Grid operators and planners adopt distributed energy resources (DERs) to enhance efficiency, stability, reliability, and power quality of the electric grid, in addition, to defer the need for network upgrades. However, in many cases, there is a temporary need for DER supply, such as during peak grid prices and outages. Thus, mobile energy resources can be utilized in these cases to serve several customers at different locations. In this work, we propose a new approach for optimal operation of green mobile energy generation and storage systems (MEGSS). The aim of the proposed approach is to maximize the profit of the MEGSS fleet while meeting customers' requirements. The outcomes of the proposed approach are the day-ahead optimal decisions regarding the customers to be served, the route to be followed by each MEGSS in the fleet, and the onboard resources scheduling. The MEGSS dispatch problem is formulated as a mixed-integer programming (MIP), which is decomposed into two sub-problems: an outer sub-problem and an inner sub-problem. The outer sub-problem decides on the customers to be served and the route to be followed, while the inner sub-problem decides on the onboard resources scheduling. Different case studies are presented to prove the effectiveness of the proposed approach.