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Glossary of Therms

All 0-9 A B C D E F G H I J K L M N O P Q R S T U V W X Y Z
Word Description
Absorbent Glass Mat (AGM) A separator technology used in some sealed lead-acid batteries in which the glass-mat separator absorbs 100% of the electrolyte. Because of the immobilized electrolyte, an AGM battery will not leak or spill and does not require water addition. This battery is used in deep-cycle and specialty applications such as telecommunications, wheelchairs and security alarm systems, as well as in automotive starting applications.
Accumulator A rechargeable battery or cell (see also Secondary battery).
Acid Rain Rain or other forms of precipitation that is unusually acidic.
Actual Capacity or Available Capacity The total battery capacity, usually expressed in ampere-hours or milliampere-hours, available to perform work. The actual capacity of a particular battery is determined by a number of factors, including the cut-off voltage, discharge rate, temperature, method of charge and the age and life history of the battery.
AGM Absorbent Glass Mat - Separator technology used in some sealed lead-acid batteries in which the glass-mat separator absorbs 100% of the electrolyte. Because of the immobilized electrolyte, an AGM battery will not leak or spill and does not require water addition. This battery is used in deep-cycle and specialty applications such as telecommunications, wheelchairs and security alarm systems, as well as in automotive starting applications.
Air Gap In a permanent magnet alternator, the distance between the magnets and the laminates.
Air Pollution The modification of the natural characteristics of the atmosphere by a chemical, particulate matter, or biological agent.
Airfoil The cross section profile of the leeward side of a wind generator blade. Designed to give low drag and good lift. Also found on an airplane wing.
Alcohol Fuels Various forms of alcohol, which when blended with gasoline can be used as fuel. Common examples are methanol and ethanol.
Alternate fuels Any fuel that is not considered mainstream but may prove just as useful.
Alternating Current Electricity that changes direction periodically. The period is measured in Cycles per Second (Hertz, Hz).
Alternating Current (AC) An electric current that alternates direction between positive and negative cycles, usually 50 or 60 times per second. Alternating current is the current typically available from power outlets in a household.
Amorphous Silicon A form of silicon that is noncrystalline. Also called thin film, it is different from regular silicon used in panels and chips, in that it is more flexible. It can be deposited in thin (measured in micrometers) layers by a number of methods.
Amp Hour or Ampere-Hour A unit of measurement of a battery's electrical storage capacity. Current multiplied by time in hours equals ampere-hours. One amp hour is equal to a current of one ampere flowing for one hour. Also, 1 amp hour is equal to 1,000 mAh
Ampere A measure of electrical current. It is the number of electrons flowing past a given point in an electrical conductor in a given amount of time.
Ampere or Amp An Ampere or an Amp is a unit of measurement for an electrical current. One amp is the amount of current produced by an electromotive force of one volt acting through the resistance of one ohm. Named for the French physicist Andre Marie Ampere. The abbreviation for Amp is A but its mathematical symbol is "I". Small currents are measured in milli-Amps or thousandths of an Amp.
Ampere-Hour Capacity The number of ampere-hours which can be delivered by a battery on a single discharge.
Anemometer A device that measures wind speed.
Angle of Attack The angle of relative air flow to the blade chord.
Angle of Incidence The angle that a light ray striking a surface makes with a line perpendicular to the surface.
Annealing A heat treatment process that makes Cold-rolled steel more suitable for forming and bending.
Anode During discharge, the negative electrode of the cell is the anode. During charge, that reverses and the positive electrode of the cell is the anode. The anode gives up electrons to the load circuit and dissolves into the electrolyte.
Anti-islanding The process that prevents circuits from remaining powered after all power is cut off from the grid source.
Appliance/Equipment Efficiency Standards Many states have established minimum efficiency standards for certain appliances and equipment. In these states, the retail sale of appliances and equipment that do not meet the established standards is prohibited. The federal government has also established efficiency standards for certain appliances and equipment. When both the federal government and a state have adopted efficiency standards for the same type of appliance or equipment, the federal standard overrides the state standard (even if the state standard is stricter).
Aqueous Batteries Batteries with water-based electrolytes. The electrolyte may not appear to be liquid since it can be absorbed by the battery’s separator.
Area of a Circle Pi multiplied by the Radius squared
Armature The moving part of an alternator, generator or motor. In many PM alternator designs, it carries the magnets and is attached to the blades and hub. Also called a Rotor.
Array A collection of electrically connected photovoltaic (PV) modules.
Array Current The electrical current produced by a PV array when it is exposed to sunlight.
Array Operating Voltage The voltage produced by a PV array when exposed to sunlight and connected to a load.
Average Drain The average current withdrawn — i.e., the drain — from a cell or battery during discharge, usually approximated by calculating the current at 50% depth of discharge
Axial Alternator An alternator design where a flat disc carrying magnets on the face (the Armature) rotates near a flat disc carrying coils (the Stator).
Axis The centerline of a rotating object's movement.
Azimuth Horizontal angle measured clockwise from true north; 180° is true south.
Balancing With wind turbine blades, adjusting their weight and weight distribution through 2 axes so that all blades are the same. Unbalanced blades create damaging vibration.
Base load Minimum energy level a company provides its customers on a constant basis.
Battery An electrochemical device used to store energy. The term is usually applied to a group of two or more electric cells connected together electrically. In common usage, the term “battery” is also applied to a single cell, such as a AA battery.
Battery Capacity The electric output of a cell or battery on a service test delivered before the cell reaches a specified final electrical condition and may be expressed in ampere-hours, watt- hours, or similar units. The capacity in watt-hours is equal to the capacity in ampere-hours multiplied by the battery voltage.
Battery Cell The smallest unit or section of a battery that can store electrical energy and is capable of furnishing a current to an external load. For lead-acid batteries the voltage of a cell (fully charged) is about 2.2 volts dc.
Battery Charger A device capable of supplying electrical energy to a battery.
Battery Cycle Life The number of times a battery can be discharged and recharged before failing. Battery manufacturers specify Cycle Life as a function of discharge rate and temperature.
Battery Self-Discharge Loss of energy by a battery that is not under load.
Battery State of Charge (SOC) Percentage of full charge or 100 percent minus the depth of discharge. See Depth of Discharge.
battery terminals The parts of a battery to which the external electric circuit is connected.
Biomass Any organic material (especially trees and other vegetation) grown or produced for use as a renewable energy resource. Also called stored solar energy, wood burning, agricultural wastes and/or methane gases spin turbines that then generate electricity.
Blocking Diode A diode used to prevent undesired current flow. In a PV array the diode is used to prevent current flow towards a failed module or from the battery to the PV array during periods of darkness or low current production.
Bond Programs Bonds allow governments (and corporations) to raise money by borrowing. A few states and local governments have established bond programs to support energy efficiency and renewable energy for government-owned facilities. After a government has raised an authorized sum of money through the sale of bonds, the money collected is used to improve energy efficiency or to install renewable energy systems at government facilities. The bonding authority is usually reimbursed using the energy savings resulting from these projects.
Booster Pump A surface pump used to increase pressure in a water line, or to pull from a storage tank and pressurize a water system. See Surface Pump.
Braking System A device to slow a wind turbine's shaft speed down to safe levels electrically or mechanically.
British Thermal Unit (BTU) A traditional unit of energy equal to about 1.06 kilojoules. The term "BTU" is used to describe the heat value (energy content) of fuels, and also to describe the power of heating and cooling systems, such as furnaces, stoves, barbecue grills, and air conditioners.
BTU British Thermal Unit-the amount of heat energy needed to raise the temperature of one pound of water by one degree Fahrenheit.
Building Energy Codes Building energy codes adopted by states (and some local governments) require commercial and/or residential construction to adhere to certain energy standards. While some government entities have developed their own building energy codes, many use existing codes, such as the International Energy Conservation Code (IECC), developed and published by the International Code Council (ICC); or ASHRAE 90.1, developed by the American Society of Heating, Refrigerating and Air-Conditioning Engineers (ASHRAE). A few local building energy codes require certain commercial facilities to meet green building standards.
Bypass Diode A diode connected in parallel with a PV module to provide an alternate current path in case of module shading or failure.
