Key Terms

Descriptions are taken from Works Cited.

Active Solar: Stores electricity. A charge controller keeps the battery charged.

Battery System: Use of solar energy (such as for radiant heat) that requires mechanical equipment (such as solar collectors, pumping systems, and storage batteries).

Biosphere: The part of the Earth’s crust, waters, and atmosphere that supports life. The ecosystem comprising the entire Earth and the living organisms that inhabit it.

Bureau of Land Management (BLM): U.S. government agency that manages public lands. Balances the needs of many people AND protects the land and resources. Considers social, economic, and environmental impacts of activities that occur on specific public lands. (see also Land Use Plan)

Carbon Cycle: The circulation of carbon between living organisms and their surroundings. Carbon dioxide from the atmosphere is synthesized by plants into plant tissue, which is ingested and metabolized by animals and converted to carbon dioxide again during respiration and decay.

Carbon Dioxide (CO2) Gas: Created from the hydrosphere through degassing, or from land animals and soil through respiration, or from the lithosphere through the combustion of fossil fuels.

Carbon Footprint: A measure of the amount of carbon dioxide released into the atmosphere by a single endeavor or by a company, household, or individual through day-to-day activities over a given period.

Concentrated Solar Power (CSP): A solar system that uses mirrors (or other reflecting devices) to collect solar energy. Solar radiation must be very concentrated to generate electricity. Requires a continuous supply of strong sunlight.

Conversion Efficiency: The proportion of radiant energy that the cell converts into electrical energy relative to the amount of radiant energy that is available and striking the PV cell. Improving conversion efficiency is vital to making PV energy more competitive.

Dopant: A doping agent used to alter electrical properties. One layer of a PV cell is diffused with a negative tendency (“n-layer”) dopant such as phorphorous while another layer is diffused with a positive tendency (“p-layer”) dopant such as boron. Dopants create an electrical field to motivate electrons when light strikes the PV cell.

Electricity Measurement: The following are typical measurements and formulas.

Electron Flow: Flow through wire depends on electrical pressure pushing electrons.

Energy: Can exist in a variety of forms, such as electrical, mechanical, chemical, thermal, or nuclear, and can be transformed from one form to another. It is measured by the amount of work done, usually in joules or watts.

Federal Land Policy and Management Act of 1976: States that the Bureau of Land Management (BLM) manages public lands for multiple uses. Charters the BLM with balancing the needs of many people AND protecting the land and resources.

Fossil Fuels: Any combustible organic material, as oil, coal, or natural gas, derived from the remains of former life. Made up of hydrocarbon molecules.

Gamma Rays: Transformed into visible light when they reach sun’s surface (photosphere).

Greenhouse Gasses: Any of the atmospheric gases that contribute to the greenhouse effect by absorbing infrared radiation produced by solar warming of the Earth's surface.

Grid-Connected PV System: Photovoltaic (PV) system that operates in parallel and interconnected with national utility grid. Primary component—inverter or power conditioning unit (PCU) that converts DC into AC power. No battery storage is needed.

Heat Energy: Not transmitted from sun (because space between sun an Earth is a vacuum). Radiant energy transforms into thermal (heat) energy when it strikes molecules in the atmosphere or on Earth’s surface.

Hydrosphere: The oceans or masses of water on Earth. Carbon dioxide molecules are produced from the ocean through photosynthesis.

Inverter: (see Power Inverter)

Land Use Plan: Detailed guide prepared by the Bureau of Land Management (BLM) that explains what activities are allowed on public land. Describes how activities are managed and monitored. Meets all governing laws and regulations.

Light Consumption

Light Quality

Light Quantity

Lighting

Lithosphere: Rigid outermost shell of Earth (or any planet). Fossil fuels are found in the lithosphere.

Load: Something that uses electricity. Any device placed in a circuit to do work. Every load has resistance.

