An estimated 1.5 million Puerto Ricans remain without power more than three months after Hurricane Maria lashed the US territory.

Early this month, the island's energy commission unveiled a handful of proposed regulations that could revamp the island's power grid.

Those proposals emphasize the importance of clean, renewable power from wind and solar — something experts say the rest of the US should embrace, too.

The lights are still out in more than half of Puerto Rico.

After Hurricane Maria struck the US territory on September 20, a crippling blackout descended over its 3.4 million residents, cutting communication between loved ones, spoiling food and life-saving medications, and nixing access to banks and clean water.

The death toll, initially estimated at 64, is now thought to be at least 1,000, according to a recent New York Times analysis.

More than three months after the storm, 1.5 million Puerto Ricans remain without power, and hundreds of thousands have no clean water.

It's the result of an abused electric grid left to rot — and what's happening in Puerto Rico could happen in many other parts of America.

Many mainland states depend on a dilapidated and crumbling network of coal-fired power plants and natural-gas pipelines for electricity, as does Puerto Rico. Many parts of the system are just one big natural disaster — superstorm, flood, wildfire, earthquake — away from being decimated.

"Generally speaking, the US gets about a D+ for things like this," Vivek Shandas, an urban-planning professor at Portland State University, told Business Insider after the fall's triple threat of hurricanes lashed Puerto Rico and mainland US. "Much of our infrastructure was built in the late 1800s and it's beginning to fall apart."

Yet some experts say the storms have offered up a silver-lining for Puerto Rico: the chance to rebuild better, stronger, and cleaner.

Early this month, the Puerto Rico Energy Commission unveiled a handful of proposed regulations designed to help nail down what the future of power will look like on the island.

The biggest takeaway after more than 50 companies and organizations weighed in was that microgrids — mini power networks like wind farms or solar arrays that can often function without direct links to the main grid — will play an important role in the territory's energy future.

Experts say the rest of the US should follow suit.

'This is a time where we could help Puerto Rico take a major level jump'

As in much of the mainland US, the power grid in Puerto Rico is more of a patchwork than a unified network. Most of the island’s large power plants lie on its southern coast, but most of its people live in the north, beyond mountainous terrain that makes distributing power difficult. Power plants owned by Puerto Rico’s bankrupt government-owned power authority, Prepa, are four decades old on average.

A Tesla microgrid on Ta'u Island in American Samoa. Tesla

The week after Hurricane Maria slammed Puerto Rico and unleashed the single largest blackout in US history, Blake Richetta, the senior vice president of a renewable-energy company called Sonnen, boarded a plane bound for the island. Sonnen makes solar batteries designed to supply homes with an independent source of energy, similar to the Powerwall systems built by Tesla.

“We got started as soon as we could,” Richetta told Business Insider. “We knew there was going to be a disastrous situation, and we prepared for the worst.”

To Richetta, providing support was a necessity. But the situation also gave Sonnen the chance to showcase the potential of renewable energy systems as a way to provide immediate power to people in need.

“This is a time where we could help Puerto Rico take a major level jump,” Richetta said. “It’s a humanitarian crisis, but it’s also a huge opportunity for growth.”

Sonnen's batteries capture and store the power made by solar panels when the sun is shining so that it can be used later when it’s cloudy or dark.

Richetta and a handful of Sonnen staff set up half a dozen solar microgrids in communal areas in some of Puerto Rico’s hardest-hit neighborhoods, in partnership with a company called Pura Energia.

In Humacao, a blacked-out province where people were using bacteria-infested streams for washing and laundry, Sonnen and Pura Energia helped set up washing machines powered by the sun. In another part of the island, the companies used the microgrids to set up cellphone-charging stations so that people could attempt to reach out to loved ones on other parts of the island or in the mainland US.

A movement towards a cleaner, cheaper, and more balanced grid

Microgrid systems are already helping provide some coverage to various parts of the mainland US — but most of these projects are still in the early stages.

An AMS project using Tesla batteries in Southern California. Advanced Microgrid Solutions

In Southern California, a company called Advanced Microgrid Solutions is spearheading a project that involves replacing the energy that was once provided by a large (now decommissioned) nuclear power plant with a series of solar arrays and batteries that AMS can turn on and off based on when the prices for conventional energy are low and when there’s the most demand.

“We take hundreds of buildings — picture entire city blocks — and each building has a battery. We get the information from each battery, each building, and operate the whole fleet of buildings like one virtual power plant,” Manal Yamout, a vice president at Advanced Microgrid Solutions, told Business Insider.

The AMS system is still connected to the wider grid, and it isn't designed to provide stand-alone power. But it could.

Islanded microgrids — systems that can run independently of the wider grid — can power entire communities.

Ta’u Island in American Samoa is one example of this. There, Elon Musk's energy company, Tesla, has built a network of 5,328 solar panels and 60 Powerpack batteries that supply the entire island with clean energy. On the Hawaiian island of Kauai, a Tesla solar farm accounts for a fifth of the island's peak energy demand.

The way Yamout sees it, it's less about various individual projects and more about a bigger movement towards a cleaner, cheaper, and more balanced grid. In the event of a natural disaster or emergency, these systems are much more resilient, and perhaps even critical. But if deployed across the entire US, they would also help reduce greenhouse gas emissions, clean up our air, promote energy independence, and make energy distribution more cost-effective and convenient.

"It’s not just about batteries. This is going to take the form of things consumers are adopting anyway — things like the smart thermostats, electric vehicles. It's going to transform the way the grid operates," Yamout said.