C - for Unit of Charge Used to signify a charge or discharge rate equal to the capacity of a battery divided by 1 hour. Thus C for a 1600 mAh battery would be 1.6 A, C/5 for the same battery would be 320 mA and C/10 would be 160 mA. Because C is dependent on the capacity of a battery the C rate for batteries of different capacities must also be different.
Calorie Calories and small calorie. The "small calorie" used in fuel research, is the amount of energy needed to raise the temperature of one gram of water one degree Celsius.
Capacity The capacity of a battery is a measure of the amount of energy that it can deliver in a single discharge. Battery capacity is normally listed as amp-hours (or milli amp-hours) or as watt-hours.
Captive Electrolyte Battery A battery having an immobilized electrolyte (gelled or absorbed in a material).
Carbon Dioxide (CO2) The colorless, odorless gas that is formed during normal human breathing. It is also emitted by combustion activities used to produce electricity. CO2 is a major cause of the greenhouse effect that traps radiant energy near the earth's surface.
Casing Plastic or steel tube that is permanently inserted in the well after drilling. Its size is specified according to its inside diameter.
Cathode Is an electrode that, in effect, oxidizes the anode or absorbs the electrons. During discharge, the positive electrode of a voltaic cell is the cathode. When charging, that reverses and the negative electrode of the cell is the cathode.
CEC California Energy Commission, Mission of the Efficiency and Renewables Division of CEC: The Division is committed to making California's businesses, homes, and appliances more energy efficient. This commitment is achieved by: Developing and implementing energy efficiency building standards that help ensure comfort and affordability Identifying and developing ways to streamline energy use in agriculture, manufacturing, water systems, and processing functions Letting Californians know that using energy wisely is a good investment in the economy and the environment Assist Schools (K-12), Public Colleges & Hospitals, Local Government, and others to identify and implement energy efficiency measures.
Cell An electrochemical device, composed of positive and negative plates and electrolyte, which is capable of storing electrical energy. It is the basic “building block” of a battery.
Centrifugal Pump A pumping mechanism that spins water by means of an "impeller." Water is pushed out by centrifugal force. See also Multi-Stage.
Charge The conversion of electric energy, provided in the form of a current, into chemical energy within the cell or battery.
Charge Controller A device that controls the charging rate and/or state of charge for batteries.
Charge Controller Terminology - Reverse Current Protection Any method of preventing unwanted current flow from the battery to the PV array (usually at night). See Blocking Diode.
Charge Controller Terminology - Activation Voltage(s) The voltage(s) at which the controller will take action to protect the batteries.
Charge Controller Terminology - Adjustable Set Point A feature allowing the user to adjust the voltage levels at which the controller will become active.
Charge Controller Terminology - Charge Factor A number representing the time in hours during which a battery can be charged at a constant current without damage to the battery. Usually expressed in relation to the total battery capacity, i.e., C/5 indicates a charge factor of 5 hours. Related to Charge Rate.
Charge Controller Terminology - Charge Rate The current used to recharge a battery. Normally expressed as a percentage of total battery capacity. For instance, C/5 indicates a charging current equal to one-fifth of the battery's capacity.
Charge Controller Terminology - Conversion Efficiency The ratio of the electrical energy produced by a photovoltaic cell to the solar energy impinging on the cell.
Charge Controller Terminology - High Voltage Disconnect The voltage at which the charge controller will disconnect the array from the batteries to prevent overcharging.
Charge Controller Terminology - High Voltage Disconnect Hysteresis The voltage difference between the high voltage disconnect setpoint and the voltage at which the full PV array current will be reapplied.
Charge Controller Terminology - Low Voltage Disconnect The voltage at which the charge controller will disconnect the load from the batteries to prevent over-discharging.
Charge Controller Terminology - Low Voltage Disconnect Hysteresis The voltage difference between the low voltage disconnect setpoint and the voltage at which the load will be reconnected.
Charge Controller Terminology - Low Voltage Warning A warning buzzer or light that indicates the low battery voltage setpoint has been reached.
Charge Controller Terminology - Maximum Power Tracking or Peak Power Tracking Operating the array at the peak power point of the array's I-V curve where maximum power is obtained.
Charge Controller Terminology - Multi-stage Controller Unit that allows different charging currents as the battery nears full SOC.
Charge Controller Terminology - Reverse Current Protection Any method of preventing unwanted current flow from the battery to the PV array (usually at night). See Blocking Diode.
Charge Controller Terminology - Series Controller A controller that interrupts the charging current by open-circuiting the PV array. The control element is in series with the PV array and battery.
Charge Controller Terminology - Shunt Controller A controller that redirects or shunts the charging current away from the battery. The controller requires a large heat sink to dissipate the current from the short-circuited PV array. Most shunt controllers are for smaller systems producing 30 amperes or less.
Charge Controller Terminology - Single-Stage Controller A unit that redirects all charging current as the battery nears full SOC.
Charge Controller Terminology - Tare Loss Loss caused by the controller. One minus tare loss, expressed as a percentage, is equal to the controller efficiency.
Charge Controller Terminology - Temperature Compensation A circuit that adjusts the charge controller activation points depending on battery temperature. This feature is recommended if the battery temperature is expected to vary more than ±5
Charge Rate The amount of current applied to battery during the charging process. This rate is commonly expressed as a fraction of the capacity of the battery. For example, the C/2 or C/5.
Charging The process of supplying electrical energy for conversion to stored chemical energy.
Charging Voltage The voltage used to overcome a battery's internal resistance and to recharge the battery.
Chord The width of a wind turbine blade at a given location along the length.
circuit directory Is a listing of services provided by each branch circuit breaker in a panel distribution a.k.a. load center a.k.a. panelboard
Clean Energy Synonymous with renewable energy resources.
Closed-Circuit Voltage (CCV) The voltage of a battery when the cell or battery is under a specific discharge load and time interval. See also Open-Circuit Voltage.
Cloud Enhancement The increase in solar intensity caused by reflected irradiance from nearby clouds.
Coercivity The amount of power needed to magnetize or demagnetize a permanent magnet. Measured in MegaGauss Oersted (mGO)
Cogging The cyclic physical resistance felt in some alternator designs from magnets passing the coils and gaps in the laminates. Detrimental to Start-up.
Commutator The rotating part of a DC generator.
Competitive Power Supply Any company that (usually generates then) sells power.
Concentrator Usually a reflective mirror that focuses and enhances the sun's rays onto a photovoltaic surface. This may sometimes refer to a lens with the same purpose.
Connection Charge Fee demanded by utilities for the cost of hooking up new service.
Conservation Achieving the reduction of energy usage through increased efficiency or reduced waste.
Constant-Current Charge A charging process in which the current applied to the battery is maintained at a constant value.
Constant-Voltage Charge A charging process in which the voltage applied to a battery is held at a constant value.
Contractor Licensing Some states have adopted a licensing process for renewable energy contractors. Several states have adopted contractor licensing requirements for solar water heating, active and passive solar space heating, solar industrial process heat, solar-thermal electricity, and photovoltaics (PV). These requirements are designed to ensure that contractors have the necessary knowledge and experience to install systems properly. Solar licenses typically take the form of either a separate, specialized solar contractor’s license, or of a specialty classification under a general electrical or plumbing license.
Converter A unit that converts a dc voltage to another dc voltage.
CSA - Canadian Standards Association The Canadian Standards Association is a not-for-profit membership-based association serving business, industry, government and consumers in Canada and the global marketplace. As a solutions-oriented organization, we work in Canada and around the world to develop standards that address real needs, such as enhancing public safety and health. Advancing the quality of life. Helping to preserve the environment. Facilitating trade.
Customer Service Customer Service for Internet Orders: 800-339-9171 (toll-free).
Cut-In The rotational speed at which an alternator or generator starts pushing electricity hard enough (has a high enough voltage) to make electricity flow in a circuit.
Cutoff Voltage, final The prescribed lower-limit voltage at which battery discharge is considered complete. The cutoff or final voltage is usually chosen so that the maximum useful capacity of the battery is realized. The cutoff voltage varies with the type of battery and the kind of service in which the battery is used. When testing the capacity of a NiMH or NiCD battery a cutoff voltage of 1.0 V is normally used. 0.9V is normally used as the cutoff voltage of an alkaline cell. A device that is designed with too high a cutoff voltage may stop operating while the battery still has significant capacity remaining.