Lumen (lm): Unit of luminous power (flux); a measure of the total “amount” of visible light emitted by a source. (see also Luminous Power and Radiant Power)

Luminous Power (or Luminous Flux): Measurement of the perceived power of light. Measurements reflect the varying sensitivity of the human eye to different wavelengths of light. (see also Lumen and Radiant Power)

National Environmental Policy Act: Protection of environment became national goal.

Nonrenewable Resource: A natural resource which cannot be produced, regrown, regenerated, or reused on a scale which can sustain its consumption rate. Examples are coal, petroleum/oil, and natural gas.

Nuclear Fusion: A process in which the sun uses gases and makes energy in its inner core. During nuclear fusion, high pressure and temperature force hydrogen (H) atoms to come apart and produce radiant—solar—energy. Nuclear fusion produces gamma rays which are constantly and re-emitted. (see also Gamma Rays and Radiant Energy)

Passive Solar: Use of solar energy (such as for radiant heat) that does not require mechanical equipment. The building acts as a solar collector.

Photons: Bundles of radiant energy. Photons strike a PV cell and may be reflected, absorbed, or transmitted through the cell. Only absorbed photons generate electricity.

Photosphere: Visible surface of the sun.

Photosynthesis: (in plants) The synthesis of organic compounds from carbon dioxide and water (with the release of oxygen) using light energy absorbed by chlorophyll.

Photovoltaic (PV): (photo means light, volt is a measurement of electricity) PV cells generate electricity directly from electrons freed by the interaction of radiant energy with the semiconductor materials in the PV cells. Residential PV system offsets power usage at an individual home. Commercial PV system is designed to offset power usage at a business or industrial site. Utility PV system is employed by energy companies to produce base-load or peak-load power for sale to consumers. (see also Grid-Connected PV System, Standalone PV System, and Photovoltaic Technology)

Photovoltaic Effect: Basic physical process through which a PV cell converts sunlight directly into electricity. More electricity when light is more intense, when light strikes PV modules directly.

Photovoltaic Technology: The following is a summary of how a PV cell is made.

Power Inverter: Converts DC current (current flows in single direction) to AC current (flow reverses direction at intervals). AC is used by most appliances/devices.

Radiant Energy (Solar Energy): Produced during nuclear fusion in the sun when four hydrogen (H) nuclei (centers of the atoms) fuse to form one helium (He) atom. Matter converts to energy during nuclear fusion. Converted matter is emitted into space as radiant energy. 15% is reflected back into space, 30% powers the water cycle (evaporation–condensation–precipitation), and some energy is absorbed by plants, land, oceans. The rest is reflected and can be used to supply our energy needs.

Radiant Power (Radiant Flux): Measurement of the total power of light emitted, independent of the eye’s ability to perceive it. (see also Lumen and Luminous Flux)

Renewable Resource: Any natural resource that can be replenished naturally with the passage of time. Examples are solar, wind, hydro, geothermal, and biomass.

Solar Collector: Captures sunlight and changes it into heat energy that can be trapped, stored, and used.

Solar Electriciy: Electricity produced by solar energy. Two types are concentrated solar power (CSP) and photovoltaics. (see also Concentrated Solar Power and Photovoltaics)

Solar Energy: Energy derived from the sun in the form of solar radiation.

Solar Panel: A panel that, when exposed to radiation from the sun, is used to heat water. When mounted with solar cells, it is used to produce electricity directly.

Solar Space Heating: Heating the inside of a building using solar energy. Two types are passive solar and active solar. (see also Passive Solar and Active Solar)

Solar Water Heating: Active system that collects sunlight and converts it to heat. Pump circulates water through collector until it reaches desired temperature (the set point). Water is pumped to storage tank where it is used in a heat exchanger to heat water. (see also Passive Solar and Active Solar)

Standalone PV System: Photovoltaic (PV) system that is independent of national electric utility grid. Supplies electricity to a single system. Includes one or more batteries to store electricity. Used for water pumping, highway lighting, weather stations, remote homes, areas away from power lines.

Sun: A ball of gar made up mostly of hydrogen (H) and helium (He) atoms.

Sustainable Energy: The provision of energy such that it meets the needs of the present without compromising the ability of future generations to meet their needs.