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Energy.gov - Energy industry terms Category: Earth and Environment > Energy industry terms Date & country: 26/02/2017, USA Words: 1299

Solstice
The two times of the year when the sun is apparently farthest north and south of the earth's equator; usually occurring on or around June 21 (summer solstice in northern hemisphere, winter solstice for southern hemisphere) and December 21 (winter solstice in northern hemisphere, summer solstice for the southern hemisphere).

Space Heater
A movable or fixed heater used to heat individual rooms.

Spacer
(Window) Strips of material used to separate multiple panes of glass within the windows.

Solenoid Valve
An automatic valve that is opened or closed by an electromagnet.

Solid Fuels
Any fuel that is in solid form, such as wood, peat, lignite, coal, and manufactured fuels such as pulverized coal, coke, charcoal, briquettes, pellets, etc.

Solidity
In reference to a wind energy conversion device, the ratio of rotor blade surface area to the frontal, swept area that the rotor passes through.

Solar Two
Solar Two is a retrofit of the Solar One project (see above). It is demonstrating the technical feasibility and power potential of a solar power tower using advanced molten-salt technology to store energy. Solar Two retains several of the main components of Solar One, including the receiver tower, turbine, generator, and the 1,818 heliostats.

Solenoid
An electromechanical device composed of a coil of wire wound around a cylinder containing a bar or plunger, that when a current is applied to the coil, the electromotive force causes the plunger to move; a series of coils or wires used to produce a magnetic field.

Solar Transmittance
The amount of solar energy that passes through a glazing material, expressed as a percentage.

Solar Thermal Systems
Solar energy systems that collect or absorb solar energy for useful purposes. Can be used to generate high temperature heat (for electricity production and/or process heat), medium temperature heat (for process and space/water heating and electricity generation), and low temperature heat (for water and space heating and cooling).

Solar Time
The period marked by successive crossing of the earth's meridian by the sun; the hour angle of the sun at a point of observance (apparent time) is corrected to true (solar) time by taking into account the variation in the earth's orbit and rate of rotation. Solar time and local standard time are usually different for any specific location.

Solar Thermal Parabolic Dishes
A solar thermal technology that uses a modular mirror system that approximates a parabola and incorporates two-axis tracking to focus the sunlight onto receivers located at the focal point of each dish. The mirror system typically is made from a number of mirror facets, either glass or polymer mirror, or can consist of a single stretched membrane using a polymer mirror. The concentrated sunlight may be used directly by a Stirling, Rankine, or Brayton cycle heat engine at the focal point of the receiver or to heat a working fluid that is piped to a central engine. The primary applications include remote electrification, water pumping, and grid-connected generation.

Solar Spectrum
The total distribution of electromagnetic radiation emanating from the sun. The different regions of the solar spectrum are described by their wavelength range. The visible region extends from about 390 to 780 nanometers (a nanometer is one billionth of one meter). About 99 percent of solar radiation is contained in a wavelength region from 300 nm (ultraviolet) to 3,000 nm (near-infrared). The combined radiation in the wavelength region from 280 nm to 4,000 nm is called the broadband, or total, solar radiation.

Solar Thermal Electric Systems
Solar energy conversion technologies that convert solar energy to electricity, by heating a working fluid to power a turbine that drives a generator. Examples of these systems include central receiver systems, parabolic dish, and solar trough.

Solar Simulator
An apparatus that replicates the solar spectrum, and used for testing solar energy conversion devices.

Solar Space Heater
A solar energy system designed to provide heat to individual rooms in a building.

Solar Power Satellite
A solar power station investigated by NASA that entailed a satellite in geosynchronous orbit that would consist of a very large array of solar photovoltaic modules that would convert solar generated electricity to microwaves and beam them to a fixed point on the earth.

Solar Radiation
A general term for the visible and near visible (ultraviolet and near-infrared) electromagnetic radiation that is emitted by the sun. It has a spectral, or wavelength, distribution that corresponds to different energy levels; short wavelength radiation has a higher energy than long-wavelength radiation.

