EKO INSTRUMENTS CO., LTD. - Pyranometer MS-60/60S - Instruction Manual Ver. 4
Pg. 22
6 - 2 . C a l i b r a t i o n a n d M e a s u r e m e n t U n c e r ta i n t y
It is recommended to recalibrate MS-60 pyranometer once every 2 years in order to verify the good quality of
the solar radiation measurements. Below explains about the calibration methods of EKO pyranometers and
the calibration uncertainty. For further information about recalibration and maintenance procedures, please
contact EKO or find on the EKO website [http://eko-eu.com].
EKO is a unique manufacturer who can offer calibration service for pyranometers and pyrheliometers
in-house. Based on the applied calibration methods EKO provides the best quality solar sensor calibrations
compliant to the international standards defined by ISO/IEC17025 / 9847 [Indoor method] and ISO9059
[Outdoor method] [Certification: L13-94-R2 /
1. Calibration Method
MS-60 is calibrated indoors according to the ISO 9847 international standard against a 1000W/m
2
AAA class
solar simulator radiation source and designated calibration facility.
Indoor Calibration Procedure
As the calibration procedure, 1] place both reference and production pyranometers in the center of the light in
horizontal position at the same distance from the solar simulator; 2] alternatively irradiate the reference and
production pyranometers with 1000W/m
2
continuously and measure the output [mV] from each pyranometer
for a specified time; 3] From the reference output [mV] and sensitivity [
μV//W/m
2
], calculate the irradiance
[W/m
2
]; 4] finally the sensitivity [
μV/W/m
2
] value is calculated by division of the pyranometer output [mV] and
reference irradiance [W/m
2
].
Measurement Uncertainty of Indoor Calibration
The calibration uncertainty becomes smaller as the calibration is performed with a constant ambient
temperature and using a solar simulator with stable light source; hence the repeatability of indoor calibration
method is better than 99%.
The expanded calibration uncertainty depends on the pyranometer model, and its result is stated on the
calibration certificate.
The pyranometer calibration uncertainty is determined with consideration of uncertainty of the reference
pyranometer and maximum variation of incident light during the measurement of production pyranometer and
reference pyranometer.
2. Calibration Traceability
The Internal reference pyranometer maintained at EKO is traceable to the absolute cavity pyrheliometer
which is directly compared against the WRR [World Radiometric Reference] Primary Standard [Absolute
Cavity] maintained at PMOD [Davos, Switzerland]. The logger system used for the calibration measurement
is traceable to JEMIC [Japan Electric Meters Inspection Cooperation].
Internal reference pyranometer is calibrated directly compared against the pyrheliometer, which is measured
against the EKO absolute cavity, and 2 units of internal reference pyranometers by Shading Method [[A New
Method for Calibrating Reference and Field Pyranometers [1995]] Bruce W Forgan] every one year.
EKO absolute cavity is directly traceable to WRR by comparing against WRR every 5 years.