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

Here is Why You Need An Adapter

The outlet and plug type used in Equatorial Guinea are C and E 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

Equatorial Guinea

In Equatorial Guinea, outlets of type C and E are in use.

Type C

Type E