v      System for simulating sun light

v      Sun light has a spectrum of wavelengths which includes:

       UV

       Visible

       Infra red

Sun Light Characteristics

v      Spectrum of sunlight at the earth’s surface is different than sun light in space.

v      This is due to some wavelengths being absorbed by the atmosphere (air mass).

v      The spectrum of sun light also varies depending on the location on earth’s surface.

v      The spectrum of sun light also varies depending on the time of the day.

Sun Light Characteristics

v      At noon time sun is directly overhead, hence the distance the light has to travel through atmosphere (air mass) to reach the earth’s surface is the shortest. 

v      At any other time the distance the light has to travel through atmosphere (air mass) to reach the earth’s surface is  always longer than at noon.

v      In addition, the spectrum of sun light reaching at any given time and point on the earth’s surface varies with the time of the year.

Standards For Solar Simulators

v      As a result of all these variations, it was necessary to define a standard.

v      ASTM has defined standards for the USA.

v      IEC has defined standards for Europe.

v      JIS has defined standards for Japan.

v      All of these standards are almost identical.

v      Sun light spectrum in space is defined as air mass 0 (AM0).

v      Sun light spectrum reaching the earth’s surface with the sun directly overhead is defined as air mass 1 (AM1).

v      Sun light spectrum reaching the earth’s surface when the sun’s vector is 48.2 degrees form the vertical, is defined as air mass 1.5 (AM1.5).

v      Sun light spectrum reaching the earth’s surface when the sun’s vector is 60.1 degrees form the vertical, is defined as air mass 2.0 (AM2.0).

v      In addition to defining air mass standards, standards are defined for the class of Solar Simulator Systems.

v      There are three classes of systems defined.

v      Class A – best classification.

v      Class B – better classification.

v      Class C – good classification.

v      Each class defines properties of the light beam and how well it matches the sun light.

v      Each class defines the following properties of the light beam

v      Non-uniformity of Light Beam

v      Temporal instability of Light Beam

v      Total irradiance within  30 degree field of view *

v      Spectral match to sun light

* No longer included in the ASTM standard as of 2006

ASTM E927 Standard

ASTM E927 Standard

ASTM E927 Standard

Solar Simulator Definition

v      A solar simulator must meet one of the three classifications.

v      A solar simulator must meet all the requirements of its designated class.

v      A system that does not meet any of the classifications:

        Is NOT a solar simulator.

        Should be called a light source.

v      Two types of solar simulators:

       Continuous or steady state.

       Flashing.

v      Steady state solar simulators – max. Area of illumination up to 400mm x 400mm.

       Generally used for cell or small panel testing.

v      Flashing solar simulators – max. Area of illumination up to 2m x 2m.

       Generally used for panel testing, can be used for cell testing.

Class AAA Cell Tester Models

       CT50   50mm x 50mm area of illumination

       CT80   80mm x 80mm area of illumination

       CT100 100mm x 100mm area of illumination

       CT150 150mm x 150mm area of illumination

       CT200 200mm x 200mm area of illumination

       CT400 400mm x 400mm area of illumination

Class AAA Solar Simulator Models

       SS50    50mm x 50mm area of illumination

       SS80    80mm x 80mm area of illumination

       SS100  100mm x 100mm area of illumination

       SS150  150mm x 150mm area of illumination

       SS200  200mm x 200mm area of illumination

       SS400  400mm x 400mm area of illumination