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

Here is Why You Need An Adapter

The outlet and plug type used in Niger are C, D, 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

Niger

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

Type C

Type D

Type E

Type F