You Do Need power plug adapter while traveling from Congo 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 Congo are C, D and E. This is how they look like.

Congo

In Congo, outlets of type C, D and E are in use.

Type C

Type D

Type E

Solomon Islands

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

Type G

Type I