Solar Module
(Panel) A solar photovoltaic device that produces a specified power output under defined test conditions, usually composed of groups of solar cells connected in series, in parallel, or in series-parallel combinations.

Solar Noon
The time of the day, at a specific location, when the sun reaches its highest, apparent point in the sky; equal to true or due, geographic south.

Solar Pond
A body of water that contains brackish (highly saline) water that forms layers of differing salinity (stratifies) that absorb and trap solar energy. Solar ponds can be used to provide heat for industrial or agricultural processes, building heating and cooling, and to generate electricity.

Solar Mass
A term used for materials used to absorb and store solar energy.

Solar Irradiation
The amount of solar radiation, both direct and diffuse, received at any location.

Solar Furnace
A device that achieves very high temperatures by the use of reflectors to focus and concentrate sunlight onto a small receiver.

Solar Gain
The amount of energy that a building absorbs due to solar energy striking its exterior and conducting to the interior or passing through windows and being absorbed by materials in the building.

Solar Energy Research Institute
(SERI) A federally funded institute, created by the Solar Energy Research, Development and Demonstration Act of 1974, that conducted research and development of solar energy technologies. Became the National Renewable Energy Laboratory (NREL) in 1991.

Solar Film
A window glazing coating, usually tinted bronze or gray, used to reduce building cooling loads, glare, and fabric fading.

Solar Fraction
The percentage of a building's seasonal energy requirements that can be met by a solar energy device(s) or system(s).

Solar Distillation
The process of distilling (purifying) water using solar energy. Water can be placed in an air tight solar collector with a sloped glazing material, and as it heats and evaporates, distilled water condenses on the collector glazing, and runs down where it can be collected in a tray.

Solar Energy
Electromagnetic energy transmitted from the sun (solar radiation). The amount that reaches the earth is equal to one billionth of total solar energy generated, or the equivalent of about 420 trillion kilowatt-hours.

Solar Energy Industries Association
(SEIA) A national trade association of solar energy equipment manufacturers, retailers, suppliers, installers, and consultants.

Solar Declination
The apparent angle of the sun north or south of the earth's equatorial plane. The earth's rotation on its axis causes a daily change in the declination.

Solar Array
A group of solar collectors or solar modules connected together.

Solar Azimuth
The angle between the sun's apparent position in the sky and true south, as measured on a horizontal plane.

Solar Cell
A solar photovoltaic device with a specified area.

Solar Constant
The average amount of solar radiation that reaches the earth's upper atmosphere on a surface perpendicular to the sun's rays; equal to 1353 Watts per square meter or 492 Btu per square foot.

Solar Air Heater
A type of solar thermal system where air is heated in a collector and either transferred directly to the interior space or to a storage medium, such as a rock bin.

Solar Altitude Angle
The angle between a line from a point on the earth's surface to the center of the solar disc, and a line extending horizontally from the point.

Sodium Lights
A type of high intensity discharge light that has the most lumens per watt of any light source.

Soffit
A panel which covers the underside of an roof overhang, cantilever, or mansard.

Solar Access or Rights
The legal issues related to protecting or ensuring access to sunlight to operate a solar energy system, or use solar energy for heating and cooling.

Smart Window
A term used to describe a technologically advanced window system that contains glazing that can change or switch its optical qualities when a low voltage electrical signal is applied to it, or in response to changes in heat or light.

Skylight
A window located on the roof of a structure to provide interior building spaces with natural daylight, warmth, and ventilation.

Slab
A concrete pad that sits on gravel or crushed rock, well-compacted soil either level with the ground or above the ground.

Slab on Grade
A slab floor that sits directly on top of the surrounding ground.

Single-Phase
A generator with a single armature coil, which may have many turns and the alternating current output consists of a succession of cycles.

Sizing
The process of designing a solar system to meet a specified load given the solar resource and the nominal or rated energy output of the solar energy collection or conversion device.

Single-Crystal Material
In reference to solar photovoltaic devices, a material that is composed of a single crystal or a few large crystals.

