Puerto Rico is facing the possibility of months without power after Hurricane Maria slammed into the U.S. territory as a Category 4 storm Wednesday morning.

The storm has passed, but the consequences of a compromised electrical grid, experts say, will be inconvenient at best, and deadly at worst.

Hurricanes like Maria, which barreled into Puerto Rico packing 155-mph winds, generally knock out power when winds tear down power lines and when floodwaters compromise transformers, substations, buried power lines and power plants, often causing a ripple effect throughout the electrical grid.

For the Puerto Rico Electric Power Authority, the islands sole energy service provider, that ripple effect shut off power for 100 percent of its customers. With $9 billion in debt, PREPA may not be able to restore power to the island for up to six months , officials warned.

The day-to-day can unravel in an instant, Julie McNamara, an energy analyst with the Union of Concerned Scientists, told HuffPost on Thursday.