A daily pattern of mismatch occurs: every time when a load coincides with a time span of poor PV generation, especially during dusk, dawn, night or when scattered clouds randomly shade the PV modules, the load has to be covered by the grid even if the total PV generation of a particular day could cover the demand. This type of intraday load-generation-mismatch can be overcome by
relatively small energy storage devices since the amount of energy which has to be shifted is always less than the daily energy consumption and the storing period is less than a day.
Further the installation of local storage devices has a positive effect on the stability of the grid, since the highly fluctuating PV generation is smoothed and less energy has to be transported. Additionally local energy storage systems can support voltage and frequency stability of the grid.