The dairy sector stands out as one of the most energy-intensive segments. In Italy, dairy production is a key pillar of the agri-food economy, but its energy profile is heavily reliant on fossil fuels. To address sustainability challenges and align with EU decarbonization targets, this study proposes a fully renewable energy supply model for a milk and cream processing facility, located in Southern Italy. A bottom-up modeling framework is developed to simulate energy consumption at the component level, integrating mechanistic models based on mass and energy balances, heat transfer principles, and equipment-level performance equations. The simulation is performed using MATLAB, with thermal and electrical demands evaluated across processing stages. The plant processes 300 L/h of raw milk and requires 4,228 kWh/day of energy, of which 82% is thermal. To meet this demand sustainably, a renewable energy system is sized, consisting of a photovoltaic (PV) plant and a battery-based energy storage system (EES). The PV system is dimensioned using high-resolution solar irradiance data (PVGIS-ERA5) for the Cosenza area, achieving a daily generation of 4,740 kWh with an active area of 4,231 m2. The EES, sized at 2,790 kWh, ensures round-the-clock operation. The system supplies both electricity and thermal energy via high-efficiency resistance heaters. The model supports scalable, location-specific energy transition strategies for thermally intensive food industries and contributes to the development of zero-emission, energy-autonomous dairy plants aligned with EU Green Deal objectives.