This study explores the integration of diverse flexible assets, including electric vehicles (EVs), stationary battery energy storage (BESS), heat-pumps and photovoltaics, into a localised smart grid to enhance aFRR ancillary service provision and lower overall grid costs. The performance of the grid was evaluated by simulating and analysing various loads, including residential and commercial building heating, EV charging profiles, as well as photovoltaic generation and battery energy storage. This analysis covered six cases across different seasons and years, with each case assessed over a oneday period. Within the grid, three different nodes are analysed; a Residential, Commercial and Mixed node, all with different power consumption and behaviour profiles differentiating between the seasons. The findings demonstrate the potential of EVs to deliver a significant amount of aFRR ancillary power, while still satisfying minimum state of charge requirements set by vehicle owners. Utilising both BESS and EVs in aFRR results in substantial grid cost savings and, in some years, potential profits. However, participation in
aFRR services results in a higher average cost for imported energy (without taking into account aFRR revenue). This rise is attributed to maintaining sufficient capacity for aFRR provision, where the revenue per unit of energy is generally higher. The combination of vehicle-to-grid and BESS-to-grid without aFRR provision showed the lowest cost of imported energy, since here only day-ahead prices are used to optimise load scheduling. In addition, operating a localised grid with regards to imbalance prices can result in 80-160% portfolio savings for balancing responsible parties (BRPs), due to the concept of passive balancing, where the combination of EV and BESS showed to be most promising. The research contributes to the field by providing an insight and potential framework to leverage flexible assets in both commercial and residential smart grid environments, showcasing a significant step toward sustainable energy management, taking into account the perspective of multiple market parties.