You didn't specify the time frame for the project.
Where will these be installed? West Texas?
This project would normally be broken down into tasks, such as:
1. Design
2. Build
3. Test
4. Install/commission
5. Service
You want an engineering firm/group to do the design/installation drawings and select components and draw them into the plans. You will also want the engineer/s doing the design available to overlook the build/testing and initial installations.
The customer approves the design and selections.
A company is chosen to build out the containers after they have been cleaned, painted, insulated, etc (more contractors, sub contractors).
Someone will need to figure out when and were they will be installed. A crew will need to do the installation following the plans/drawings/documents created during the design process.
A plan will also need to be created in order to service and support.
You will want whoever does the design, to be available throughout the project.
Those Conex containers with the batteries and controls are portable control rooms.
I know of a number of companies that are very good at doing control panels/rooms much more complex than what you show in the pictures.
The guys that do that everyday become very proficient. They are also very good at reporting errors when it comes to the design which is very important.
I'm an engineer, ME/EE, who has run a number of large projects and I have had my own company for 21 years. I could help you out with part of this project, but time frame is everything. I'm usually booked 3-4 months in advance. I am in the Midwest (Indiana) and I try to stay within a state or two of Indiana, but I have done work in Texas twice in the past two years. I usually travel every week.
I have connections to shops throughout the Midwest that can do everything you need. These are not "garage shop" guys. The one fabricator I work with has well over 40,000 sq ft of shop space. They could do all of the Conex container prep, welding in doors, openings, etc. They have a large CNC laser cutter in house and are masters of the craft. A panel shop I work with could easily fit, install, and wire 5 Conex containers at a time inside their shop.
Onsite installation is a different story, but I bet your company knows of a local company who could install these or would your crews do that? That should be relatively easy after everything is tested and proven, and documented.