content: The reason they're doing this is not to earn money directly. Tesla has already set up completely self sustaining power generation in a number of islands. The setup in that link in particular is sufficient to power a small island (~800 residents and 17 square miles) with nonstop power with just 7 hours of light in any 72 hour period! But those experiments, while successful, always beg the question of whether such ideas can scale upward. Puerto Rico is the answer to that question.