solartype

Solartype is a term used in solar resource assessment and solar energy design to describe a concise descriptor of the spectral and temporal quality of sunlight at a given location and time. The concept treats sunlight as a resource that varies in spectrum, intensity, and variability, and it provides a framework for comparing or selecting solar technologies and materials.

Definition and categories: In practice, solartype is often summarized by a small set of categories or a continuous index derived from measurements of spectral power distribution, irradiance, and irradiance variability. Common practice uses three broad solartypes (A, B and C) representing low, medium, and high short-wave content and temporal variability, with A associated with cloudier or sunrise/sunset conditions, B with typical clear-sky mid-day, and C with high-frequency fluctuations due to weather fronts or aerosol content. The precise thresholds depend on the study and standardization efforts and are not universally fixed.

Measurement and computation: Solartype is computed from field measurements using spectroradiometers or derived from satellite or model data. Metrics include spectral power distribution, correlated color temperature, total solar irradiance, and the coefficient of variation of irradiance. This helps in selecting photovoltaic technologies (for example, crystalline silicon versus thin-film), or design choices for building integration and shading devices.

Applications and limitations: It informs architectural planning, agricultural planning, and solar thermal system sizing. The lack of universal standards means solartype remains context dependent and is sensitive to atmospheric conditions and time of day. Ongoing work focuses on standardization and integration with solar forecasting tools.

See also: Solar spectrum, Solar irradiance, Photovoltaics, Building-integrated photovoltaics.