Guernsey is about 370 times smaller than Solomon Islands.

Solomon Islands is approximately 28,896 sq km, while Guernsey is approximately 78 sq km, making Guernsey 0.27% the size of Solomon Islands. Meanwhile, the population of Solomon Islands is ~702,694 people (635,203 fewer people live in Guernsey).
Tip: This to-scale comparison of Solomon Islands vs. Guernsey uses the Mercator projection, which distorts the size of regions near the poles.