Cycle One sequence of charge and discharge.
Cycle Life For rechargeable batteries, the total number of charge/discharge cycles the cell can sustain before it’s capacity is significantly reduced. End of life is usually considered to be reached when the cell or battery delivers only 80% of rated ampere- hour capacity. NiMH batteries typically have a cycle life of 500 cycles, NiCd batteries can have a cycle life of over 1,000 cycles. The cycle of a battery is greatly influenced by the type depth of the cycle (deep or shallow) and the method of recharging. Improper charge cycle cutoff can greatly reduce the cycle life of a battery.
Deep Cycle A cycle in which the discharge is continued until the battery reaches it’s cut-off voltage, usually 80% of discharge.
Deep cycle battery A battery designed to tolerate up to 80% discharge of its capacity.
Deep Discharge The discharge of the battery to below the specified cutoff voltage before the battery is replaced or recharged.
Deep-Cycle Battery A battery that is designed to withstand repetitive discharges to a 20% depth of discharge or more and to continue providing its rated capacity after hundreds of cycles. Deep-cycle batteries are often used in marine/RV and industrial applications
Depth of Discharge The amount of energy that has been removed from a battery (or battery pack). Usually expressed as a percentage of the total capacity of the battery. For example, 50% depth of discharge means that half of the energy in the battery has been used. 80% DOD means that eighty percent of the energy has been discharged, so the battery now holds only 20% of its full charge.
Depth of discharge (DOD) The amount of energy (expressed in percentage of its rated capacity) withdrawn from a battery, a battery bank or a cell.
Deregulation Governmental relaxation of controls. In terms of the electricity market, deregulation refers to ending monopolies by local utilities and allowing privatization.
Direct Current (DC) Electric current flowing in one direction in invariable amperage. This is most often associated with battery power.
Discharge The conversion of the chemical energy of the battery into electric energy.
Discharge Rate The rate at which current is drawn from a battery, usually expressed in amps.The state of a battery when it has less than a 100% state of charge. Levels of discharge are shown in the Open-Circuit-Voltage Chart.
Discharge, deep Withdrawal of all electrical energy to the end-point voltage before the cell or battery is recharged.
Discharge, high-rate Withdrawal of large currents for short intervals of time, usually at a rate that would completely discharge a cell or battery in less than one hour.
Discharge, low-rate Withdrawal of small currents for long periods of time, usually longer than one hour.
Discharged The state of a battery when it has less than a 100% state of charge. Levels of discharge are shown in the Open-Circuit-Voltage Chart.
Distilled water If the water level in your battery is low, Interstate Batteries recommends adding nothing but distilled water to a vehicle battery. No other additives have been proven to extend battery life and may actually decrease it.
Distributed Energy Generation Electricity that is provided by small power generators located at or near end users.
DOD Depth of Discharge (DOD) The percent of rated capacity to which a cell or battery is discharged. It is the reciprocal of a battery's state of charge. Example: a battery that has a depth of discharge of 45% has a state of charge of 55%.
Drag In a wind generator, the force exerted on an object by moving air. Also refers to a type of wind generator or anemometer design that uses cups instead of a blades with airfoils.
Drain Withdrawal of current from a cell.
Drawdown Lowering of level of water in a well due to pumping.
Dry Cell A primary cell in which the electrolyte is absorbed in a porous medium, or is otherwise restrained from flowing. Common practice limits the term “dry cell” to the Leclanch‚ cell, which is the common commercial type.
Dump Load A device to which wind generator power flows when the system batteries are too full to accept more power, usually an electric heating element. This diversion is performed by a Shunt Regulator, and allows a Load to be kept on the Alternator or Generator.
Duty Cycle The ratio of active time to total time. Used to describe the operating regime of appliances or loads in PV systems.
Duty Rating The amount of time an inverter (power conditioning unit) can produce at full rated power.
Efficiency The ratio of output power (or energy) to input power (or energy). Expressed in percent.
Electric utility Any agency or authority aligned with distribution facilities for delivery of electrical energy to the public. The notion of utility varies widely from state to state and from time to time, depending on fickle laws concerning regulation and deregulation.
Electric Utility Restructuring Also called deregulation, this is the introduction of competition into various phases of electricity production.
Electrochemical Couple The system of active materials within a cell that provides electrical energy storage through an electrochemical reaction.
Electrode An electrical conductor through which an electric current enters or leaves a conducting medium, whether it be an electrolytic solution, solid, molten mass, gas, or vacuum. For electrolytic solutions, many solids, and molten masses, an electrode is an electrical conductor at the surface of which a change occurs from conduction by electrons to conduction by ions. For gases and vacuum, the electrodes merely serve to conduct electricity to and from the medium.
Electrolyte A chemical compound which, when fused or dissolved in certain solvents, usually water, will conduct an electric current. All electrolytes in the fused state or in solution give rise to ions which conduct the electric current.
Electromagnet A device made of wire coils that produces a magnetic field when electricity flows through the coils.
Electropositivity The degree to which an element in a galvanic cell will function as the positive element of the cell. An element with a large electropositivity will oxidize faster than an element with a smaller electropositivity.
Emissions In the context of global warming, this is the release of radiatively relevant greenhouse gases (one example is the release of carbon dioxide during fuel combustion in an automobile engine.)
End-of-Discharge Voltage The voltage of the battery at termination of a discharge.
Energy The capacity to do work.
Energy - Output Capability Expressed as capacity times voltage, or watt-hours.
Energy Density Ratio of cell energy to weight or volume (watt-hours per pound, or watt-hours per cubic inch).
Energy Efficient A qualification of electrical products, in which they achieve an appropriate ratio of energy usage to work-type output. For example, an energy efficient light bulb will use most of the input electrical energy to produce light, not heat.
Energy Sources Three primary categories are fossil fuels (coal, oil, gas); nuclear (fission and fusion); and renewable (solar, wind, geothermal, biomass, hydro).
Energy Standards for Public Buildings Many states and local governments, as well as the federal government, have chosen to lead by example by requiring new government buildings to meet strict energy standards. DSIRE includes policies that have established green building standards, energy-reduction goals, equipment-procurement requirements, and/or the use of on-site renewable energy. Many of these policies require that new government buildings (and renovated buildings, in some cases) attain a certain level of certification under the U.S. Green Building Council’s Leadership in Energy and Environmental Design (LEED) program. Equipment-procurement policies often mandate the use of the most efficient equipment, including equipment that meets federal Energy Star criteria. Policies designed to encourage the use of on-site renewables generally establish conditional requirements tied to life-cycle cost analysis.
Equalization Charge The process of mixing the electrolyte in batteries by periodically overcharging the batteries for a short time.
EqualizingCharge A charging method that equalizes the specific gravity or voltage levels of individual cells in a battery or a group of batteries connected in series.
Equipment Certification Requirements Policies requiring renewable energy equipment to meet certain standards serve to protect consumers from buying inferior equipment. These requirements not only benefit consumers; they also protect the renewable energy industry by keeping substandard systems out of the market.
Escape Provision A contract provision allowing a party, such as an electric customer, to get out of it, usually after paying a pre-set penalty.
Evacuated Tube Used in solar thermal collectors, these are glass absorber tubes with the air evacuated and through which collector fluids (water or perhaps glycol) flows.
fast charge Fast-Charge a high rate charge — typically above 20 amps — for one to five hours that provides a quick blast of energy. It is often used to get the battery to a recharge level that can restart a vehicle. Repeated fast charges overcharge the battery and reduce service life.
FERC In the USA, The Federal Energy Regulatory Commission is an independent government agency that regulates rates charged by public utilities. Its jurisdiction is somewhat disputed but it includes the sale of electric power for resale.
Fill Factor For an I-V curve, the ratio of the maximum power to the product of the open-circuit voltage and the short-circuit current. Fill factor is a measure of the "squareness" of the I-V curve.
Fixed Tilt Array A PV array set in at a fixed angle with respect to horizontal.
Flat Plate Pumped Most widely used among solar thermal collectors, this typically consists of a metal frame, glazing, absorbers (usually metal), and insulation with a pump liquid (typically glycol) as the heat-transfer medium: used in water heating applications.
Flat-Plate Array A PV array that consists of non-concentrating PV modules.
