Glossary

Renewable Energy Terms & Phrases

Solar Energy – energy that comes from the sun that can be used to generate electricity, heat water, heat a building, etc.
Photovoltaic (PV) Cells – convert sunlight directly into electricity
Net Metering – allows PV customers to sell excess electricity back into the grid
Concentrating Solar Power – uses mirrors to focus the sun’s energy into high-temperature heat which is used to generate electricity in a steam generator
Solar Thermal – uses the sun’s rays to heat water
Daylighting – using sunlight to illuminate a building
Passive Solar – using sunlight to generate heat, often for heating a building
Wind Power – using wind to move a turbine to generate electricity
Biofuels – using recently living organisms like corn, soybean, and other plants to derive energy, often used to fuel vehicles

Glossary of Alternative Energy Terms

Alternating Current (AC): the type of electricity used by most household appliances. An inverter is used in a renewable energy system to convert incoming direct current (DC) into usable alternating current (AC).
Carbon dioxide (CO2): greenhouse gas linked to global warming.
Charge controller: component of a photovoltaic system that controls the flow of current to and from the battery to regulate the flow to prevent over-charge or over-discharge.
Compact fluorescent lighting (CFL): an energy-efficient form of lighting. CFL bulbs use one quarter to one-third as much electricity to provide the same light output as a standard incandescent bulb while creating much less heat, and they last up to 10 times as long as a standard incandescent bulb (10,000 vs. 1,000 hours).
Conversion efficiency (%): the percentage of the sunlight incident on a solar panel that is successfully passed to the system as current.
Critical load sub-panel: a secondary load circuit used with a backup power system to isolate the circuits that will receive power from the backup power source.
Direct current (DC): the form of electricity generated by renewable sources.
Disconnect: switch used to turn on or off current between various components of a renewable energy system.
Energy efficiency: technologies and measures that reduce the amount of electricity and/or fuel required to do the same work without reducing the end-use benefits.
Energy management: empowering a customer to monitor and control usage to leverage use with times of peak pricing or demand. Allows visibility into usage and opportunities for conservation measures.
Fossil fuel: examples are oil, coal, and natural gas. Finite resources formed in the ground millions of years ago from plant and animal remains. Fossil fuels are the primary source of power generation. The process of burning fossil fuels produces emissions that are detrimental to the environment, such as carbon dioxide (CO2), nitrous oxides (NOx), and sulfurdioxide (SO2). These emissions are one of the leading causes of global warming, pollution, smog, acid rain, and other negative health effects that result from poor air quality.
Insulation: the amount of solar power incurred by a surface of a specific area and orientation. Typically expressed as watts per square meter per day.
Interconnection: an agreement made with a utility provider to establish a grid-tied renewable energy system. Allows for energy to flow in both directions from the system.
Inverter: a device that converts direct current (DC) into alternating current (AC).
Junction box: in reference to a solar PV module, an enclosure located on the back of the module where PV strings are electrically connected and protection devices are located.
Kilowatt (kW): standard unit of electrical power equal to 1,000 watts (kilo = 1,000).
Kilowatt-hour (kWh): standard measurement of electricity consumption or production. One thousand watts consumed or produced over the course of one hour. For example, a 100-watt light bulb used for 10 hours would consume 1 kWh of electricity.
Load: the electrical demand of a location. Also, the amount of energy required by a particular piece of equipment. Usually expressed in watts or kilowatts.
Load circuit (electrical panel): the combined wires, switches, fuses, etc. that connect the load to the power source.
Megawatt (MW): 1,000 kilowatts or 1 million watts.(Mega = million). Standard measure of electrical generation capacity at utility-scale facilities.
Megawatt-hour (MWh): 1 megawatt used or produced over the course of one hour.
Nitrogen oxides (NOx): 22% of the nitrogen oxide pollution in the United States comes from power production. Nitrogen oxides are one of the main ingredients in the formation of ozone and smog. It also contributes to the formation of acid rain and global warming.
Orientation: siting of photovoltaic panels in relation to the cardinal directions (north, south, east, west). South is the optimal orientation in the northern hemisphere, although good production can be realized with panels facing east and west.
Peak demand: the maximum energy demand during particular time period.
Photovoltaic (PV) effect: “photo” = light; “voltaic” =electricity. The process by which photons from the sun’s rays knock electrons loose from the atoms that they strike.
Photovoltaic (PV) array: the combination of multiple PV panels (modules) that function as a single electricity-producing unit.
Photovoltaic (PV) cell: the smallest building block of the solar electrical system. Composed of semiconductor material. Performs the immediate conversion of light into electrical energy in the form of direct current (DC).
Photovoltaic (PV) module/panel: the combination of multiple PV cells laminated between thick sheets of tempered glass, which is then placed in a frame for support. Module production ratings are based on the sum of the production capacity of the cells in the module and typically range from 30 to 300 watts.
Renewable Energy Certificate (REC): also known as green certificates’ or green tags. Tradable commodity usually measured in 1MWh (megawatt-hour) of energy from a renewable source. Sold separately from commodity electricity.
Renewable Portfolio Standard (RPS): policy set by federal or state governments requiring that a certain percentage of the area’s electricity come from renewable sources.
Semiconductor: any material that has limited ability to conduct an electric current. The most common semiconductor used in photovoltaic applications is silicon. Other semiconductors used for photovoltaic applications include cadmium telluride, copper indium diselenide, and gallium arsenide.
Solar resource: amount of solar insulation a site receives, measured in kilowatt-hours per square meter per day. Equivalent tithe number of peak sun hours.
SO2 (sulfur dioxide): 67% of the sulfur dioxide emissions produced in the United States are from power generation. Sulfur dioxide emissions are one of the main contributors to the production of acid rain.
Standard Test Conditions (STC): controlled conditions under which PV modules are tested in a laboratory. Output rating oaf module is typically based on output measured when subjected to these conditions.
Watt: unit of measure of electricity. The product of voltage and current.
Wind turbine: device that uses wind energy to generate electricity.