You Do Need power plug adapter while traveling from East Timor (Timor-Leste) 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 East Timor (Timor-Leste) are C, E, F and I. This is how they look like.

East Timor (Timor-Leste)

In East Timor (Timor-Leste), outlets of type C, E, F and I are in use.

Type C

Type E

Type F

Type I

Solomon Islands

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

Type G

Type I