Elon Musk: Solar energy is the key to fixing Puerto Rico's power grid

While not an immediate fix, the Tesla CEO says he has the solution.

"The Tesla team has [built solar grids] for many smaller islands around the world, but there is no scalability limit, so it can be done for Puerto Rico too," Musk tweeted Thursday. "Such a decision would be in the hands of the PR govt, PUC, any commercial stakeholders and, most importantly, the people of PR."

Any Tesla solution would be aimed more towards the long-term, rather than the immediate restoration of power that is desperately needed, though.

Only 5.4 percent of citizens on the island have electricity, the Department of Defense said Wednesday.

As of Wednesday, only 14 of Puerto Rico's hospitals had electricity, while 51 were "degraded" and in need of generators for power.

Puerto Rico Gov. Ricardo Rossello said on Monday that it could take one month to restore power to only a quarter of households.

Puerto Rico's electric company said some households may be without power for four to six months.