Solarimeter calibrations

Our laboratory is equipped with three digital solarimeters SUNMETER (called primary SUNMETER) calibrated. Their calibration has been carried out by comparing their values with the values detected by a primary tool, a Kipp & Zonen CMP22. The calibration process was done by exposure to direct light from the Sun. The output values from the CMP22 pyranometer were read by a digital voltmeter HP Agilent high accuracy and resolution, while the output values of each primary SUNMETER were read by a PC via serial output that each solarmeter SUNMETER has.

When there is a new SUNMETER at the end of the production process, the calibration of the solarmeter is made by direct comparison with a primary SUNMETER solarimeter, and inserting the amplification coefficients such that equalize the irradiation value indicated by the primary.

Calibration process:

You connect a SUNMETER next to 2 primary SUNMETER, through its serial interfaces, to a PC.
The output of each is read and processed by the utility SMcalibrator, like SMconfig but customized to read more SUNMETER contemporary and access to the reserved calibration parameters.
Thought SMcalibrator the correction factor is recalculated to be applied to the SUNMETER that need to be calibrated, in order to bring the output values to coincide with those of primary SUNMETER. This is done for a low value (about 200 W/m) and high value of irradiation (about 1000 W/m).

In fact the firmware on board SUNMETER involves the insertion of two correction coefficients, one for the value of low radiation and one for value of high radiation. Once inserted into the internal memory the correction coefficients, are remade the readings, comparing them with those of primary solarmeters SUNMETER, to ensure they are aligned.

Therefore, thanks to digital technology that each pyranometer SUNMETER has, and that allows it to maintain the full scale analog output to 1250 W/m, each of these digital solarmeters are ready for use, without the need to have conditions and special equipment for the user to adjust the analog input of your data-logger to make reliable readings.

If instead you use a data-logger input RS485 (Modbus), the readings of the logical address of SUNMETER are of course already expressed in W/m.