Alternating Current (AC): Electric current that reverses direction 50 or 60 times per second depending on the country.Amp: A measure of the quantity of electricity flowing in a circuit.Amp-hour: Measure of the amount of electrical current flowing for a period of time.Biodiesel: An alternative fuel produced from renewable resources such as plant oils, animal fats, used cooking oil, and new sources such as algae. Biodiesel contains no petroleum, but can be combined in any quantity with petroleum diesel to create a biodiesel blend.Biomass: Refers to biological materials that were alive or created during our lifetimes and specifically excludes coal and petroleum. Biomass energy uses natural materials like trees and plants.Direct Current Electricity (DC): Electricity that flows only in one direction. Direct Current is the type of electricity supplied by batteries.EV: An abbreviation for an electric vehicle.Feed-in-Tariff (FIT) Money paid to a customer by a power company for excess electricity generated by a renewable energy source. The renewable energy source is most often either solar or wind generated electricity. This excess is connected to the power lines at the customer’s residence, and most commonly on the customer’s side of the electric meter.Geothermal: Heat from the earth, often thought of as energy from geysers and hot springs. More recently, this term is applied to any heat stored in earth and available as a renewable energy resource.Gigawatt: One billion watts of electrical energy.Global Warming: The Earth’s gradual warming due to the greenhouse effect.Greenhouse Effect: The rise in temperature the Earth experiences because certain gases in the atmosphere (such as water vapor, carbon dioxide, nitrous oxide, and methane) trap energy from the sun.Greenhouse Gases: Gases in the Earth’s atmosphere that produce the greenhouse effect. Changes in the concentration of certain greenhouse gases, due to human activity such as fossil fuel burning, increase the risk of global climate change. Greenhouse gases include water vapor, carbon dioxide, methane, nitrous oxide, ozone, and various forms of fluorocarbon gas (used in air conditioners and refrigerators).Grid: The network of wires and cables that transport electricity from a power plant to your home.HERS: an abbreviation for Home Energy Rating System which provides a standardized evaluation of a home’s energy efficiency and expected energy costs.Inverter: An electrical device that changes direct current (DC) into alternating current (AC).Kilowatt (kW): One thousand watts of electricityKilowatt-hour (kW-h): One thousand watt-hours. Calculated by multiplying the number of watts being used times the length of time in hours that amount of electricity is used.LEED: Abbreviation for Leadership in Energy and Environmental Design.Light Emitting Diode (LED): An extremely efficient source of light, LED lamps convert from 65 to 95 of the electric energy to light energy (depending on the color of the light) and typically last 50,000 to 100,000 hours. Light emitting diodes are made from the same material as transistors and give off light when electricity is passed through them.Megawatt: One million watts of electrical energy.Net Metering: A contractual arrangement that permits an electrical utility customer to turn their electric meter backwards and sell any excess power generated (over and above their usage requirement) back to the electrical grid to offset their consumption.Off-the-grid (Off-grid): Not connected to the commercial power lines.Photovoltaic (PV): Light-generated voltagePhotovoltaic (PV) Cell: An electronic device consisting of layers of special materials capable of converting light directly into electricity.Photovoltaic (PV) Module: An assembly of interconnected photovoltaic cells enclosed in a protective assembly (usually glass and plastic).Renewable Electricity: Renewable electricity is electricity generated without use of fossil fuels.Renewable Energy (RE): An energy source that renews itself without effort. Fossil fuels, once consumed, are gone forever, while solar energy is renewable in that the sun energy we harvest today has no effect on the sun energy we can harvest tomorrow.Solar Cell: A device made of silicon and other materials. Solar cells generate electricity when exposed to sunlight.Solar Energy: The radiant energy of the sun, which can be converted into other forms of energy such as heat or electricity.Sustainable: Frequently used as meaning to not take more from a resource than is replenished naturally.Thermal Solar: The process of deriving or concentrating heat from sunlight.Tracker: Mechanical device used in solar electric and solar thermal systems. Follows the movement of the sun (daily and sometimes seasonally) and keeps the energy collection device pointed directly at the sun, thereby allowing the maximum available solar energy.Uninterruptible Power Supply (UPS): A device (usually containing batteries) that stores power for use when conventional power is unavailable, such as during a power failure.Volt: Unit of electrical pressure.Watt: Unit of electrical power that is calculated by multiplying the electrical pressure in a circuit by the amount of electricity moving in the circuit.Wind Turbine: Devices consisting of blades that turn a shaft that turns a generator to harvest wind energy and produce electrical power.