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As a homeowner of a solar system, you might want to know these basic terms or at least be able to look up the terms easily.
Ampere (A) or Amp The unit for the electric current; the flow of electrons. One amp is 1 coulomb passing in one second. One amp is produced by an electric force of 1 volt acting across a resistance of 1 ohm.
Ampere Hour (Ah) Quantity of electricity or measure of charge. How many amps of flow or which can be provided over a one hour period. Deep cycle batteries used in solar power systems are rated in Ah (amp-hour).
Azimuth Angle between the north direction and the projection of the surface normal into the horizontal plane; measured clockwise from north. As applied to the PV array, 180 degree azimuth means the array faces due south.
Balance of Systems (BOS) The parts of the photovoltaic system other than the PV array such as the switches, controls, meters, power-conditioning equipment, supporting structure for the array and storage components, if any. The cost of land may or may not be included when comparing total system cost with the cost of other energy sources.
Cell The basic unit of a photovoltaic panel or battery.
Cell Junction The area of immediate contact between two layers (positive and negative) of a photovoltaic cell. The junction lies at the center of the cell barrier or depletion zone.
Deep Discharge Discharging a battery to 20-percent or less of its full charge.
Electric Current A flow of electrons; electricity, amps.
Embodied Energy The quantity of energy required to manufacture a product and supply it to the point of use. It is the sum total of energy necessary from the raw material extraction to the manufacture to the transportation and installation of a product or service
Final Annual Yield
Grid-Connected PV Power Systems aka On-the-Grid
Grid- Installed power: Power delivered by a photovoltaic module or a photovoltaic array, under standard test conditions (irradiance of 1 000 W/m², cell junction temperature of 25°C, AM1,5 solar spectrum). Also said STC output power. Unit: W.
I-V Curve: A graphical presentation of the current versus the voltage from a photovoltaic cell as the load is increased from the short circuit (no load) condition to the open circuit (maximum voltage) condition. The shape of the curve characterizes cell performance.
Lifetime of Battery
Maximum Power Point Tracking (MPPT)
Open-Circuit Voltage (Voc)
Peak Load or Peak Demand
Performance Ratio Ratio of the final annual (monthly, daily) yield to the reference annual (monthly, daily) yield, where the reference annual (monthly, daily) yield is the theoretically annual (monthly, daily) available energy per kilowatt of installed power.
Photovoltaic Cell aka Solar Cell
Photovoltaic Power System
PV: Abbreviation of photovoltaic or photovoltaics .
PVPS: Abbreviation of photovoltaic power system(s).
Semiconductor Any material that has a limited capacity for conducting an electric current. Generally falls between a metal and an insulator in conductivity. Certain semiconductors, including silicon, gallium arsenide, copper indium diselenide, and cadmium telluride, are uniquely suited to the photovoltaic conversion process.
Short Circuit Current (Isc)
Sine Wave inverter
Solar Cell aka Photovoltaic Cell
Solar Thermal Electric
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.
Stand-Alone PV Power Systems aka Off-the-Grid This is a system that is not connected to the utility grid and must use a means to store the electricity produced.
Standard Test Conditions (STC)
State of Charge (SOC) The available capacity remaining in the battery, expressed as a percentage of the rated capacity.
Substrate The physical material upon which a photovoltaic cell is made.
Superstrate The covering on the sun side of a PV module. It provides protection for the PV materials from impact and environmental degradation while allowing maximum transmission of the appropriate wavelengths of the solar spectrum.
Thin Film A layer of semiconductor material, such as copper indium diselenide, cadmium telluride, gallium arsenide, or amorphous silicon, a few microns or less in thickness, used to make photovoltaic cells. Commonly called amorphous.
Total Internal Reflection
Tracking Array PV array that follows the path of the sun to maximize the solar radiation incident on the PV surface. The two most common orientations are (1) one axis where the array tracks the sun east to west and (2) two-axis tracking where the array points directly at the sun at all times. Tracking arrays use both the direct and diffuse sunlight. Two-axis tracking arrays capture the maximum possible daily energy. Typically, a single axis tracker will give you 15% to 25% more power per day, and dual axis tracking will add about 5% to that. Depends somewhat on latitude and
Transformer Steps AC voltage up or down, depending on the application.
VDC Volts direct current (DC)
Voltage at Maximum Power (Vmp) The voltage at which maximum power is available from a module.
Wafer A thin sheet of semiconductor material made by mechanically sawing it from a single-crystal or multi-crystal ingot or casting.
Watt-hour (Wh) See Kilowatt-hour.
Waveform The shape of the curve graphically representing the change in the AC signal voltage and current amplitude, with respect to time.
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