History

The weather measurement station on the roof of building 119 at the Lyngby campus of the Technical University of Denmark (DTU) has been in operation since April 1989. It was initially established as a measurement facility for climate parameters, especially for active and passive solar heating systems. The measured parameters were the air temperature, air relative humidity, wind speed and direction, global horizontal irradiance (GHI), direct normal irradiance (DNI), and diffuse horizontal irradiance (DHI). The DNI was measured using a pyrheliometer mounted on an Eppley tracker. The DHI was measured using a shadowring and using a shading disk mounted on the Eppley tracker that screened off the beam radiation from the sun disk. Data logging was done using a DOS-based computer without an internet connection. However, the station required high maintenance in order to perform reliable measurements, particularly the adjustment and maintenance of the tracker and the shadowring. Additionally, it was no longer possible to get service and find spare parts for the DOS-based data-logging system. Consequently, a major upgrade was performed in 2014 in order to reduce the maintenance workload and improve the data quality.

The upgrade was in terms of both hardware and software. The hardware was from National Instruments and comprised a CompactRIO control and monitoring system (i.e., a stand-alone computer with internet access) with a number of input/output modules. A SOLYS 2 tracker from Kipp and Zonen replaced the old Eppley tracker. This tracker had an integrated GPS receiver that automatically determined its location and time. Additionally, the tracker was equipped with a solar sensor from Kipp and Zonen in order to fine-tune the tracker. A CMP 11 pyranometer from Kipp and Zonen was mounted on the tracker to measure the diffuse radiation, and a CHP 1 pyrheliometer was mounted to measure the direct normal irradiance. Regarding software, a database was created on the university’s FTP server, and a website was developed that enabled users to download the data freely.

The aforementioned setup was in operation until 2024, when a new station upgrade was done, bringing the station to its current state. The major upgrade carried out in 2024 is documented in this report.

Reports concerning previous upgrades of the station can be found below:

• Availability of high-quality weather data measurements (2017)

• Upgrade and extension of the climate station at DTU Byg (2014)

• Solar monitoring station (1994)