high temperatures. The fluid is then circulated through pipes so it can transfer its heat to water to produce steam. The steam, in turn, is converted into mechanical energy in a turbine and into electricity by a conventional generator coupled to the turbine.

Solar Thermal Collectors

Heating with the sun's energy

Solar thermal (heat) energy is often used for heating water used in homes and swimming pools and for heating the insides of buildings ("space heating"). Solar space heating systems can be classified as passive or active.

Passive space heating is what happens to your car on a hot summer day. The sun's rays heat up the inside of your car. In buildings, the air is circulated past a solar heat surface and through the building by convection (meaning that less dense warm air tends to rise while denser cool air moves downward). No mechanical equipment is needed for passive solar heating.

Solar Energy & the Environment

An array of solar photovoltaic panels supplies electricity for use at Marine Corps Air Ground Combat Center in Twentynine Palms, California

Using solar energy produces no air or water pollution and no greenhouse gases, but may have some indirect negative impacts on the environment. For example, there are some toxic materials and chemicals that are used in the manufacturing process of photovoltaic cells (PV), which convert sunlight into electricity. Some solar thermal systems use potentially hazardous fluids to transfer heat. U.S. environmental laws regulate the use and disposal of these types of materials.

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