Glossary: I

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The constant current (I) discharge rate that can be maintain for 10 hours (10). For example .3 x I10 = 30% of the I10 constant current discharge rate

Incandescent Light

An electric lamp that is evacuated or filled with an inert gas and contains a filament (commonly tungsten). The filament emits visible light when heated to extreme temperatures by electric current through it. Incandescent light bulbs are one of the most inefficient ways to light a home. They produce a great deal of heat along with the light, and use three to four times as much energy for the same light output as compact fluorescent light bulbs.

Induction Motor (AC)

A type of electric motor that requires a high surge to start, and a stable voltage supply, making it a challenge to run using a solar-electric system.

Input Line Cord

The covered bundle of wiring connected to the input terminals of the UPS. The end of the cord not connected to the UPS is connected, via an input plug, to an AC utility outlet supplying power to the UPS.

Input Plug

Connected to the end of the input line cord. To be plugged into an AC utility outlet receptacle.


The amount of sunlight reaching an area. Usually expressed in watts per square meter.


In a hydro system, the structure that receives the water and feeds it into the penstock (pipeline). Usually incorporates screening or filtering to keep debris and aquatic life out of the system.

Internal Bypass

UPS circuitry which provides a redundant power path is referred to as an Internal Bypass. If there is an internal UPS fault, the connected load will still be supplied with unconditioned utility power.


A device that converts electricity from direct current (DC) power into alternating current (AC) power.


An electrically charged particle or molecule.


Short Circuit Current: The current between two points in a circuit when the points are electrically connected with a conductor with essentially zero resistance. Normally applied to PV modules, which can be short circuited safely because they are limited current devices.


The separation - often through the use of an isolation transformer - of one section of a system in order to avoid undesired electrical influences that may occur in another section.

Isolation Transformer

An Isolation Transformer uses isolated windings that physically separate the primary and secondary windings. Although the two windings are physically disconnected, the magnetic field in the windings of the primary creates (induces) electrical power in the secondary winding. In this way the electrical power available at the input can be transferred to the output. An isolation transformer does not transfer unwanted noise and transients from the input circuit to the output windings. This attenuation, or reduction in amplitude, could be as high as one million to one.

Iv Curve

The graphical representation of the current versus the voltage of a photovoltaic cell, module, or array as the load is increased from zero voltage to maximum voltage, under standard test conditions.