The solution architecture document explains the design and how it supports the target processes.
In the early stages of idea development and subsequent start of the project the architecture document helps keep record of design decisions and explain how the emerging architecture will support target processes.
As the solution is built incrementally throughout the sprints in the development plan the architecture document is enriched with more details and information about how various aspects of the design address stakeholders’ concerns.
Nearing the end of the development the architecture document provides a valuable asset to operations, maintenance and any future enhancements.
The architecture document is usually considered a mandatory part of the delivery in the formal hand-over of the solution to operations, making the operations team and the future product owners.