Float Charge Charge current to a battery that is equal to or slightly greater than the self discharge rate.
Float Charging Method of recharging in which a secondary cell is continuously connected to a constant-voltage supply that maintains the cell in fully charged condition. Typically applied to lead acid batteries.
Fluorescent light A lighting device which uses an electrified gas rather than filament.
Fossil fuels Fuels (oil, coal and gas) formed eons ago from decayed plants and animals.
Friction Loss The loss of pressure due to flow of water in pipe. This is determined by 3 factors: pipe size (inside diameter), flow rate, and length of pipe. It is determined by consulting a friction loss chart available in an engineering reference book or from a pipe supplier. It is expressed in PSI or Feet (equivalent additional feet of pumping).
FSEC - Florida Solar Energy Centre FSEC is one of the nation's leading certification and testing laboratories for solar products and equipment. The center’s expertise is based on nearly 30 years experience conducting solar energy certification and testing programs, the accreditation of PowerMark Corporation (PMC) and partnerships with such national associations as the American Society of Heating, Refrigerating and Air Conditioning Engineers (ASHRAE), The National Association of State Energy Offices (NASEO), and the Solar Rating & Certification Corporation (SRCC).
Fuel Cell A device producing electricity at high efficiency using a fuel and a chemical (usually an oxidizer) that reacts with it at two separate terminals, producing electricity.
Furling Tail A wind generator protection mechanism where the rotor shaft axis is offset horizontally from the yaw axis, and the tail boom is both offset horizontally and hinged diagonally, thus allowing the tail to fold up and in during high winds. This causes the blades to turn out of the wind, protecting the machine.
Galvanic Cell A combination of electrodes, separated by electrolyte, that is capable of producing electrical energy by electrochemical action.
Gassing The evolution of gas from one or both of the electrodes in a cell. Gassing commonly results from self-discharge or from the electrolysis of water in the electrolyte during charging.
Generation The act of producing electricity.
Geothermal Heat from the earth. Customarily applied to energy from geysers and hot springs (which is now better characterized as hydro-geothermal), in recent years, this term is applied to any heat stored in earth and available as a renewable energy resource.
GFCI Ground Fault Circuit Interrupter. GFCI is a device that protects against electric shock. A GFCI trips and stops the flow of power when leakage current is detected.
GFDI Ground-Fault Detector Interrupter(GFDI) is a residual-current device (RCD), or residual-current circuit breaker (RCCB), is an electrical wiring device that disconnects a circuit whenever it detects that the electric current is not balanced between the energized conductor and the return neutral conductor or the grounding conductor. It is an "Appliance Leakage Current Interrupter" (ALCI). Ground Fault Condition is defined as: An unintentional, electrically conducting connection between an ungrounded conductor of an electrical circuit and the normally non-current-carrying conductors, metallic enclosures, metallic raceways, metallic equipment or earth.
Global warming The earth's gradual warming due to the "greenhouse effect."
Gravity Flow The use of gravity to produce pressure and water flow. A storage tank is elevated above the point of use, so that water will flow with no further pumping required. A booster pump may be used to increase pressure. 2.31 Vertical Feet = 1 PSI. See pressure.
Green Building Incentives Green buildings are designed and constructed using practices and materials that minimize the impacts of the building on the environment and human health. Many cities and counties offer financial incentives to promote green building. The most common form of incentive is a reduction or waiver of a building permit fee. The U.S. Green Building Council’s Leadership in Energy and Environmental Design (LEED) is a popular point-based certification program for green buildings. The LEED system awards points for site selection and development; material, energy and water efficiency; indoor air quality; innovation; and the application of renewable technologies. (Note that this category includes green building incentives that do not fall under other DSIRE incentive categories, such as tax incentives and grant programs.)
Green Power Purchasing Policies Government entities, businesses, residents, schools, non-profits and others can play a significant role in supporting renewable energy by buying electricity from renewable resources, or by buying renewable energy credits (RECs). Many state and local governments, as well as the federal government, have committed to buying green power to account for a certain percentage of their electricity consumption. Green power purchases are typically executed through contracts with green power marketers or project developers, through utility green power programs, or through community aggregation.
Greenhouse effect The effect achieved by the buildup of gases (e.g. CFC's and carbon dioxide) in the earth's atmosphere causing the earth to become hot (as a greenhouse).
Grid The electrical distribution system, as laid out by wires, conductors, stations, etc.
Grid Tie An electrical system that is connected to a utility distribution grid. For example, Xantrex SW line tie inverters are designed to connect to and interact with utility power.
Grid-Interactive System. See Utility interactive system. Also called a Grid-inter-tied system.
Ground The reference potential of a circuit. In automotive use, the result of attaching one battery cable to the body or frame which is used as a path for completing a circuit in lieu of a direct wire from a component. This method is not suitable for connecting the negative cable of the inverter to ground. Instead, route the cable directly to the negative terminal of the battery.
Guy Anchor Attaches tower guy wires securely to the earth.
Guy Radius The distance between a wind turbine tower and the guy anchors.
Guy Wire Attaches a tower to a Guy Anchor and the ground.
HEAD The vertical distance that water is pumped. This determines the pressure that the pump pushes against. Total vertical lift = vertical lift from the surface of water source up to the discharge in the tank + (in a pressure system) discharge pressure. Synonym: static head. Note: Horizontal distance does NOT add to the vertical lift, except in terms of pipe friction loss. NOR does the volume (weight) of water contained in pipe or tank. Submergence of the pump does NOT add to the vertical lift in the case of a centrifugal type pump. In the case of a positive displacement pump, it may add to the lift somewhat. See Vertical Lift and Total Dynamic Head. In water distribution, synonym: vertical drop.
heatload Heat load (including heat loss, or heat gain) is the term for the amount of heating (heat loss) or cooling (heat gain) needed to maintain desired temperature and humidity in controlled transfer fluid.
Heavy-Duty Battery (Commercial) A lead-acid, liquid-electrolyte, starting battery used in medium and heavy-duty trucks, construction vehicles and other off-road vehicles.
Horizontal Axis Wind Turbine A "normal" wind turbine design, in which the shaft is parallel to the ground, and the blades are perpendicular to the ground.
Hydrometer An instrument — normally a mechanical float type device but can be electronic — used to determine the state of charge of a battery by measuring the specific gravity of its electrolyte.
Hydropower Power obtained from the (typically gravitational) movement of water.
I-V Curve The plot of the current versus voltage characteristics of a photovoltaic cell, module, or array. Three important points on the I-V curve are the open-circuit voltage, short-circuit current, and peak power operating point.
Incandescent light A bulb using resistance to produce light when an electrical current passes through it. The conductor is usually a wire or filament.
Incentives Subsidies, tax breaks and other Government actions, in which indirect money is given to consumers under certain conditions.
Insolation Solar radiant energy impinging on the earth in any given region or area.
Interconnection Standards Interconnection standards set forth the technical and procedural process by which a customer connects an electricity-generating system to the grid. Interconnection standards include the technical and contractual arrangements that system owners and utilities must abide by. Standards for systems connected at the distribution level are typically adopted by state public utility commissions, while the Federal Energy Regulatory Commission (FERC) has adopted standards for systems connected at the transmission level. Most states have adopted interconnection standards, but some states’ standards apply only to investor-owned utilities -- not to municipal utilities or electric cooperatives.
Internal Resistance The resistance to the flow of an electric current within the cell or battery.
Inverter A device that changes direct current (DC) into alternating current (AC).
Inverter Terminology - Duty Rating This rating is the amount of time the inverter can supply its rated power. Some inverters can operate at their rated power for only a short time without overheating.
Inverter Terminology - Frequency Most loads in the United States require 60 Hz. High-quality equipment requires precise frequency regulation--variations can cause poor performance of clocks and electronic timers.
Inverter Terminology - Frequency Regulation This indicates the variability in the output frequency. Some loads will switch off or not operate properly if frequency variations exceed 1 percent.
Inverter Terminology - Input Voltage This is determined by the total power required by the ac loads and the voltage of any dc loads. Generally, the larger the load, the higher the inverter input voltage. This keeps the current at levels where switches and other components are readily available.
Inverter Terminology - Modified Sine Wave A waveform that has at least three states (i.e., positive, off, and negative). Has less harmonic content than a square wave.
