This study explores the potential of Vehicle-to-Grid (V2G) technology in utilizing Electric Vehicle (EV) batteries for energy storage, aiming to fulfil Spain's 2030 and 2050 energy goals. The validated Simulink model uses 3.15 million EVs in 2030 and 22.7 million EVs in 2050 as primary energy storage. The results show that Spain can achieve its 2030 target of 42 % renewable energy by utilizing 800 GW of PV + Wind, or 220 GW of installations combined with an annual import of 18 TWh. For the 2050 goal of 97 % renewable energy, the study proposes 1300 GW installation without external support, or 600 GW renewable energy source installation with a 50 TWh import. Detailed analysis shows that the storage provided by 3.15 million EVs can replace 122 GW of new energy storage installation in 2030 and 22.7 million EVs replace 2.7 TW of new energy storage requirements in 2050 to support high penetration of intermittent renewable energy installations. The analysis showcases the substantial storage capacity provided by EVs, emphasizing their potential as a primary ESS and the effectiveness of V2G technology in grid support. The overall results underscore V2G technology's role in minimizing the need for additional energy storage infrastructure in the future.