The increase in generation from Non-Programmable Renewable Sources (NPRS) increases the variability and uncertainty of power flows in the network, on the one hand, and reduces the contribution of conventional plants to their regulation on the other. Therefore, the network operator requires more stringent performance in dispatching services, new services and new suppliers for such services. Among the latter there are electrochemical storage systems (SS), which are flexible in management and rapid in response, but still expensive. Here we examine – for a stationary SS pertaining to a given grid supply point in the northern market area – the potential profitability of the simultaneous performance of multiple services and functions (revenue stacking): primary, secondary and tertiary regulation of frequency, trading of energy on the Day-Ahead Market, reduction of imbalances in a photovoltaic system.
Notably, the MUlti-purpose Storage Stochastic sizing Tool (MUSST), a software tool already developed in the GAMS environment, is applied to optimize the size in energy and power and the management of the SS, with the objective function being the expected value of the overall annual profit for the performance of services. Different criteria are considered for choosing the offer prices for tertiary regulation on the Market for the Dispatching Services (here only “step 1” service). In order to take into account the uncertainty of acceptance of the relevant offers, starting from historical data (2019) the probability of acceptance of the quantities offered is estimated, on an hourly basis, for the typical day or typical week of the year. SS with different nominal energy / nominal power ratio are considered: 1 h, 2 h, 4 h and 8 h. As the prices chosen for the tertiary offers do not differ much, the distribution of the power into semi-bands for the services, the overall annual profit and therefore the payback period (PBP) of the investment are quite homogeneous in the various case studies. The expected partial charge-discharge cycles are also evaluated, together with their Depth of Discharge (DoD), and the useful life of the battery, which is longer than PBP in all case studies. Therefore, despite the need to consider other aging factors in addition to DoD, in the first instance cycling aging does not appear critical for the multi-service application which has been analyzed.