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

Here is Why You Need An Adapter

The outlet and plug type used in Monaco are C, E and F 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

Monaco

In Monaco, outlets of type C, E and F are in use.

Type C

Type E

Type F