Solar power generation intermittency and aggregation

Abstract

The inherent intermittency of solar power due to diurnal and seasonal cycles has usually resulted in the need for alternative generation sources thereby increasing system operation costs. However, when solar power is spread over a large geographical area with significant time differences, the intermittency can be significantly reduced and also the electricity market balancing cost. The aim of this article is to address the fundamental scientific question on how the intermittency of solar power generation is affected by aggregation, which is of great interest in the wider power and energy community and would have profound impacts on the solar energy integration into the energy supply and Net-Zero Implementation. This article goes beyond the typical regional analysis by investigating solar power intermittency at 5 aggregation levels from a global perspective based on global 7 year hourly meteorological re-analysis data with a fine spatial resolution of ${0.25}^{\circ }\times {0.25}^{\circ }(\sim 28\mathrm{km}\times 28\mathrm{km})$. In the proposed assessment framework, a coefficient of variation (CV) is used to quantify solar power intermittency and hence characterize the potential benefits of wide area solar power aggregation. A duration curve is used to characterize the intermittency in terms of power availability and a probability density function is further employed to investigate the dispersion and scaling behavior of CV at different aggregation levels. The findings indicate that the CV of solar power generation of ‘Inner Mongolia’ in China drops from 129.65 to 105.65% in the level of ‘Asia’ (by 24% decrease), to 56.11% in ‘Asia-North_America’ (by 73.54% decrease) and to the smallest 43.50% in ‘Global’ (by 86.15% decrease), nearly 3.5 times of that in ‘Asia’; (b) the availability of solar power generation increases from 52.17% in Germany, to 73.30% in ‘Europe_EU_plus’, to 77.82% in ‘Europe’, to 98.59% in ‘Europe-North_America’ (80.60% in ‘Europe-Africa’, 96.90% in ‘Europe-Asia’), to 100% in ‘Global’. Finally, conclusions and recommendations are provided to support a Net-Zero strategy.