Glossary & Acronyms

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AC- Alternating current
Alternating Current or AC electricity is a back-and-forth movement of electrons in a wire, similar to sloshing water back-and-forth in a hose. When the force of a negative (-) charge is at one end of a wire and a positive (+) potential is at the other end, the electrons in the wire will move away from the (-) charge, just like in DC electricity. But if the charges at the ends of the wires are suddenly switched, the electrons will reverse their direction. (see also DC- Direct Current)

ACPI- Advanced Configuration and Power Interface
ACPI is a power management specification developed by Intel, Toshiba and Microsoft that makes hardware status information available to the operating system. ACPI enables a PC to turn its peripherals on and off for improved power management especially in portables. It also allows the PC to be turned on and off by external devices, so that the touch of a mouse or the press of a key will "wake up" the machine.

AP- Access Point
Short for Access Point, a hardware device or a computer's software that acts as a communication hub for users of a wireless device to connect to a wired LAN. APs are important for providing heightened wireless security and for extending the physical range of service a wireless user has access to.

APM- Advanced Power Management
APM is an API (Application Program Interface) developed by Intel and Microsoft that allows developers to include power management in BIOSes.For more information on the different power saving modes, such as Ready, Standby, Suspended, Hibernation, and Off, see Description of the Different Advanced Power Management States (Microsoft Support web site)

BD- Biodiesel
Biodiesel is a vegetable oil-based fuel that runs in diesel engines - cars, buses, trucks, construction equipment, boats, generators, and oil home heating units. It's usually made from soy or canola oil, and can also be made from recycled fryer oil. You can blend it with regular diesel or run 100% biodiesel.

BIOS- Basic input/output system
BIOS is the built-in software that determines what a computer can do without accessing programs from a disk. On PCs, the BIOS contains all the code required to control the keyboard, display screen, disk drives, serial communications, and a number of miscellaneous functions.

BOS- Balance of systems
In a renewable energy system, BOS is a quantity that refers to all components other than the mechanism used to harvest the resource (such as solar panels or a wind turbine). It includes design costs, land, site preparation, system installation, support structures, power conditioning, operation and maintenance costs, batteries, indirect storage, and related costs.

CFL- Compact Fluorescent Lights
CFLs use less energy than standard lights. The typical CFL bulb consumes only about 25 percent of the electricity required by standard bulbs.

COE- Cost of electricityThe cost of electricity (COE) is comprised of three components: capital and installation (C&I), operation and maintenance (O&M), and fuel (F). The total cost of electricity from a DER device is the sum of these three components, expressed in dollars (or cents) per kilowatt-hour: Total COE ($/kWh) = C&I + O&M + F.

CPU- Central Processing Unit.
The main computational section of a computer that interprets and executes instructions. The CPU of a desktop computer can consume as much as 80 W. The overal energy consumption of a computer is mostly a function of the CPU and the screen technologies.

CRT- Cathode ray tube
CRT is the technology behind most television sets and computer display screens used to accompany desktop computers. See also LCD)

DC- Direct current
DC electricity is a direct flow of electrons through a conductor such as a metal wire. A battery or DC generator usually provides a source of electrons and the potential or voltage between the positive (+) and negative (-) terminals. This flow of electrons through a wire can be thought of as similar to the constant flow of water through a hose. (See also AC- Alternating Current)

ELC- Electronic Load Controller

EPA- Environmental Protection Agency (US)
EPA Web site:

GHG- Green House Gases
Greenhouse gases (GHG) are gaseous components of the atmosphere that contribute to the greenhouse effect. The major natural greenhouse gases are water vapor, which in the cloudless case causes (see note below) about 60-70% of the greenhouse effect on Earth, carbon dioxide (about 26%) and ozone.

Grid- When used in reference to utility power, it refers to a system of electrical transmission and distribution lines.

HDPE- High Density Polyethylene
HDPE is the plastic commonly used to make milk and water jugs and two liter soda bottle bases.

HF- High Frequency
High-frequency; any radio frequency in the 3,000- to 30,000-kHz range.

ICT- Information and Communication Technology
ICT refers to both computer and communication technology. IT (or information technology) is defined as any equipment or interconnected system (subsystem) of equipment that includes all forms of technology used to create, store, manipulate, manage, move, display, switch, interchange, transmit or receive information in its various forms. Information can be in the form of: business data; voice conversations; still images; motion pictures; multimedia presentations and other forms including those not yet conceived. The meaning of communication refers to a system of shared symbols and meanings that binds people together into a group, a community, or a culture. The word communication was added to IT so as to make a network of the usage of Information Technology.

IEEE- Institute of Electrical and Electronics Engineers
Professional organization whose activities include the development of communications and network standards. IEEE LAN standards are the predominant LAN standards today.

Inverters convert DC electricity that is stored in batteries to AC electricity that is used in common household appliances.

ISP- Internet Service Provider
An ISP provides access to the Internet for others via some connectivity service(s). This might be in the form of dial up services, web hosting services or the combination of both

ITU International Telecommunication Union
The ITU, headquartered in Geneva, Switzerland is an international organization within the United Nations System where governments and the private sector coordinate global telecom networks and services. ITU web site:

LAN- Local Area Network
A LAN is a local computer network for communication between computers; especially a network connecting computers and word processors and other electronic office equipment to create a communication system between offices.

