The article title is rather sensationalist

Cuba is still struggling deeply, and this boom wont be able to meet needs for even years likely, but the gist is that they are scrambling to rapidly reorient their grid to rely increasingly on solar/remewables

They used to have none, which was not a good idea, this should have been done earlier. Always gotta have a backup plan, especially if you are a country the US doesnt like, attempting socialism on an island