This paper presents results of prequalification test for ancillary services of a Battery Energy Storage System (BESS) integrated with a Photovoltaic (PV) plant at the same Point of Connection (POC) installed in Denmark. All services for DK2 area have been tested: Frequency Containment Reserve - Normal (FCR-N), Frequency Containment Reserve - Disturbance (FCR-D), Fast Frequency Reserve (FFR), and automatic/manual Frequency Restoration Reserve (a/m FRR). The study details the rigorous testing procedures and performance evaluations conducted to ensure compliance with the requirements outlined in the "Prequalification of Units and Aggregated Portfolios" document. The prequalification tests include a series of assessments such as step, ramp, and sine response tests, along with Normal Energy Management (NEM) and Alert Energy Management (AEM) strategies. The results demonstrate the BESS's compliance with these requirements, showcasing its ability to provide ancillary services. Furthermore, the study highlights the significant economic profitability of participating in the ancillary service market, emphasizing the substantial financial returns for operator.