Financing Concentrating Solar Power (CSP) projects is highly dependent on plant performance. Yields of CSP plants depend strongly on site-specific meteorological conditions. Meteorological parameters that can influence the performance of CSP plants are Direct Normal Irradiance (DNI), wind, ambient air temperature, and humidity. The sensitivity study shows that DNI is the parameter with highest influence on energy yield of CSP plants. However, the annual sum or average of DNI is often thought as the value giving already a good indicator for Annual Energy Production (AEP) of CSP plants. This thesis is proven wrong, as the study finds that for years with same DNI annual averages AEP could vary as much as ± 9 % due to differences in DNI frequency distribution. Further the beneficial effect of lower latitudes is not expressed in the long-term average of DNI. For parabolic trough plants it is found that with a 10° increase in latitude, decrease in the ratio of AEP to DNI could be around 10 % for the Northern Hemisphere. Due to less favourable irradiance during winter the effect is even stronger for the Southern Hemisphere and is around 14 % per 10° of latitude, which often is counterbalanced by higher DNI annual averages compared to the Northern hemisphere. Keywords: Concentrating Solar Power (CSP), solar resource, Direct Normal Irradiance, DNI frequency distribution, plant performance, influence, latitude-effect, ambient meteorological conditions.