Solar panels began filling a parking lot outside a children’s hospital this week as Elon Musk’s first major solar-plus-storage project in Puerto Rico took shape, demonstrating how quickly solar microgrids can be established for long-term clean, resilient power.

It’s one small but telling step in a U.S. territory of 3.4 million people still largely in the dark five weeks after Hurricane Maria struck.

Musk, the chief executive of Tesla and SolarCity, launched a conversation about bringing solar microgrids to the island a little over two weeks ago in a Twitter exchange with Puerto Rico Gov. Ricardo Rossello. Musk suggested that pairing solar panels with battery systems had worked for other islands and could help Puerto Rico rebuild from the hurricane, too. Rossello’s quick response: Let’s talk.

“Hospital del Niño is the first of many solar+storage projects going live,” the tech company tweeted with photos on Tuesday. CBS correspondent David Begnaud, who is in Puerto Rico, reported that the installation would generate enough energy to power the hospital during the day and store 500 kilowatt-hours of energy for power at night.

Tesla has declined to provide details about its plans in Puerto Rico, saying only to watch for updates through its Twitter channels.

While Musk has been drawing most of the attention for the solar microgrid push in Puerto Rico so far, his is just one of several efforts to bring power back to an island where some three-quarters of the population still lacks electricity.

Sonnen, a German-based battery company, said it was shipping solar-plus-storage systems to Puerto Rico to support disaster response efforts and planned to work with partners on developing microgrids there. Sunrun and other solar providers have been working together to send solar power supplies to the islands. Non-profit groups, too, have brought in installers and donated materials to help communities power up.

Restoring power to all of Puerto Rico could take at least six months to a year―more than 2,000 miles of above-ground transmission lines are knocked out, and the U.S. Department of Defense reports that 62,000 utility poles are needed. Concerns are already rising about how the government-owned utility, which was bankrupt before the hurricane devastated its infrastructure, plans to make that happen.

The utility drew questions from members of Congress this week when the Washington Post reported that it had hired a small private company based in Interior Secretary Ryan Zinke’s hometown of Whitefish, Montana, to rebuild its power infrastructure, rather than accepting mutual aid offers from other utilities.

How Microgrids Could Power the Island

Before the hurricane, Puerto Rico was already in need of grid modernization “as much or more than any place in the continental U.S.,” said George Crabtree, director of the Joint Center for Energy Storage Research.

On average, power plants on the island are about 44 years old, and most are run by the main utility company, Puerto Rico Electric Power Authority (PREPA), which filed for bankruptcy this year and is $9 billion in debt.

Because Puerto Rico has to start from scratch, it has an opportunity to solve many of its long-term energy problems and shift to a cleaner energy source that is dropping in price, said Cathy Kunkel, of the Institute for Energy Economics and Financial Analysis.

“Microgrids are pretty key to build in sustainable way that’s more resilient going forward,” she said.

The cost of renewables is comparable to the prices customers already paid for electricity, and a new, decentralized grid would be more conducive to integrating distributed energy, Kunkel said. That could help raise the island’s renewable energy portfolio, which is currently only at 2 percent, and make it more resilient to future storms.

The interest from private companies is already there. Solar companies like Sonnen and Sunrun are partnering with local nonprofits to provide battery and solar supplies. Tesla has been among the most ambitious with its efforts: in late September, Bloomberg reported the company was shipping hundreds of Powerwalls―its home batteries that can store energy from rooftop solar―to the island. Musk has been in talks with Gov. Ricardo Rossello to scale up the effort by sending Powerpacks―giant battery packages equal to 16 Powerwall batteries―to bring hospitals and city centers back online.

That battery technology “could be used effectively to restore electricity to rural and isolated communities first, where they could provide electricity well ahead of when grid rebuilding efforts are likely to reach those communities,” said Clark Miller, associate director of the School for the Future of Innovation in Society at Arizona State University, which partners with the University of Puerto Rico’s National Institute of Energy and Sustainability.

The new microgrids could work in tandem with the fossil fuel-powered centralized electricity grid, particularly in future storms like Maria, energy experts say.

“These can provide individual pockets of power that would be hugely supportive to emergency relief and communications, to light and power tools for rebuilding, for the cleaning and distribution of water next time,” said Roy Torbert, principal on the Islands Energy Program at the Rocky Mountain Institute.

Setting Up for Long-Term Energy Success  

A major question is who will pay for the grid updates, and how the utility could manage long-term contracts with solar or battery companies. “There’s a limit to what philanthropy can provide,” Torbert said. Regulated utilities can only pass costs on to customers to the extent allowed by law.

Puerto Rico Secretary of Economic Development and Commerce Manuel Laboy, who has been involved in talks with Tesla, told Bloomberg that the territory is serious about transforming its energy infrastructure and is considering microgrids with solar and other renewable sources but that funding is a concern.

“There’s a long way to go,” Kunkel said. “From a technical standpoint, there no reason you couldn’t integrate solar and battery backup, but there has to be a commitment on the part of the Puerto Rican government that that’s the direction and they want to see investment in these areas.”

Building out microgrids in rural and urban areas could help jump-start a new economy for Puerto Rico, adding installer and maintenance jobs at renewable energy and storage companies.

“The goal is to teach people to be literate with solar technology to the point where they won’t depend on grid or on power bills in the future,” said Walter Meyer, co-founder of Resilient Power Puerto Rico. “They can invest in their own businesses or jobs, or hire new employees, which helps grow the Puerto Rican economy from the ground up.”  

Meyer and a team of volunteer solar installers have been working in rural Puerto Rico, bringing renewable, off-grid power to homes that will likely be among the last to see their grid power restored, and teaching people about solar technology as they go. Solar companies have donated panels, solar generators and inverters to the group’s efforts, and battery manufacturers have provided batteries or sold them at less than wholesale prices, Meyer said.

“It’s an all-in effort,” he said. While the government focuses on restoration efforts in populated areas of the island, “we’re working from edge of grid in and expecting to meet in the middle at some point.”

The ultimate goal is to create a system of microgrids―small-scale power grids that operate independently of the centralized grid―that can utilize renewable energy like rooftop solar.

“You’re never going to see Puerto Rico the same again from a technology perspective,” Meyer said. “Every level of government is talking about microgrids.”