A little off topic, but it may be a better solution. A Storedge/10 kWh LG battery combination will give you free electricity all summer long and backup power when the grid is down. No more worrying about your island dock circulator when the ice is too dangerous for the Co-op to get out and restore power, no fuel required, and no maintenance costs. Yo do of course need a good southern exposure and are limited to about 30 amps of essential loads. Starting cost for a simple roof mounted on island system would be just over $26K gross, and around $18K net after the 30% tax credit.
Here is a link for a great short video on how the system works;
https://www.youtube.com/watch?v=L6wglt9oCEA