The savings are not immediate as you know, the grid is from your house to your neighbors using buried cables (less damage during hurricanes).
As the North Island grows your energy production grid grows as well. Using the same calculations that you did when you built your system per house or commercial property. Here is the benefit, the houses that are vacation homes still connect into the grid and continuously produce for the grid. Battery backup systems can be connected as well so as to provide power during the night.
In the future fuel and energy cost will increase (energy cost in the US is projected to double in five years) this will raise your .22/Kw to .44/Kw. Solar panals can produce 300w at this time, in five years they are projected to produce 1kw/ panel. The cost of a solar/ wind power system is not the equipment but the install. The money that a community pools together to install renewable systems will significantly benefit the community in the next 5-10 years.
I am still learning more about these systems as is anyone in this business, which I am not. I have not looked into the laws of Belize in regards to coops, but will do so during my next visit.
I believe that it can be done but would require a group of interested parties to sit down and discuss appropriate courses of action.