When you have an active and engaged team of Solvers, your Solverboard will quickly become full of ideas, some aligned to your organisational goals and others maybe not, but are nonetheless valid and potentially viable to take through and graduate into tests, options or projects.
In order to help you manage these effectively, clusters can be created to group ideas into similar themes. Clusters can then be assessed (and graduated) in exactly the same way as an individual idea.
How you choose to cluster ideas is up to you. You may wish to cluster ideas together based on the goal they support, or you may wish to cluster together ideas which have the same key theme e.g. ideas which mention "sustainability".