The Cuban government has refused a request by the U.S. Embassy in Havana to allow it to import diesel for its generators while the Trump administration continues to impose a fuel blockade on the island, according to two U.S. officials familiar with the matter.
It doesn’t really matter if they’re for emergencies or they’re the main power source. Since the Cuban grid is down, the US embassy could only get power using those generators. So, now they’re as in the dark as the rest of Cuba.
While the Cuban government could still communicate with messengers on motorbikes, the US can hardly do that to communicate with the US mainland, so they’re going to be really cut off.
I assume they have some kind of satellite phone and some spare batteries, but unless they have solar panels or something, once those batteries are gone they’re really cut off.