Inverter Terminology - Modularity The use of multiple inverters connected in parallel to service different loads.
Inverter Terminology - Power Conversion Efficiency The ratio of output power to input power of the inverter.
Inverter Terminology - Power Factor The cosine of the angle between the current and voltage waveforms produced by the inverter. For resistive loads, the power factor will be 1.0.
Inverter Terminology - Rated Power Rated power of the inverter. However, some units can not produce rated power continuously. See duty rating.
Inverter Terminology - Root Mean Square (RMS) The square root of the average square of the instantaneous values of an ac output. For a sine wave the RMS value is 0.707 times the peak value. The equivalent value of ac current, I, that will produce the same heating in a conductor with resistance, R, as a dc current of value I.
Inverter Terminology - Sine Wave A waveform corresponding to a single-frequency periodic oscillation that can be mathematically represented as a function of amplitude versus angle in which the value of the curve at any point is equal to the sine of that angle.
Inverter Terminology - Square Wave A wave form that has only two states, (i.e., positive or negative). A square wave contains a large number of harmonics.
Inverter Terminology - Standby Current This is the amount of current (power) used by the inverter when no load is active (lost power). The efficiency of the inverter is lowest when the load demand is low.
Inverter Terminology - Surge Capacity The maximum power, usually 3-5 times the rated power, that can be provided over a short time.
Inverter Terminology - Voltage Protection Many inverters have sensing circuits that will disconnect the unit from the battery if input voltage limits are exceeded.
Inverter Terminology - Voltage Regulation This indicates the variability in the output voltage. Some loads will not tolerate voltage variations greater than a few percent.
Irradiance The solar power incident on a surface. Usually expressed in kilowatts per square meter. Irradiance multiplied by time equals Insolation.
Jack Pump is actually a mixture of the 2 types. The motor, gears, & electrical are on the surface, but move a shaft (sucker rod) that attaches to the pump which is submerged. Good for very deep wells.Example: Solamotor Jack Pump
Jet Pump A surface-mounted centrifugal pump that uses an "ejector" (venturi) device to augment its suction capacity. In a "deep well jet pump" the ejector is down in the well to assist the pump in overcoming the limitations of suction. (Some water is diverted back down the well, causing an increase in energy use.)
Joules A measure of work or energy used in the Imperial System. measure of work or energy. A simple definition is that a joule is the work required to lift a mass of about 100 g for one meter under the earth's gravity.
Kilowatt Equal to one thousand watts. This unit is typically used to express the output power of engines and the power consumption of tools and machines. It is also a common unit used to express the electromagnetic power output of radio transmitters.
Kilowatt (kW) One thousand watts of electricity (See Watt).
Kilowatthour (kWh) One thousand watthours.
Lead-acid battery Slightly larger than a car battery, these have internal plates made of lead or a lead alloy, surrounded by a sulfuric acid electrolyte. Car batteries are made with softer plates. Lead-acid batteries are commonly used in solar and wind energy systems.
Leeward Away from the direction from which the wind blows.
Lift The force exerted by moving air on asymmetrically-shaped wind generator blades at right angles to the direction of relative movement. Ideally, wind generator blades should produce high Lift and low Drag.
line terminals the electrical wiring and associated devices such as switches, meters and light fittings used in buildings or other structures, being energized.
Line wire loss Voltage or power lost due to the resistance of wires in an electric circuit. Power loss is often proportional to wire length and is far greater in DC than AC.
Linear Current Booster (LCB) An electronic device which varies the voltage and current of a PV array to match the needs of an array-direct pump, especially a positive displacement pump. It allows the pump to start and to run under low sun conditions without stalling. Electrical analogy: variable transformer. Mechanical analogy: automatic transmission. Also called pump controller. See Pump Controller.
Liquid Electrolyte Battery A battery containing a liquid solution of acid and water. Distilled water may be added to these batteries to replenish the electrolyte as necessary. Also called a flooded battery because the plates are covered with the electrolyte.
Livestock or irrigation water is pumped to an open stock tank for animals or to gardens, etc.
Load The electricity required and used by any single or collection of electrical item(s).
Load Center Is a component of an electricity supply system which divides an electrical power feed into subsidiary circuits, while providing a protective fuse or circuit breaker for each circuit in a common enclosure.
Load Centers Is a component of an electricity supply system which divides an electrical power feed into subsidiary circuits, while providing a protective fuse or circuit breaker for each circuit in a common enclosure.
Load Profile Collected information on a customer's usage over a set period of time. It is sometimes shown as a graph on the customer's bill.
Losses Power that is harvested by a wind generator but is not transferred to a usable form. Losses can be from friction, electrical resistance, or other causes.
Mandatory Utility Green Power Option Several states require electric utilities to offer customers the option to buy electricity generated from renewable resources, commonly known as “green power.” Typically, utilities offer green power generated using renewable resources that the utilities own (or for which they contract), or they buy renewable energy credits (RECs) from a provider certified by a state public utilities commission.
Maximum power point (MPP) The voltage at which a PV array is producing maximum power.
Maximum power point tracker (MPPT) A power conditioning unit that increases the power of a PV system by ensuring operation of the PV generator at its Maximum Power Point (MPP). The ability to do so can depend on climate and the battery's state of charge.
Maximum Power Point Tracking a technology used in newer charge controllers which allows more power to reach the batteries. This is achieved with a very high efficiency dc to dc converter - which converts the normal 17.4v coming from the solar panel into 13.7v to charge the battery. As a result the charging current is higher - sometimes by up to a 33% gain.
Megawatt (MW) One million watts of electricity (See Watt).
Megawatt-hour One thousand kilowatt-hours or 1 million watt-hours.
Memory Effect for Battery Cells A phenomenon in which a cell, operated in successive cycles to less than full, depth of discharge, temporarily loses the remainder of its capacity at normal voltage levels (usually applies only to Ni-Cd cells). Note, memory effect can be induced in NiCd cells even if the level of discharge is not the same during each cycle. Memory effect is reversible.
MMBTU (Mega Mega British Thermal Unit) Represents one million British Thermal Units.
MPPT A technology used in newer charge controllers which allow more power to reach the batteries. This is achieved with a very high-efficiency DC to DC converter - which converts the normal 17.4v coming from the solar panel into 13.7v to charge the battery. As a result, the charging current is higher - sometimes by up to a 33% gain.
MPPT - How does the MPPT work The MPPT charge controller operates at extremely high audio frequencies which are of the 20 to 80 KHz range. The MPPT charge controller compares the output of the solar panels with that of the battery voltage. Then it determines the power the panels need to produce to charge the batteries. Most of the MPPT charge controllers have an efficiency level of 92 to 97 percent in the conversion process. You gain power in winter by almost 20 to 45 percent and 10 to 15 percent in summer. The actual gain depends on a lot of factors like the temperature, weather and the battery's state of charge. 
MPPT Charge Controller MPPT charge controller is a maximum power point tracker which is an electronic DC to DC converter which takes the DC input from the solar panels, changes it to high frequency AC and converts it back to a different DC current to match with the batteries. This is a solely electronic tracking system and not concerned with the panel system at all. 
Negative Terminal The terminal of a battery from which electrons flow in the external circuit when the cell discharges. See Positive Terminal.
Net Metering For electric customers who generate their own electricity, net metering allows for the flow of electricity both to and from the customer – typically through a single, bi-directional meter. When a customer’s generation exceeds the customer’s use, electricity from the customer flows back to the grid, offsetting electricity consumed by the customer at a different time during the same billing cycle. In effect, the customer uses excess generation to offset electricity that the customer otherwise would have to purchase at the utility’s full retail rate. Net metering is required by law in most U.S. states, but these policies vary widely.
Nickel Cadmium Battery A battery containing nickel and cadmium plates and an alkaline electrolyte.
Nonaqueous Batteries Cells that do not contain water, such as those with molten salts or organic electrolytes.
North American Board of Certified Energy Practitioners (NABCEP) The North American Board of Certified Energy Practitioners (NABCEP) is a volunteer board of renewable energy stakeholder representatives that includes representatives of the solar industry, NABCEP certificants, renewable energy organizations, state policy makers, educational institutions, and the trades. Each member of the board was chosen because of his or her experience and involvement in the solar energy industry. NABCEP’s mission–to support, and work with, the renewable energy and energy efficiency industries, professionals, and stakeholders–is intended to develop and implement quality credentialing and certification programs for practitioners.
