Photovoltaic Conversion Efficiency Terms +

(solar electricity technical terms applying to electricity, power generation, concentrating solar power, or CSP, solar heating, solar lighting, and solar electricity)

uninterruptible power supply
The designation of a power supply providing continuous uninterruptible service.

The uninterruptible power supply will contain batteries.

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 photovoltaic system's output is fully synchronized with the utility power.
vacuum evaporation
The deposition of thin films of semiconductor material by the evaporation of elemental sources in a vacuum.
vacuum zero
The energy of an electron at rest in empty space; used as a reference level in energy band diagrams.
valence band
The highest energy band in a semiconductor that can be filled with electrons.
valence level energy/valence state; bound state
Energy content of an electron in orbit about an atomic nucleus.
varistor
A variable resistor consisting of a two-electrode resistor made of semiconductor material and having voltage-dependent nonlinear resistance that drops with an increase in applied voltage.

It can be used to protect sensitive equipment from power spikes or lightning strikes by shunting the energy to the ground.

vented cell
A battery designed with a vent mechanism to expel gases generated during charging.
vertical multijunction (VMJ) cell; multiple junction cell
A compound cell made of different semiconductor materials in layers, one above the other.

Sunlight entering the top passes through successive cell barriers, each of which converts a separate portion of the spectrum into electricity, thus achieving greater total conversion efficiency of the incident light.

volt (V)
A unit of electrical force equal to that amount of electromotive force that will cause a steady current of one ampere to flow through a resistance of one ohm.
voltage
The amount of electromotive force, measured in volts, that exists between two points.
voltage at maximum power; Vmp
The voltage at which maximum power is available from a photovoltaic module.
voltage protection
Many inverters have sensing circuits that will disconnect the unit from the battery if input voltage limits are exceeded.
voltage regulation
This indicates the variability in the output voltage.

Some loads will not tolerate voltage variations greater than a few percent.

wafer
A thin sheet of semiconductor (photovoltaic material) made by cutting it from a single crystal or ingot.
—The information for the entries in this unit were compiled primarily from data
provided in the following source:

"U.S. Department of Energy, Energy Efficiency and Renewable Energy"
consisting of definitions of many important terms having to do with electricity,
power generation, concentrating solar power (CSP), solar heating, solar lighting,
and solar electricity, also known as photovoltaic (PV).

Information was also compiled from the

Academic Press Dictionary of Science and Technology; Edited by Christopher Morris;
Academic Press; Harcourt Brace Jovanovich, Publishers; New York; 1992;
as well as,
McGraw-Hill Dictionary of Scientific and Technical Terms, 4th edition;
Sybil P. Parker, editor in chief; McGraw-Hill, Inc.; 1989.

Index of additional Scientific and Technological Topics.