This study examined the potential of renewable energy sources to provide the necessary power for a mobile off-grid automated milking system (AMS) and associated facilities on pasture. This involved choosing the most cost-effective, environmentally friendly, and sustainable power supply for a mobile AMS in Sweden operating May–September and milking 20 cows per day. Weather data, input from the milking system manufacturer (DeLaval), and outputs from two mathematical models, Insight Maker and HOMER, were used to investigate the potential of different renewable energy sources (biodiesel-, ethanol-, or biogas-run generators, solar photovoltaic (PV) panels + batteries) to support the mobile system. Solar-based energy best fulfilled the key requirements of being environmentally friendly, cost-effective, and sustainable. It also gave the lowest net present cost (11,804 USD), levelized cost of energy (0.31 USD), and annual operating costs (178.26 USD) of all renewable energy options considered. Thus use of solar PV panels + batteries is recommended for the mobile AMS facility. Ways of addressing possible challenges that could arise during implementation, uncertainties in input parameters, and limitations in scaling-up and replicating the proposed set-up are discussed.