NREL - National Renewable Energy Laboratory The National Renewable Energy Laboratory (NREL) has research facilities and offices at several locations in Golden, near Boulder, and in Washington, D.C. In Golden, Colorado, you'll find the NREL Visitors Center, along with many of our research laboratories and administrative offices. The National Wind Technology Center is a separate facility located between Golden and Boulder.
Off Grid An electrical system that is not connected to a utility distribution grid.
Off Peak The period of low energy demand, as opposed to maximum, or peak, demand.
Off Peak/ On Peak Times when energy demand and price is low (off-peak) or high (on-peak).
Ohm’s Law The formula that describes the amount of current flowing through a circuit. Ohm's Law - In a given electrical circuit, the amount of current in amperes (I) is equal to the pressure in volts (V) divided by the resistance, in ohms (R). Ohm's law can be shown by three different formulas: To find Current I = V/R To find Voltage V = I x R To find Resistance R = V/I
Open Circuit Condition of a battery which is neither on charge nor on discharge (i.e., disconnected from a circuit).
Open Discharge The filling of a water vessel that is not sealed to hold pressure. Examples: storage (holding) tank, pond, flood irrigation. Contrast: Pressure Tank.
Open-Circuit Voltage The difference in potential between the terminals of a cell when the circuit is open (i.e., a no-load condition).
Oxidation A chemical reaction that results in the release of electrons by an electrode’s active material.
PACE Financing Property-Assessed Clean Energy (PACE) financing effectively allows property owners to borrow money to pay for renewable energy and/or energy-efficiency improvements. The amount borrowed is typically repaid over a period of years via a special assessment on the owner's property. In general, local governments (such as cities and counties) that choose to offer PACE financing must be authorized to do so by state law.
Panelboard Is a component of an electricity supply system which divides an electrical power feed into subsidiary circuits, while providing a protective fuse or circuit breaker for each circuit in a common enclosure.
Parallel Connection The arrangement of cells in a battery made by connecting all positive terminals together and all negative terminals together. The voltage of the group remains the same as the voltage of the individual cell. The capacity is increased in proportion to the number of cells.
Passive Solar A system in which solar energy alone is used for the transfer of thermal energy. Pumps, blowers, or other heat transfer devices that use energy other than solar are not used.
Peak Maximum energy demand or load in a specified time period.
Peak Demand Maximum energy demand or load in a specified time period.
Peak load The maximum demand for energy on a utility system which has to be met by the utility's power generating capacity.
Peak Power Power generated that operates at a very low capacity factor; typically used to meet short-lived, variable high demand periods.
Peak Shifting The process of moving existing loads to off-peak periods.
Peak Watt A manufacturer's unit indicating the amount of power a photovoltaic cell or module will produce at standard test conditions (normally 1,000 watts per square meter and 25 degrees Celsius).
Peaking Capacity Power generation equipment or system capacity to meet peak power demands.
Performance-Based Incentives Performance-based incentives (PBIs), also known as production incentives, provide cash payments based on the number of kilowatt-hours (kWh) or BTUs generated by a renewable energy system. A "feed-in tariff" is an example of a PBI. To ensure project quality, payments based on a system’s actual performance are generally more effective than payments based on a system’s rated capacity. (Note that tax incentives based on the amount of energy produced by an eligible commercial facility are categorized as “Corporate Tax Incentives” in DSIRE.)
Photovoltaic (PV) The production of electricity from light. See also Solar cell.
Pitch The angle between the blade Chord and the plane of the blade's rotation. Also called Pitch or blade angle. A blade carved with a Twist has a different setting angle at the Tip than at the Root.
Polarity Refers to the charges residing at the terminals of a battery.
Positive (+) Normally refers to the positive (+) battery terminal, which is the point to which electrons in the external circuit flow during discharge. Sometimes the positive (+) terminal cap or cable is red, designating positive (+)
Positive Termina The terminal of a battery toward which electrons flow through the external circuit when the cell discharges. See Negative Terminal.
Power The rate of doing work, expressed in watts (W). For example, a generator that is rated at 750 watts will be able to produce that amount of power continuously.
Power Distribution Center power distribution center (PDC) is complex electrical equipment, designed to regulate the distribution of electrical power to equipment in a factory. Typically, switchgear supplies power to the PDC. The PDC housing contains a transformer, which steps down the incoming power to a lower voltage to feed other plant loads such as motor control centers (MCC's). Feeder breakers for these loads will be located on the PDC. PDC's will often contain additional protective relays, monitoring equipment, fuses, terminal points, etc.
Power Distribution Panels Power Distribution Panels are the bare bones of load centers or boardpanels, Using their existing configuration we can add the elements we need to build a load center the way we may consider. In such we can use all the aspects of the existing layout of a Distribution Panel or we can use a portion of that layout.
Power Factor Power factor is the ratio between true power (Watts) and apparent power (Volt Amps)
Pressure The amount of force applied by water that is either forced by a pump, or by the gravity. Measured in pounds per square inch (PSI). PSI = vertical lift (or drop) in Feet / 2.31. 20
Pressure Switch An electrical switch actuated by the pressure in a pressure tank. When the pressure drops to a low set-point (cut-in) it turns a pump on. At a high point (cut-out) it turns the pump off.
Primary Battery A battery made up of primary cells. See Primary Cell.
Primary Cell A cell designed to produce electric current through an electrochemical reaction that is not efficiently reversible. The cell, when discharged, cannot be efficiently recharged by an electric current. Alakline, lithium, and zinc air are common types of primary cells.
Priming The process of hand-filling the suction pipe and intake of a surface pump. Priming is generally necessary when a pump must be located above the water source. A self-priming pump is able to draw some air suction in order to prime itself, at least in theory.
Public Benefit Funds Most public benefit funds (PBFs) were developed by states during the electric utility restructuring era, in the late 1990s, to ensure continued support for renewable energy, energy efficiency and low-income energy programs. These funds are commonly supported through a very small surcharge on electricity consumption (e.g., $0.002/kWh). This charge is sometimes referred to as a "system benefits charge" (SBC). PBFs commonly support rebate programs, loan programs, research and development, and energy education programs.
Public Utility Regulatory Policies Act (PURPA) In the USA only: this is part of the National Energy Act. PURPA is intended to encourage the conservation of energy, more efficient use of resources, and equitable energy rates. Some important measures relevant to The Solar Guide include sections on net metering and incentives for renewable energy.
Pulse-width modulation Is a commonly used technique for controlling power to inertial electrical devices. The average value of voltage (and current) fed to the load is controlled by turning the switch between supply and load on and off at a fast pace. The longer the switch is on compared to the off periods, the higher the power supplied to the load is
PWM Is a commonly used technique for controlling power to inertial electrical devices. The average value of voltage (and current) fed to the load is controlled by turning the switch between supply and load on and off at a fast pace. The longer the switch is on compared to the off periods, the higher the power supplied to the load is.
Quadrillion BTU 10 to the 15th power BTU.
Rated Capacity The number of ampere-hours a cell can deli
Rebate Programs States, utilities and a few local governments offer rebates to promote the installation of renewable energy systems and energy efficiency measures. The majority of rebate programs that support renewables are administered by states, municipal utilities and electric cooperatives; these programs commonly provide funding for solar water heating and/or photovoltaic (PV) systems. Most rebate programs that support energy efficiency are administered by utilities. Rebate amounts vary widely by technology and program administrator.
Rechargeable Capable of being recharged; refers to secondary cells or batteries.
Recombination State in which the gases normally formed within the battery cell during its operation, are recombined to form water.
Reduction A chemical process that results in the acceptance of electrons by an electrode’s active material.
Regulator A device to adjust incoming power so as to avoid overcharging a battery bank. In solar power, the regulator generally just turns the solar array off when the batteries are full. With a wind generator, the regulator generally diverts all or part of the incoming power to a Dump Load when the batteries fill, thus keeping a Load on the wind generator so it will not Freewheel.
Renewable energy Energy from sources that cannot be used up or that are naturally replenishing: sunshine, water flow, wind and vegetation. Some add the qualification, "cannot be used up in one lifetime." Still other note that these are "flow-limited," in that there is a limited amount of energy per unit of time.
