Impact of a solar farm on temperature and radiation measurements at Groningen Airport Eelde in the Netherlands

In the summer of 2019 a 20 hectares solar farm was installed on Groningen Airport Eelde at a distance of about 30 m from the operational KNMI measurement site at the Groningen Airport. The solar farm has another surface roughness and a different energy balance than the surrounding areas and an impact of the farm on the measurements might therefore be expected. Especially temperature and global radiation could be affected. The present study analyses parallel measurements at the Groningen Airport to study the possible impact of the solar farm on temperature and radiation measurements. Due to uncertainty about the quality of the parallel measurements for temperature, the results for this variable are validated using the measurements of neighboring KNMI stations. 

We found an increase in the annual mean maximum temperatures of about 0.1 C and a decrease in the minimum temperatures of about 0.1 at the operational location compared to the back-up location. The back-up location is situated about 1.2 km from the solar farm and is not affected by the solar farm. The daily mean temperatures are hardly affected. As expected, the impact on maximum and minimum temperatures is especially visible for directions where the wind blows from the solar farm to the operational location. A comparison with the five nearest inland KNMI stations, confirms the increase in the maximum temperatures at the operational location but also suggest an annual average nighttime cooling of about 0.3 C. The large nighttime cooling is further confirmed by a comparison with all KNMI land stations. This nighttime cooling is thus 0.2 C (annual mean) larger than suggested by the comparison with the parallel measurements at the airport. The reasons for this nighttime cooling are probably related to changes in surface roughness due to the solar farm.

After the installation of the solar farm, KNMI installed a possible new location close to the original location but 35 m further from the solar farm. A comparison between this location and the operational location showed that using this new location would strongly reduce the impact of the solar farm.  

A comparison of global radiation measurements at the operational location and the back-up location does not suggest a significant impact of the solar farm on these measurements. 

It is recommended to relocate the current operational location to the suggested new location. The location is close to the current operational location but at a distance of 65 m from the solar farm. This reduces the impact of the solar farm on (a) the annual mean minimum temperature to a cooling of about 0.1 C and (b) the annual mean maximum to a zero change. It is recommended to monitor this new situation closely in the coming years.