LCD Monitor
A screen for displaying text/graphics based on a technology called liquid crystal, where minute currents change the reflectiveness or transparency of the screen. The advantages of LCD screens are: very small power consumption (can be easily battery driven) and low price of mass produced units. Its disadvantages presently include narrow viewing angle, somewhat slower response time, invisibility in the dark unless the display is back-lit, difficulties displaying true colors and resolution limitations. (see also CRT)

LED- Light Emitting Diode
A small indicator light most often used to show the power is on or the device is being used. LEDs are found on your computer case, monitor, printer, modem, CD-ROM drive, and hard drive.

Life Cycle Cost (LCC): The cost of a good or service over its entire life cycle.

LMR- Land Mobile Radio
(also called "trunked radio")

LOS - Line of Sight
This term is often associated with radio transmission systems indicating there is a clear path between the transmitter and receiver. An example of a communication system that requires a Line Of Sight is a microwave link.

LTSP - Linux Terminal Server Program

There is no universally accepted definition of the size of micro-hydro vs. pico-hydro systems. The most common convention is to label systems under 100 kW as micro-hydro. Pico-hydro are often considered to be under 1 kW. Knowing the prevailing definition of micro- and pico-hydro can be important because in some countries, these designations have implications for local laws and regulations.

NPC - Net Present Cost

NTC - Negative Thermal Coefficient

Off Grid - An electrical system that is not connected to a utility distribution grid.

O&M - Operation and Maintenance

OS - Operating System
The basic software that makes a computer run. An OS schedules tasks, allocates storage, handles the interface to peripheral hardware and presents a default interface to the user when no application program is running.

PDA- Personal Digital Assistant

Photovoltaic (or PV)
Photovoltaic (or PV) systems convert sun light energy into electricity. Photovoltaic systems typically have four principal components: solar panels, (modules), an energy storage device (battery), a charge and consumption controller, and an inverter. Since solar panels produce direct current (DC) and most conventional equipment operates on alternating current (AC), the inverter is used to change the DC current to AC current. The energy is then stored for use during overcast periods and at night. It can be stored as chemical energy in batteries, or as potential energy in pumped water tanks.

PSH - Peak Sun Hours
The intensity of the Sun's radiation changes with the hour of the day, time of the year and weather conditions. To be able to make calculations in planning a system, the total amount of solar radiation energy is expressed in hours of full sunlight per mē, or Peak Sun Hours. This term, Peak Sun Hours, represents the average amount of sun available per day throughout the year.
See Glossary of Related Solar Power Terms at

PVC - Polyvinyl Chloride

RAM - Random Access Memory

RE - Renewable Energy
Energy obtained from sources that are essentially inexhaustible (unlike, for example, the fossil fuels, of which there is a finite supply). Renewable sources of energy include wood, waste, geothermal, wind, photovoltaic, and solar thermal energy.

SME- Small and medium enterprises

Spread Spectrum
A method of transmitting a signal by "spreading" it over a broad range of frequencies (using a compatible receiver to reassemble the signal). This provides reduced interference (see "processing gain") and can increase the number of simultaneous users within a radio frequency band.

TFT - Thin Film Transistor
Thin Film Transistor LCD panel. A type of LCD flat panel display screen in which each pixel is controlled by one to four transistors. The TFT technology provides the best resolution of all the flat panel techniques, but it is also the most expensive. TFT screens are sometimes called active matrix LCDs.

UHF - Ultra high frequency
UF refers to any radio frequency in the 300- to 3,000-MHz range.

UNEP - United Nations Environmental Programme
Headquartered in Nairobi, Kenya, the UN Environment Programme (UNEP) coordinates United Nations environmental activities, assisting developing countries in implementing environmentally sound policies and to encourage sustainable development through sound environmental practices. UNEP web site:

UPS - Uninterruptible power supply
UPS is primarily used as a back up power source for computers and computer networks to insure on-going operation in the event of a power failure. Sophisticated units also have power conditioning and power monitoring features.

USAID - United States Agency for International Development
The United States government agency responsible for administering development assistance around the world. USAID Web site:

VCR - Video Cassette Recorder

VHF- Very High Frequency
VHF refers to any radio frequency in the 30- to 300-MHz range.

WiFi -Wireless Fidelity
Wi-Fi (or Wi-fi, WiFi, Wifi, wifi), short for "Wireless Fidelity", is a set of standards for wireless local area networks (WLAN) currently based on the IEEE 802.11 specifications.

WISP - Wireless internet service provider
WISP is an acronym which stands for Wireless Internet Service Provider. These can be Wi-Fi hotspots or an operator with a Wi-Fi based network infrastructure. Often they offer additional services, like location based content, Virtual Private Networking and Voice over IP.

VSAT - Very Small Aperture Terminal
Very Small Aperture Terminal. An earth station, used for the reliable transmission of data, video, or voice via geo-stationary satellite, with a relatively small dish-antenna (often 2.4m or 3.8m in diameter).

Glossary of Energy Terms (US Dept. of Energy)