Renewable Portfolio Standards Renewable portfolio standards (RPSs) require utilities to use renewable energy or renewable energy credits (RECs) to account for a certain percentage of their retail electricity sales -- or a certain amount of generating capacity -- according to a specified schedule. (Renewable portfolio goals are similar to RPS policies, but renewable portfolio goals are not legally binding.) Most U.S. states have established an RPS. The term “set-aside” or “carve-out” refers to a provision within an RPS that requires utilities to use a specific renewable resource (usually solar energy) to account for a certain percentage of their retail electricity sales (or a certain amount of generating capacity) according to a set schedule.
Reserve Capacity (RC) BCI defines it as "the number of minutes a new, fully-charged battery at 80ºF (27ºC) can be discharged at 25 amps and maintain a voltage equal to or higher than 1.75 volts per cell" (i.e., 10.5 volts for a 12-volt battery). This rating represents the time the battery will continue to operate essential accessories in the event of a charging system failure.
Resistance Property of a material that resists the flow of electrons when a potential difference is applied across it. This is measured in Ohms. Resistance is the quality that causes electricity to produce light in a filament or heat in an electrical heater of any kind.
Resistor Any electronic component that restricts the flow of electrical current in circuits. These are often used intentionally to produce heat or light (e.g. a stove element or a light bulb filament).
RETScreen International RETScreen International Clean Energy Project Analysis Tools.
Ribbon Silicon A type of single-crystal silicon that produced in sheets or ribbons.
Root The area of a blade nearest to the hub. Generally the thickest and widest part of the blade.
Rotor 1) The blade and hub assembly of a wind generator. 2) The disc part of a vehicle disc brake. 3) The armature of a permanent magnet alternator, which spins and contains permanent magnets.
Savonius A vertical-axis wind turbine design by S.J. Savonius of Finland from the 1920s and 30s. Shaped like a barrel split from end to end and offset along the cut. They are drag machines, and thus give very low rpm but lots of torque.
Seal The structural part of a galvanic cell that restricts the escape of solvent or electrolyte from the cell and limits the ingress of air into the cell (the air may dry out the electrolyte or interfere with the chemical reactions).
Sealed Battery A battery with a captive electrolyte and a resealing vent cap, also called a valve-regulated battery. Electrolyte cannot be added.
Secondary Battery A battery made up of secondary cells. See Storage Battery; Storage Cell.
Self Discharge Discharge that takes place while the battery is in an open-circuit condition.
Self-Discharge The discharge that occurs in a battery while it is not in use. The higher the temperature, the greater the rate of self-discharge
Self-Discharge Rate The rate at which a cell or battery loses its capacity when standing idle
Separator The permeable membrane that allows the passage of ions, but prevents electrical contact between the anode and the cathode.
Series Connection The arrangement of cells in a battery configured by connecting the positive terminal of each successive cell to the negative terminal of the next adjacent cell so that their voltages are cumulative. See Parallel Connection.
Series Regulator Type of battery charge regulator where the charging current is controlled by a switch connected in series with the PV module or array.
Shallow Cycling Charge and discharge cycles which do not allow the battery to approach it’s cutoff voltage. Shallow cycling of NiCd cells lead to “memory effect”. Shallow cycling is not detrimental to NiMH cells and it is the most beneficial for lead acid batteries.
Shallow-Cycle Battery A battery with small plates that cannot withstand many discharges to a low SOC.
Shelf Life For a dry cell, the period of time (measured from date of manufacture), at a storage temperature of 21 degrees C (69 degrees F), after which the cell retains a specified percentage (usually 90%) of its original energy content.
Short-Circuit Current That current delivered when a cell is short-circuited (i.e., the positive and negative terminals are directly connected with a low-resistance conductor).
Short-Ciruit A condition that occurs when a short electrical path is unintentionally created. Batteries can supply hundreds of amps if short-circuited, potentially melting the terminals and creating sparks.
Shunt A shunt (a current shunt resistor or an ammeter shunt) is a high precision resistor which can be used to measure the current flowing through a circuit.
Shunt regulator Type of a battery charge regulator where the charging current is controlled by a switch connected in parallel with the PV generator. Overcharging of the battery is prevented by shorting the PV generator.
Shunt Resistor A shunt resistor or an ammeter shunt is a high precision resistor which can be used to measure the current flowing through a circuit.
Silicon Semiconductor material made from silica, purified for photovoltaic applications.
Sine Wave Inverter An inverter that produces utility-quality sine wave power forms.
Single Crystal Silicon An very pure (and very expensive) form of crystalline silicon produced by the Czochralski method. This involves dipping a single crystal seed into a reservoir of molten silicon under refined conditions and slowly withdrawing a solidifying single crystal rod of silicon that is then fabricated into single-crystal photovoltaic cells.
slow charge Charging at a rate of about 5-10% of a battery's rated capacity. Example: 50 AH battery x 10% = 5-amp charge
Solar and Wind Access Laws Solar and wind access laws are designed to establish a right to install and operate a solar or wind energy system at a home or other facility. Some solar access laws also ensure a system owner’s access to sunlight. These laws may be implemented at both the state and local levels. In some states, access rights prohibit homeowners associations, neighborhood covenants and local ordinances from restricting a homeowner’s right to use solar energy. Easements, the most common form of solar access law, allow for the rights to existing access to a renewable resource on the part of one property owner to be secured from an owner whose property could be developed in such a way as to restrict that resource. An easement is usually transferred with the property title. At the local level, communities use several policies to protect solar access, including solar access ordinances, development guidelines requiring proper street orientation, zoning ordinances that contain building height restrictions, and solar permits.
Solar and Wind Permitting Standards Permitting standards can facilitate the installation of wind and solar energy systems by specifying the conditions and fees involved in project development. Some local governments have adopted simplified or expedited permitting standards for wind and/or solar. “Top-of-the-stack” permitting (or fast-track permitting) saves system owners and project developers time and money. Some states have capped fees that local governments may charge for a permit for a solar or wind energy system. In addition, some states have developed (or have supported the development of) model wind ordinances for use by local governments.
Solar cell A device made of silicon and semiconductor materials, producing electricity when exposed to sunlight. Movement of electrons is produced by fabrication of adjacent layers of materials with different characteristics.
Solar cooling The use of devices that absorb sunlight to facilitate convection, similar to processes used in gas-fired refrigerators.
Solar electricity Electricity produced in photovoltaic processes, by action of sunlight.
Solar energy The radiant energy of the sun. This can be converted into usable forms of energy, such as heat or electricity.
Solar modules Also called solar panels, these are the large collections of solar cells that can produce electricity at a worthwhile rate. These are packaged for end use and suited to be incorporated into solar energy or solar electricity) systems.
Solar panels See solar modules.
Solar Photovoltaic The process of converting the sun's energy into electricity.
Solar Thermal collector A device designed to collect solar radiation and convert it into thermal energy (usually to heat water).
Solar Thermal energy systems Systems that collect the sun's energy to produce heat, usually to heat water.
SPD Surge Protector Device
Square Wave Inverter The inverter consists of a DC source, four switches, and the load. The switches are power semiconductors that can carry a large current and withstand a high voltage rating. The switches are turned on and off at a correct sequence, at a certain frequency. The square wave inverter is the simplest and the least expensive to purchase, but it produces the lowest quality of power.
SRCC - Solar Rating and Certification Corporation The Solar Rating and Certification corporation currently administers a certification, rating, and labeling program for solar collectors and a similar program for complete solar water heating systems.
Start-Up The wind speed at which a wind turbine rotor starts to rotate. It does not necessarily produce any power until it reaches cut-in speed.
Starting-Lighting-and-Ignition Battery (SLI) A battery primarily used to start a vehicle and to provide power for lights and accessories. SLI batteries include automotive, deep-cycle and heavy-duty commercial starting batteries
Static Water Level Depth to the water surface in a well under static conditions (not being pumped). May be subject to seasonal changes or lowering due to depletion. Submergence - Applied to submersible pumps: Distance beneath the static water level, at which a pump is set. Synonym: immersion level
Stationary Battery A secondary battery designed for use in a fixed location.
Stator The part of a motor, generator or alternator that does not rotate. In permanent magnet alternators it holds the coils and laminates.
