You Do Need power plug adapter while traveling from Solomon Islands to Puerto Rico.

Here is Why You Need An Adapter

The outlet and plug type used in Puerto Rico are A and B and in Solomon Islands are G and I. This is how they look like.

Solomon Islands

In Solomon Islands, outlets of type G and I are in use.

Type G

Type I

Puerto Rico

In Puerto Rico, outlets of type A and B are in use.

Type A

Type B