EKO INSTRUMENTS CO., LTD. - Pyranometer MS-60/60S - Instruction Manual Ver. 4
Pg. 19
3) MS-60S [0-1VOutput]
a.
Setup the measurement range on the measuring device.
Setup the measurement range on the measuring device.
If the measurement range can be selected, chose the range which can measure between 0 to 1V
accurately.
Same for installing either in slope or horizontally, maximum solar irradiance is considered at
1,400W/m
2
, thus it is setup [default] so that the output of MS-60S [0-1V conversion] should be
1,600W/m
2
at 1V.
b.
Calculate the Solar Irradiance [W/m
2
]
When the solar irradiance voltage value is
V
[V], the solar irradiance
I
[W/m
2
] can be determined
by the following formula:
I
[W/m
2
] =
Sv
=1/1,600 (default setting)
4) MS-60S [Modbus RTU Output, SDI-12 Output]
When using the digital output (Modbus or SDI-12) by default the irradiance conversion is performed
on-board and is one of the measurement parameter within the data string.
2. Integration of Measurement Value:
In continuous operation mode the pyranometer is usually connected to a programmable data logger system.
Hence, sampling rates and data reduction methods can be defined right at the beginning of the data
acquisition process.
The response time that is given in the specifications of the EKO pyranometers states the amount of time,
which is necessary to reach 95% of the final measurement value. It is also possible to define a 63.2%
response [which is equal to 1-1/e]. This time constant, represented by
the symbol τ, is 3 times smaller than
the values specified by EKO. The recommended
[1]
sampling rate for pyranometers is smaller than τ. So, for
EKO pyranometers, the sampling rates that have to be programmed in the data logger systems should not
exceed the values as given in Table 7-1.
Performing averaging and/or integration of measurement data can be meaningful to, e.g., reduce the data
volume or to meet application-specific requirement. Note that shorter sampling rates allow to use shorter
averaging/integration times [example for MS-60: <10 second sampling rate, 1 minute averaging period]. It
could also be meaningful to store not only average values, but to keep track of all statistical values during the
averaging period, namely: average, integral, minimum and maximum values, and standard deviation.
As a general recommendation, the averaging/integration period should be as short as possible, but long
enough to reduce the data volume to store the processed data safely.
[1]
“Guide to Meteorological Instruments and Methods of Observation”, WMO reference document No. 8.
Examples:
The total daily radiant energy in Joule per meter squared [J/m
2
] is obtained by integrating the solar irradiance
over time. To calculate the total daily radiant energy in Joule per meter square [J/m
2
], multiply the averaged
solar irradiance
I
[W/m
2
] by the averaging interval period [s]. Then sum-up the total data number [n] of
averaged data points in one day.
Its physical unit is expressed with [J/m
2
] and can be calculated with J = W
・
S
V
[V]
Sv
[V/W
･
m
-2
]