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

Here is Why You Need An Adapter

The outlet and plug type used in Cuba are A, B, C and L 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

Cuba

In Cuba, outlets of type A, B, C and L are in use.

Type A

Type B

Type C

Type L