Glossary

P

PARALLEL CONNECTION

A wiring configuration used to increase current (amperage). Parallel wiring is positive to positive (+ to +) and negative to negative (- to -). Opposite of a series connection.

PEAK POWER POINT

Operating point of the I-V (current-voltage) curve for a Photovoltaic cell or module where the product of the current value times the voltage value is a maximum.

PEAK WATTS

The measurement of electricity produced by a solar generator at noon on a sunny day, under predetermined standard conditions

PHOTON

The actual (physical) particle unit of light, as the electron is of electric charge and the atom and molecule are of matter. Light has both wave properties and particle properties. Violet light has relatively short wavelength and higher energy in its photons; red light has longer wavelength, lower-energy photons. The wavelength and/or energy spectrum of the sun extends in both directions beyond the visible range of light, of course, and the silicon module solar cell can capture some energy in both of these invisible zones. Photons not captured by the cell are either reflected or converted to heat in the solar array.

PHOTOVOLTAIC CELL

A device composed of specially prepared semiconductor material or material combinations exhibiting the ability to convert incident solar energy directly into electrical energy.

PHOTOVOLTAIC EFFECT

The phenomenon that occurs when photons, the “particles” in a beam of light, knock electrons loose from the atoms they strike. When this property of light is combined with the properties of semiconductors, electrons flow in one direction across a junction, setting up a voltage. With the addition of circuitry, current will flow and electric power will be available.

PHOTOVOLTAIC SYSTEM

An installed aggregate of solar arrays generating power for a given application.

POWER CONDITIONER

The electrical equipment used to convert power from a photovoltaic array into a form suitable for subsequent use. Loosely, a collective term for inverter, transformer, voltage regulator and other power controls.

R

RENEWABLE ENERGY

Flows of energy that are regenerative or virtually inexhaustible. Most commonly includes solar (electric and thermal), biomass, geothermal, wind, tidal, wave, and hydro power sources.

S

SEMICONDUCTOR

A material such as silicon, which has a crystalline structure that will allow current to flow under certain conditions. Semiconductors are usually less conductive than metals but not an insulator like rubber.

SERIES CONNECTION

A wiring configuration used to increase voltage. Series wiring is positive to negative (+ to -) or negative to positive (- to +). Opposite of parallel connection.

SILICON

A non-metallic element, that when specially treated, is sensitive to light and capable of transforming light into electricity. Silicon is the basic material of most beach sand, and is the raw material used to manufacture most photovoltaic cells.

SINGLE-CRYSTAL STRUCTURE

A material having a crystalline structure such that a repeatable or periodic molecular pattern exists in all three dimensions.

SOLAR CELL

The basic photovoltaic device which generates electricity when exposed to sunlight.

SOLAR PANEL

A collection of solar modules connected in series, in parallel, or in series- parallel combination to provide greater voltage, current, or power than can be furnished by a single solar module. Solar panels can be provided to furnish any desired voltage, current, or power. They are made up as a complete assembly. Larger collections of solar panels are usually called solar arrays.

STAND-ALONE SYSTEM (SA)

A system which operates independently of the utility lines. It may draw supplementary power from the utility but is not capable of providing power to the utility.

STORAGE BATTERY

A device capable of transforming energy from electric to chemical form and vice versa. The reactions are almost completely reversible. During discharge, chemical energy is converted to electric energy and is consumed in an external circuit or apparatus.

T

TILT ANGLE

A fixed angle measured from the horizontal to which a solar array is tilted. The tilt angle is chosen to maximize the array output. Depending upon latitude, season and time of day this angle will vary.

TRACKING ARRAY

An array that is mounted on a movable structure that attempts to follow the path of the sun. Some tracking arrays are single axis while others are dual.