ISO 9060:2018

Overview

ISO 9060:2018 - Solar energy: Specification and classification of instruments for measuring hemispherical solar and direct solar radiation - defines how pyranometers and pyrheliometers (and related diffusometers) are specified and ranked for use in solar radiation measurement. The standard covers instruments measuring radiation integrated over the spectral range from approximately 0.3 µm to about 3 µm–4 µm. Instruments are classified by the results of indoor or outdoor performance tests (note: ISO 9060:2018 does not prescribe the test procedures).

Key topics and requirements

• Instrument scope: Hemispherical solar radiation (2π sr) and direct solar radiation measurements, plus diffuse measurements using shading devices.
• Device types: Pyranometers for global/hemispherical irradiance; pyrheliometers for direct normal irradiance; diffusometers (pyranometer + shading structure) for diffuse components.
• Spectral range and responsivity: Emphasis on spectral responsivity and spectral error as a characterization metric. The standard accommodates multiple sensor technologies (thermopile and approved photoelectric sensors) provided they meet requirements.
• Classification and accuracy: Instruments are assigned accuracy classes (now named A, B, C) based on performance test outcomes. Additional properties - “spectrally flat” and “fast response” - may be appended when criteria are met.
• Optical geometry: Definitions and guidance on field-of-view and opening half-angles for pyrheliometers (typical opening half-angles range from about 2.5° to 7.5°; a 2.5° opening is recommended for new designs).
• Terminology and metrology: Includes formal terms (global horizontal irradiance, direct solar radiation, diffuse radiation), accuracy class definitions, and metrological concepts (offset correction, correction factor, tolerance/acceptance intervals).

Applications and users

ISO 9060:2018 is essential for:

• Solar resource assessment and meteorology - ensuring comparable irradiance data.
• Performance testing and certification of PV, CSP, and solar thermal systems.
• Manufacturers and testing laboratories - for product specification and quality claims.
• Procurement and tendering processes - providing objective instrument selection criteria.
• Research institutions and simulation teams - for selecting instrumentation that meets application-specific accuracy and response requirements.

Benefits include consistent data quality, clearer procurement specifications, and improved comparability of solar radiation measurements across projects and regions.

Related standards

• ISO 9846 - referenced for shading disk tracking and design (diffuse radiation measurement).
• ISO/TC 180 (Solar energy) - technical committee responsible for this work.

Keywords: ISO 9060:2018, pyranometer, pyrheliometer, solar radiation measurement, hemispherical solar radiation, direct normal irradiance, spectral responsivity, instrument classification, solar energy instrumentation.