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

Here is Why You Need An Adapter

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

Puerto Rico

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

Type A

Type B

Solomon Islands

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

Type G

Type I