Article: Solar Irradiance Measurements

Irradiance is the amount of energy at each wavelength emitted from a radiant sample. Absolute irradiance is the measure of light in absolute terms. Relative irradiance is a comparison of the fraction of energy the sample emits and the energy the sampling system collects from a lamp with a blackbody energy distribution.

Measurement of absolute solar irradiance is relevant in a number of applications: monitoring the sunlight itself, perhaps in the context of its relationship to greenhouse gases in the atmosphere; investigating the effect of solar radiation on ecological systems and crops; and evaluating the effect of UV sunlight on our skin and eyes.

Solar radiation includes spectral response across the broad UV-NIR region. We offer a number of spectrometer options that will measure solar irradiance over various portions of the solar spectrum between 200-1100 nm. A spectrometer now in development will combine both UV-Vis CCD-array and NIR InGaAs-array detectors in the same unit, extending the possible measurement range considerably.