Single-Package System
A year 'round heating and air conditioning system that has all the components completely encased in one unit outside the home. Proper matching of components can mean more energy-efficient operation compared to components purchased separately.

Single Glaze or Pane
One layer of glass in a window frame. It has very little insulating value (R-1) and provides only a thin barrier to the outside and can account for considerable heat loss and gain.

Sine Wave
The type of alternative current generated by alternating current generators, rotary inverters, and solid-state inverters.

Siding
A construction element applied to the outermost surface of an exterior wall.

Sigma Heat
The sum of sensible heat and latent heat in a substance above a base temperature, typically 32 degrees Fahrenheit.

Silicon
A chemical element, of atomic number 14, that is semi-metallic, and an excellent semiconductor material used in solar photovoltaic devices; commonly found in sand.

Simple CS
(Caulk and Seal) A technique for insulating and sealing exterior walls that reduces vapor diffusion through air leakage points by installing pre-cut blocks of rigid foam insulation over floor joists, sheet subfloor, and top plates before drywall is installed.

Shutter
An interior or exterior movable panel that operates on hinges or slides into place, used to protect windows or provide privacy.

Short Circuit Current
The current flowing freely through an external circuit that has no load or resistance; the maximum current possible.

Short Circuit
An electric current taking a shorter or different path than intended.

Sheathing
A construction element used to cover the exterior of wall framing and roof trusses.

Shading Coefficient
A measure of window glazing performance that is the ratio of the total solar heat gain through a specific window to the total solar heat gain through a single sheet of double-strength glass under the same set of conditions; expressed as a number between 0 and 1.

Setback Thermostat
A thermostat that can be set to automatically lower temperatures in an unoccupied house and raise them again before the occupant returns.

Series Resistance
Parasitic resistance to current flow in a cell due to mechanisms such as resistance from the bulk of the semiconductor material, metallic contacts, and interconnections.

Sensible Heat Storage
A heat storage system that uses a heat storage medium, and where the additional or removal of heat results in a change in temperature.

Series
A configuration of an electrical circuit in which the positive lead is connected to the negative lead of another energy producing, conducting, or consuming device. The voltages of each device are additive, whereas the current is not.

Series Connection
A way of joining photovoltaic cells by connecting positive leads to negative leads; such a configuration increases the voltage.

Sensible Heat
The heat absorbed or released when a substance undergoes a change in temperature.

Sensible Cooling Load
The interior heat gain due to heat conduction, convection, and radiation from the exterior into the interior, and from occupants and appliances.

Semiconductor
Any material that has a limited capacity for conducting an electric current. Certain semiconductors, including silicon, gallium arsenide, copper indium diselenide, and cadmium telluride, are uniquely suited to the photovoltaic conversion process.

Sensible Cooling Effect
The difference between the total cooling effect and the dehumidifying effect.

Seebeck Effect
The generation of an electric current, when two conductors of different metals are joined at their ends to form a circuit, with the two junctions kept at different temperatures.

Selective Absorber
A solar absorber surface that has high absorbence at wavelengths corresponding to that of the solar spectrum and low emittance in the infrared range.

Selective Surface Coating
A material with high absorbence and low emittance properties applied to or on solar absorber surfaces.

Seasoned Wood
Wood, used for fuel, that has been air dried so that it contains 15 to 20 percent moisture content (wet basis).

Second Law Efficiency
The ratio of the minimum amount of work or energy required to perform a task to the amount actually used.

Second Law of Thermodynamics
This law states that no device can completely and continuously transform all of the energy supplied to it into useful energy.

Seasonal Performance Factor
(SPF) Ratio of useful energy output of a device to the energy input, averaged over an entire heating season.

Seasonal Energy Efficiency Ratio
(SEER) A measure of seasonal or annual efficiency of a central air conditioner or air conditioning heat pump. It takes into account the variations in temperature that can occur within a season and is the average number of Btu of cooling delivered for every watt-hour of electricity used by the heat pump over a cooling season.

Scribing
The cutting of a grid pattern of grooves in a semiconductor material, generally for the purpose of making interconnections.