Storage Battery An assembly of identical cells in which the electrochemical action is reversible so that the battery may be recharged by passing a current through the cells in the opposite direction to that of discharge. While many non-storage batteries have a reversible process, only those that are economically rechargeable are classified as storage batteries. Synonym: Accumulator; Secondary Battery. See Secondary Cell.
Storage Cell An electrolytic cell for the generation of electric energy in which the cell after being discharged may be restored to a charged condition by an electric current flowing in a direction opposite the flow of current when the cell discharges. Synonym: Secondary Cell. See Storage Battery.
Stratification - Batteries A condition in which the concentration of acid is greater at the bottom of the battery than at the top. Normally caused by continued undercharging.
Submersible Pump This type of pump is water proof and is submerged in the water. They are usually more expensive. All electrical connections and motor are submerged as well. Examples: Grundfos SQ pump (AC), Dankoff ETA pump DC, fountain pump.
Suction Lift Applied to surface pumps: Vertical distance from the surface of the water in the source, to a pump located above surface pump located above. This distance is limited by physics to around 20 feet at sea level (subtract 1 ft. per 1000 ft. altitude) and should be minimized for best results.
Sulfation The accumulation of lead sulfates on the plates of a lead-acid battery. When enough plate area has sulfated, the battery will not be able to provide enough current and will normally need to be replaced
Surface Pump are not waterproof. They must be located in weatherproof area near the water level, usually a pump pit or pump house. All electrical parts are located away from the water. If the pump is too high above the water level, these pumps will have suction problems that can make the system unreliable or damage the pump. (See suction head & cavatation)Examples: Shurflo pressure pump, Dankoff Flowlight pressure pump, hot water circulator.
Tail A large, flat piece of material used to align a wind turbine rotor correctly into the wind. Usually mounted vertically on the tail boom. Sometimes called a Tail.
Taper Charge A charge regime delivering moderately high-rate charging current when the battery is at a low state of charge and tapering the current to lower rates as the battery becomes more fully charged.
TDH vertical lift + friction loss in piping (see Friction Loss).
Temperature Cutoff A device, such as a thermostat, that senses battery temperature and opens the battery circuit when the temperature reaches a certain point.
temperature-load Check Head Load
THD A measure of how pure or clean a waveform is.
Thermal Runaway A condition whereby a cell on charge or discharge will destroy itself through internal heat generation caused by high overcharge or high rate of discharge or other abusive conditions.
Thermosiphon System A type of solar thermal collector (with water heated directly) in which circulation through the storage loop is provided solely by the heating of the water.
Thin-Film Silicon Most often this is amorphous (non-crystalline) material used to make photovoltaic (PV) cells.
Tip Speed Ratio The ratio of how much faster than the wind speed that the blade tips are moving. Abbreviation TSR.
TL Inverter Transformerless inverters does not use a transformer to step up the output voltage to line voltage and frequency. Instead they use high frequency power boards with IGBT's connected in a bridge. The main advantage is weight management, they are lighter, direct controlled by the inverter logic processor. They do not offer AC to DC direct galvanic isolation. They are UL certified since 2010.
TL Inverters Transformerless inverters does not use a transformer to step up the output voltage to line voltage and frequency. Instead they use high frequency power boards with IGBT's connected in a bridge. The main advantage is weight management, they are lighter, direct controlled by the inverter logic processor. They do not offer AC to DC direct galvanic isolation. They are UL certified since 2010.
Torque Turning force, equal to force times radius. See also Moment.
total dynamic head vertical lift + friction loss in piping (see Friction Loss).
Total Harmonic Distortion A measure of how pure or clean a waveform is.
Tracker In solar electric and solar thermal systems, a device used to track the sun.
Trailing Edge The edge of a blade that faces away from the direction of rotation.
Transformer An electromagnetic device used to convert AC electricity,either to increase or decrease the voltage
Transmission System (Electric) Lines or wires of electricity that transmit electrical energy from points of origin to end users.
Trickle Charging A method of recharging in which a secondary cell is either continuously or intermittently connected to a constant-current supply that maintains the cell in fully charged condition.
TSR The ratio of how much faster than the windspeed that the blade tips are moving. Abbreviation TSR.
Turbine Any machine used to generate rotary mechanical power from the energy of a stream of fluid (such as water, steam, or hot gas) or air (wind power). Turbines convert kinetic energy into mechanical energy.
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Ultra-wide MPPT range These inverters will do maximum-power-point-tracking from 90 through 580 Volts, with the full power output range starting at 120 ... 170 Volts (depending on model).
Uninterruptible power supply A device (likely containing batteries) that stores power for use when conventional power is unavailable (e.g. during a blackout).
Utility-Interactive Inverter An inverter that can function only when tied to the utility grid, and uses the prevailing line-voltage frequency on the utility line as a control parameter to ensure that the PV system’s output is fully synchronized with the utility power.
Utility-Interactive System Any solar PV installation that is connected to and interacting with a utility power line.
Valve-Regulated Lead-acid Battery (VRLA) A lead-acid battery that is sealed with the exception of a one-way valve that opens to the atmosphere when the internal gas pressure in the battery exceeds the atmospheric pressure by a pre-selected amount. VRLA batteries are sometimes called recombinant batteries
Vane A large, flat piece of material used to align a wind turbine rotor correctly into the wind. Usually mounted vertically on the tail boom. Sometimes called a Tail.
Vent A normally sealed mechanism that allows for the controlled escape of gases from within a cell.
Vented Battery A battery in which the gaseous products of electrolysis and evaporation are allowed to escape into the atmosphere as they are generated. These batteries are commonly referred to as flooded batteries
Vertical Lift The vertical distance that water is pumped. This determines the pressure that the pump pushes against. Total vertical lift = vertical lift from the surface of water source up to the discharge in the tank + (in a pressure system) discharge pressure. Synonym: static head. Note: Horizontal distance does NOT add to the vertical lift, except in terms of pipe friction loss. NOR does the volume (weight) of water contained in pipe or tank. Submergence of the pump does NOT add to the vertical lift in the case of a centrifugal type pump. In the case of a positive displacement pump, it may add to the lift somewhat.
Volt The unit of electric potential (intensity) and potential difference. It is also a relation of current to resistance: i.e. 1 volt is the potential difference across a resistance of 1 Ohm when a current of 1 Amp is flowing.
Voltage The measurement of the "intensity" of electricity.
Voltage drop The voltage lost along a length of wire or conductor due to resistance. The voltage drop is calculated using Ohm's Law. Voltage drop is also measured for resistors.
Voltage regulator A device to control the operating voltage of a photovoltaic array.
Voltage, cutoff Voltage at the end of useful discharge. (See Voltage, end-point.)
Voltage, end-point Cell voltage below which the connected equipment will not operate or below which operation is not recommended.
Voltage, nominal Voltage of a fully charged cell when delivering rated current.
VRLA A lead-acid battery that is sealed with the exception of a one-way valve that opens to the atmosphere when the internal gas pressure in the battery exceeds the atmospheric pressure by a pre-selected amount. VRLA batteries are sometimes called recombinant batteries
Wafer Raw material for a solar cell, a thin sheet of crystalline semiconductor material is made by mechanically sawing it from a single-crystal boule or by casting it.
Watt (Electric) The basic unit of electrical power. It is only ever defined in reference to current and intensity-- as in 1 watt equals 1 ampere of current under pressure of 1 volt.
Watt (Thermal) A unit of power in the metric system, expressed as energy per second.
Watthour (Wh) A measure of energy, equal to 1 watt of power used or received by an electric circuit steadily for the duration of 1 hour.
Waveform The shape of a wave that represents a vibration or AC current.
Well Seal Top plate of well casing that provides a sanitary seal and support for the drop pipe and pump.
Wellhead Top of the well, at ground level.
Wet Cell A cell, the electrolyte of which is in liquid form and free to flow and move.
Wind energy Energy from wind motion converted into mechanical energy by the action of a wind turbine driving a generator with its central shaft.
Wind power plant Also called a wind farm, this is a group of turbines interconnected to a common utility system via a system of transformers, distribution lines, and a substation. This term is more common in the United States. Europeans call these generating stations.
Wind turbines Devices consisting of blades that turn a shaft that turns a generator to harvest wind energy and produce electrical power.