Solar Glossary: [ A-B ] [C ] [ D-F ] [ G-H ] [ I-N ] [ O-P ] [ Q-R ] [ S ] [ T-Z ]

The U.S. Department of Energy has an extensive glossary of energy related terms including the definitive explanations of the basic solar energy terms listed below.

Solar Glossary A - B

Absorber

The component of a solar thermal collector that absorbs solar radiation and converts it to heat, or, as in a solar photovoltaic device, the material that readily absorbs photons to generate charge carriers (free electrons or holes).

Absorption Coefficient

In reference to a solar energy conversion devices, the degree to which a substance will absorb solar energy. In a solar photovoltaic device, the factor by which photons are absorbed as they travel a unit distance through a material.

Absorptivity

In a solar thermal system, the ratio of solar energy striking the absorber that is absorbed by the absorber to that of solar energy striking a black body (perfect absorber) at the same temperature. The absorptivity of a material is numerically equal to its emissivity.

 

Active Solar Heater

A solar water or space-heating system that use pumps or fans to circulate the fluid (water or heat-transfer fluid like diluted antifreeze) from the solar collectors to a storage tank subsystem.

Air Collector

In solar heating systems, a type of solar collector in which air is heated in the collector.

Angle of Incidence

In reference to solar energy systems, the angle at which direct sunlight strikes a surface; the angle between the direction of the sun and the perpendicular to the surface. Sunlight with an incident angle of 90 degrees tends to be absorbed, while lower angles tend to be reflected.

Angle of Inclination

In reference to solar energy systems, the angle that a solar collector is positioned above horizontal.

Annual Load Fraction

That fraction of annual energy demand supplied by a solar system.

Annual Solar Savings

The annual solar savings of a solar building is the energy savings attributable to a solar feature relative to the energy requirements of a non-solar building.

Antifreeze Solution

A fluid, such as methanol or ethylene glycol, added to vehicle engine coolant, or used in solar heating system heat transfer fluids, to protect the systems from freezing.

Aperture

An opening; in solar collectors, the area through which solar radiation is admitted and directed to the absorber.

Apparent Day

A solar day; an interval between successive transits of the sun's center across an observer's meridian; the time thus measured is not equal to clock time.

Array (Solar)

Any number of solar photovoltaic modules or solar thermal collectors or reflectors connected together to provide electrical or thermal energy.

Azimuth (Solar)

The angle between true south and the point on the horizon directly below the sun.

Batch Heater

This simple passive solar hot water system consists of one or more storage tanks placed in an insulated box that has a glazed side facing the sun. A batch heater is mounted on the ground or on the roof (make sure your roof structure is strong enough to support it). Some batch heaters use "selective" surfaces on the tank(s). These surfaces absorb sun well but inhibit radiative loss. Also known as bread box systems or integral collector storage systems.

Beam Radiation

Solar radiation that is not scattered by dust or water droplets.

Boron

The chemical element commonly used as the dopant in solar photovoltaic device or cell material.

Bread Box System

This simple passive solar hot water system consists of one or more storage tanks placed in an insulated box that has a glazed side facing the sun. A bread box system is mounted on the ground or on the roof (make sure your roof structure is strong enough to support it). Some systems use "selective" surfaces on the tank(s). These surfaces absorb sun well but inhibit radiative loss. Also known as batch heaters or integral collector storage systems.

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