Sealed Combustion Heating System
A heating system that uses only outside air for combustion and vents combustion gases directly to the outdoors. These systems are less likely to backdraft and to negatively affect indoor air quality.

Safety Disconnect
An electronic (automatic or manual) switch that disconnects one circuit from another circuit. These are used to isolate power generation or storage equipment from conditions such as voltage spikes or surges, thus avoiding potential damage to equipment.

Salt Gradient Solar Ponds
Consist of three main layers. The top layer is near ambient and has low salt content. The bottom layer is hot, typically 160 F to 212 F (71 C to 100 C), and is very salty. The important gradient zone separates these zones. The gradient zone acts as a transparent insulator, permitting the sunlight to be trapped in the hot bottom layer (from which useful heat is withdrawn). This is because the salt gradient, which increases the brine density with depth, counteracts the buoyancy effect of the warmer water below (which would otherwise rise to the surface and lose its heat to the air). An organic Rankine cycle engine is used to convert the thermal energy to electricity.

Sacrificial Anode
A metal rod placed in a water heater tank to protect the tank from corrosion. Anodes of aluminum, magnesium, or zinc are the more frequently metals. The anode creates a galvanic cell in which magnesium or zinc will be corroded more quickly than the metal of the tank giving the tank a negative charge and preventing corrosion.

Run-of-River Hydropower
A type of hydroelectric facility that uses the river flow with very little alteration and little or no impoundment of the water.

Rural Electrification Administration
(REA) An agency of the U.S. Dept. of Agriculture that makes loans to states and territories in the U.S. for rural electrification and the furnishing of electric energy to persons in rural areas who do not receive central station service. It also furnishes and improves electric and telephone service in rural areas, assists electric borrowers to implement energy conservation programs and on-grid and off-grid renewable energy systems, and studies the condition and progress of rural electrification.

Rotor
An electric generator consists of an armature and a field structure. The armature carries the wire loop, coil, or other windings in which the voltage is induced, whereas the field structure produces the magnetic field. In small generators, the armature is usually the rotating component (rotor) surrounded by the stationary field structure (stator). In large generators in commercial electric power plants the situation is reversed. In a wind energy conversion device, the blades and rotating components.

Roof Ventilator
A stationary or rotating vent used to ventilate attics or cathedral ceilings; usually made of galvanized steel, or polypropylene.

Rock Bin
A container that holds rock used as the thermal mass to store solar energy in a solar heating system.

Rock Wool
A type of insulation made from virgin basalt, an igneous rock, and spun into loose fill or a batt. It is fire resistant and helps with soundproofing.

Roof
A building element that provides protection against the sun, wind, and precipitation.

Roof Pond
A solar energy collection device consisting of containers of water located on a roof that absorb solar energy during the day so that the heat can be used at night or that cools a building by evaporation at night.

Ribbon (Photovoltaic) Cells
A type of solar photovoltaic device made in a continuous process of pulling material from a molten bath of photovoltaic material, such as silicon, to form a thin sheet of material.

Rigid Insulation Board
An insulation product made of a fibrous material or plastic foams, pressed or extruded into board-like forms. It provides thermal and acoustical insulation strength with low weight, and coverage with few heat loss paths.

Reversing Valve
A component of a heat pump that reverses the refrigerant's direction of flow, allowing the heat pump to switch from cooling to heating or heating to cooling.

Reverse Thermosiphoning
When heat seeks to flow from a warm area (e.g., heated space) to a cooler area, such as a solar air collector at night without a reverse flow damper.

Retrofit
The process of modifying a building's structure.

Return Air
Air that is returned to a heating or cooling appliance from a heated or cooled space.

Return Duct
The central heating or cooling system contains a fan that gets its air supply through these ducts, which ideally should be installed in every room of the house. The air from a room will move towards the lower pressure of the return duct.

Resistance Heating
A type of heating system that provides heat from the resistance of an electrical current flowing through a conductor.

Resistive Voltage Drop
The voltage developed across a cell by the current flow through the resistance of the cell.

Resistor
An electrical device that resists electric current flow.