Solar irradiance outlook in Eastern Mediterranean 2016

Solar irradiance data is analyzed by in order to roughly estimate the cumulative output of solar power facilities in Israel, considering the strong link between the two variables, as demonstrated in our comprehensive study on PV facilities in Israel. The solar energy cumulative flux, measured at the IMS station in Bet Dagan (Central Coastal Plane) during 2015, was on average 5,269 Wh/m2 per day, which is about 2.8% higher than the 1965-2014 multi-year average, but is well within the standard annual deviation range (±4.0%). Despite, the unusual sandstorms during the second half of 2015, there doesn't seem to be a very significant effect on recorded solar irradiance in Bet Dagan. 2016 is also expected to show above average solar irradiance across Israel.

Bet Dagan is the longest operating IMS (Israel Meteorological Service) station for measuring solar energy flux on ground level, recording solar irradiance data since 1965. The station is thus the most suitable for long-term analysis and in addition is also positioned in Central Israel (more precisely Israel's Central Coastal Plane), one of the regions where solar irradiance was shown to closely correlate with the output of PV facilities and which also fits to serve as the minimum estimate for solar facility performance across Israel, as shown in PEIC 2.0 study.

Figure 1. Solar irradiance measured in Bet Dagan at central Israel in monthly resolution during 2015 (orange) vs. the average for respective months obtained during 1965-2014 (blue). Original data from Israeli Meteorological Service.

The solar energy cumulative flux, measured at the IMS station in Bet Dagan during 2015, was on average 5,269 Wh/m2 per day, which is about 2.8% higher than the 1965-2014 multi-year average, but is well within the standard annual deviation range (±4.0%). It was slightly less than 2014 average solar irradiance of 5,399 Wh/m2 per day, which was in fact record-high since 1970 and third highest since the beginning of measurements in Bet Dagan.

Despite, the unusual sandstorms during the second half of 2015, there doesn't seem to be a very significant effect on recorded solar irradiance in Bet Dagan. However, one should take into account that sandstorms significantly affect solar systems due to accumulation, and thus solar PV systems which are not daily cleaned might have suffered a strong effect during this period - especially the systems with central inverters.

2016 is also expected to show above average solar irradiance across Israel, continuing the trend of above-average irradiance records - similar to the period of late 1960s and early 1970s. Among possible factors to alter this projection is the change in solar activity and a sudden powerful volcanic eruption in the Northern Hemisphere at an intensity of VEI 5.0 or above.