ASTM E816 Pyrheliometer Calibration for Solar Radiation Testing
ASTM E816-05 test method covers two types of calibrations. One is the calibration of a secondary reference pyrheliometer, and the second is the transfer of the calibration. This method serves as a source of calibration procedures and provides details about the calibration hierarchy. It is especially used for reference pyrheliometers with field angles of 5 to 6 degrees.
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- Overview
- Scope, Applications, and Benefits
- Test Process
- Specifications
- Instrumentation
- Results and Deliverables
Overview
ASTM E 816 pyrheliometer calibration testing is a standardized test method for the calibration of pyrheliometers through direct comparisons with reference pyrheliometers under specified solar radiation conditions, where calibration factors for direct normal solar irradiance measurement instruments can be established using defined measurement procedures. ASTM E 816 specifies the measurement procedures, reference pyrheliometer requirements, and methods for determining calibration factors required to ensure accurate calibration of pyrheliometers, enabling solar energy engineers, meteorologists, and calibration experts to use accurate calibration data to measure solar radiation with high accuracy.
Scope, Applications, and Benefits
Scope
ASTM E816 standard specifies the calibration method for pyrheliometers by simultaneously measuring the direct normal solar irradiance with the instrument under calibration and a reference pyrheliometer traceable to the world radiometric reference, and calculating the calibration factor from comparisons of simultaneous irradiance measurements.
ASTM E 816 pyrheliometer calibration testing evaluates:
- Calibration factor determination for pyrheliometers by reference comparison under solar radiation
- Traceability of pyrheliometer calibration to World Radiometric Reference standards
- Instrument response consistency across defined solar elevation and atmospheric conditions
- Calibration uncertainty assessment for direct normal solar irradiance measurement instruments
- Compliance against defined pyrheliometer calibration accuracy requirements for solar measurement programs
Applications
- Solar energy resource assessment programs requiring traceable solar irradiance measurement
- Photovoltaic and concentrating solar power plant performance monitoring instrument calibration
- Meteorological station and weather monitoring pyrheliometer calibration programs
- Solar radiation research and atmospheric science instrument calibration requirements
- Calibration laboratories requiring ASTM E 816 pyrheliometer calibration test data
Benefits
- Provides traceable pyrheliometer calibration data for solar irradiance measurement accuracy
- Supports solar energy measurement standard compliance and instrument assessment programs
- Identifies pyrheliometer calibration deficiencies before solar radiation measurement programs
- Delivers traceable calibration records for engineering and regulatory submissions
- Reduces measurement risk by verifying pyrheliometer calibration early in instrument assessment
Test Process
Instrument Setup
Pyrheliometer and reference instrument mounted on solar tracker under defined clear sky conditions.
1Simultaneous Irradiance Measurement
Direct normal solar irradiance measured simultaneously by reference and test pyrheliometers.
2Calibration Factor Calculation
Calibration factor calculated from ratio of reference to test instrument irradiance measurements.
3Data Analysis & Reporting
Calibration factor and uncertainty assessed against defined criteria for test compliance result.
4Technical Specifications
| Parameter | Details |
|---|---|
| Applicable Instruments | Pyrheliometers for direct normal solar irradiance measurement and calibration |
| Reference Instrument | Reference pyrheliometer traceable to World Radiometric Reference standards |
| Measurement Conditions | Defined clear sky and solar elevation conditions per ASTM E 816 requirements |
| Measured Parameters | Direct normal solar irradiance ratio and calculated calibration factor |
| Measured Outputs | Calibration factor, measurement uncertainty, irradiance data, and test compliance result |
Instrumentation Used for Testing
- Reference pyrheliometer traceable to the World Radiometric Reference for comparison measurement
- Solar tracker system for precise sun-pointing alignment during calibration
- Data acquisition system for simultaneous irradiance signal recording
- Calibrated signal conditioning and measurement electronics for pyrheliometer output
- Atmospheric condition monitoring instrumentation for calibration condition assessment
- Data reporting and calibration factor calculation system
Results and Deliverables
- Simultaneous irradiance measurement data for reference and test pyrheliometer instruments
- Calculated calibration factor and measurement uncertainty per ASTM E 816 procedures
- Atmospheric condition records during calibration measurement sessions
- Test compliance result assessed against defined pyrheliometer calibration accuracy requirements
- ASTM E 816 pyrheliometer calibration report
Frequently Asked Questions
ASTM E816-05 outlines steps for calibrating pyrheliometers. It does this by comparing their readings with those of reference pyrheliometers. This process guarantees precise measurement of direct solar irradiance in controlled atmospheric and operational conditions.
Precise solar irradiance measurement is crucial for solar energy research and meteorology. ASTM E816-05 ensures instruments deliver dependable data for assessing solar resources, system performance, and environmental studies.
ASTM E816-05 is used to calibrate pyrheliometers. These instruments measure direct beam solar radiation. Pyrheliometers are commonly used in solar energy systems, meteorological stations, and atmospheric research.
ASTM E816-05 calibration involves comparing the readings of a test pyrheliometer with those of a reference instrument under the same solar conditions. Correction factors are calculated to ensure that the measurements are accurate.
ASTM E816-05 calibration relies on stable atmospheric conditions and the accuracy of reference instruments. Results can change because of environmental shifts, alignment mistakes, or instrument drift over time.
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