Variabilität der solaren Einstrahlung in 1-Minuten aufgelösten Strahlungszeitserien

Kurzfassung

Due to the greenhouse effect renewable energies become more important and are expanded in many countries. The sun, whose short-wave radiation can be used by different solar energy systems, has the greatest energy potential. Depending on the technology the global horizontal irradiance or the direct normal is used. Short-term variations of the solar irradiance cause fluctuating power generation in the seconds or minute range. Therefore an estimation of the variability at least within one hour is very helpful for plant operators. The statistical analysis of this variability is an important perquisite for the system design, the project development and site selection of the solar system. There already are some variability indices that are based on the global horizontal irradiance. These indices describe the variation of the irradiance within a few seconds, one minute, one hour ore one day. Further indices are used to quantify radiation properties like the frequency of the fluctuation and its height. Every index is calculated in the same way for 1-minute measurements of the global horizontal and direct normal irradiance of the BSRN station Carpentras for one year. Because the variability of the irradiance is primary caused by clouds, hourly irradiance signals are classified visually. The ground measurements of the year 2012 are assigned to these classes by using the hourly resolved variability indices of the direct normal irradiance. These different visual classes can also be derived from cloud structures that originate from satellite images.