A sustainable power supply unit for ISO containers that includes photo voltaic solar panels that produce electric power allowing standardized mounting and attachment on top of ISO containers. The power supply unit can include ISO container corner castings that allow two or more sustainable power supply units to be stacked during transportation and storage. The power supply unit can include a maximum power point tracker, electrical batteries, data handling equipment and an inverter for supplying plug and play electric power to an ISO container or other electricity demanding equipment.