EKO MS-80 - Page 30

EKO INSTRUMENTS CO., LTD. - Pyranometer MS-80/80S/80U - Instruction Manual Ver. 1
Pg. 29
3. Irradiance conversion
For MS-80, MS-80U with analog mV output the global solar Irradiance [W/m2] can be determined by
measuring the output voltage [mV] divided by the individual sensor sensitivity [μV/W・m-2]. The maximum
output voltage can be calculated by multiplying the maximum solar irradiance with the calibration factor [e.g.
when the sensitivity of the MS-80 pyranometer is about 10μV/W・m-2 or 0.010mV/W・m-2, the maximum
output voltage is about 1,400W/m2 times 0.010mV/W・m-2 = 14mV].
Analog output
The solar irradiance in Watts per meter squared [W/m
2
] is obtained when the output voltage E [μV] is divided
by the sensitivity of the pyranometer S [μV/W・m
-2
]. This calculation is expressed by the following formula:
I [W/m
2
] =
*The sensitivity S for the pyranometer is stated on the calibration certificate and the product label.
4-20mA output
If the measurement range can be selected on the data logger, select the measurement range, which can
accurately measure the signal within a range of 4 to 20mA. The output for the MS-80S is set to be 1,600W/m
2
at 20mA.
When the solar irradiance current value is A [mA], the solar irradiance I [W/m
2
] can be determined by the
following formula:
I [W/m
2
] = (A [mA] - 4) x (1600 / 16)
Note: When the range setting is changed for example 4-20 mA = 0-2000 [W/m
2
]
I [W/m
2
] = (A [mA] - 4) x (2000 /16)
0-1V output
If the measurement range can be selected on the data logger, select the measurement range, which can
accurately measure the signal within a range of 0 to 1V. The output for the MS-80S is set to be 1,600W/ m
2
at
1V.
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
] = V [V] x 1600
MS-80S [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 parameters within the data string.
E [
μ
V]
S [μV/W
･
m
-2
]