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Puerto Rico’s first community-led microgrid is ready to launch

The Adjuntas microgrid project is a high-profile example of how Puerto Ricans are devising solutions to the island’s fragile and unreliable electricity system.
By Maria Gallucci

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Two technicians install a blue rectangular solar panel on a rooftop with red tiles. A blue cloudy sky is overhead
Solar installers put panels on a rooftop in Adjuntas, Puerto Rico. (Ricardo Arduengo/Honnold Foundation)

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After Hurricane Maria pummeled Puerto Rico in 2017, nearly destroying the island’s electricity system, residents in the mountainside town of Adjuntas devised a novel plan. Small shops near the central plaza would install rooftop solar panels. Rather than keep the clean energy for themselves, the businesses would store it in a communal battery bank, using wires and computer systems to connect the devices as if running their own electric utility.

Now, more than five years later, the Adjuntas microgrid” is nearly ready to launch.

The project has become a high-profile example in Puerto Rico of how residents are devising their own solutions to an electricity system that remains fragile and heavily reliant on imported fossil fuels. Should the island’s main grid go down again — as it did for many months after Hurricane Maria — the shops in Adjuntas will be able to stay open without having to run costly, polluting diesel generators. Neighbors can still buy food and medicine, and they’ll have a place to refrigerate insulin and charge electronics after the next disaster.

In recent weeks, technicians finished installing the 1-megawatt-hour battery storage system, which will tie together 14 businesses and two apartment buildings surrounding the palm-tree-studded plaza. The Adjuntas microgrid is currently undergoing field testing to make sure it can properly draw, store and distribute power from more than 200 kilowatts’ worth of solar panels scattered across the buildings.

This is something that we can feel extremely proud of,” said Arturo Massol Deyá, the executive director of Casa Pueblo, the community organization that’s spearheading the initiative.

On Saturday, Casa Pueblo will lead a march to both commemorate the microgrid’s launch and urge leaders to develop similar projects across the U.S. territory. Joining the parade will be members of the Honnold Foundation, which has invested about $2 million in the microgrid, and the engineers who worked on the project, including some from the University of Puerto Rico’s Mayagüez campus and Oak Ridge National Laboratory in Tennessee.

We want to celebrate our achievement in a way that advocates for energy security for everyone in Puerto Rico, not just in Adjuntas,” Massol Deyá told Canary Media. Energy should be in the hands of the people and of the community itself.”

Adjuntas is a tranquil town in Puerto Rico’s mountains. (Isabela Zawistowska/Honnold Foundation)

The microgrid is part of a larger effort to ensure that more of the island’s 3.2 million people can access the benefits of resilient renewable-energy projects — particularly given the ongoing struggles of the centralized system.

Despite billions of dollars in federal disaster relief after Hurricane Maria and years of repair work, Puerto Rico’s grid continues to experience frequent outages and damaging voltage surges. The government’s decision to put private companies in charge of operating the island’s transmission and distribution system and, most recently, its power plants has done seemingly little to improve operations or curb rising electricity costs.

In response, Puerto Ricans have installed at least 55,000 rooftop solar arrays with backup batteries on homes, stores, hospitals and fire stations. The technology has proved to be a lifeline. Last September, after Hurricane Fiona struck Puerto Rico, every utility customer initially lost power. But those with solar panels and batteries were able to run crucial medical devices and operate communications networks in the storm’s aftermath.

Still, many Puerto Ricans can’t afford to install their own systems, or they can’t accommodate the extra equipment on their homes and shops.

One way to bridge the gap between the solar haves and have-nots is to develop virtual power plants,” which remotely connect many disparate installations. Sunrun has begun developing the island’s first VPP: a 17-megawatt system composed of 7,000 solar-plus-battery units. The goal is to inject clean electricity into the main grid to help reduce power interruptions and fluctuations, improving service for the wider population.

Community microgrids offer another solution. Solar panels and batteries are distributed among buildings and interconnected using software programs and electronic controls. Together, the units can hook up to the main grid, supplying electricity or drawing on utility power when everything is working well. Crucially, the microgrid can detach and operate independently when disruptions occur. Along with Adjuntas, the communities of Maricao, Cailes and Castañer also have or are building microgrids.

Overcoming setbacks and skepticism for a first-of-its-kind microgrid 

Adjuntas sits high up in Puerto Rico’s central mountain range, with steep, narrow streets leading to the central plaza. Its remote location and challenging terrain have meant the town is often one of the last places to be reconnected to the central electricity system following a disaster. After Hurricane Fiona brought historic flooding and caused dangerous landslides, some homes in Adjuntas didn’t regain power for a month.

The new microgrid is an attempt to address some of the challenges that such isolation brings by insulating at least part of the town from future blackouts.

It’s been a whirlwind,” Cynthia Arellano, a project manager for the Honnold Foundation, said of the Adjuntas initiative.

A worker installs solar panels on the roof of Lucy’s Pizza in Adjuntas, Puerto Rico. (Ricardo Arduengo/Honnold Foundation)

Since 2019, when the project officially began, participants have navigated a series of setbacks. A spate of earthquakes in January 2020 caused significant damage in the region. Not long after, the Covid-19 pandemic upended daily life and disrupted global supply chains. The resulting shortage of semiconductor chips from China delayed the installation of the Adjuntas battery storage system by nearly half a year.

At the same time, the microgrid’s earliest proponents had to convince skeptical or uninterested local business owners that joining a first-of-a-kind initiative would be worth their while.

Ultimately, 16 participants formed the Community Solar Energy Association of Adjuntas, or ACESA, to manage the microgrid. Its members include a pizzeria, bakery, pharmacy, hardware store and a church. Everyone pays a fixed monthly rate for the solar electricity they consume. The group uses that money to cover the costs of operating and maintaining the system. Notably, the fees will also help lower-income families and rural shops to install their own solar panels and batteries.

To start, ACESA members will pay 25 cents per kilowatt-hour of electricity, said Ángel Gustavo Irizarry, the group’s president. The rate is less than the 27.53 cents/​kWh that commercial utility customers paid in December 2022, according to the latest figures from the U.S. Energy Information Administration. However, microgrid participants won’t have to worry about surprising surcharges whenever the costs of importing oil and gas for power plants skyrocket.

Completing this project will be a blessing for business owners, for our staff and for the community that we serve,” said Irizarry, who also owns Lucy’s Pizza, a bustling restaurant on a corner of the main square.

An overhead view shows a pink building with rooftop solar panels. Green mountains rise in the background
A senior-living facility in Adjuntas, Puerto Rico has rooftop solar panels and a backup Tesla Powerwall battery. (Fabio Andrade/UPRM)

The community ownership model isn’t the only unique aspect of the project. The 1-megawatt-hour microgrid also includes novel technology that can digitally connect the solar panels and batteries.

Experts at Oak Ridge National Laboratory are developing an orchestrator” tool that’s meant to keep the system running smoothly during an extended grid outage. Technically, the Adjuntas project involves two smaller microgrids, with batteries divided among two storage containers on opposite sides of the plaza. The orchestrator tool will enable the separate systems to work in concert by sharing information and giving or taking each other’s electricity supply as needed.

If there’s damage to one or even both microgrids, they’d be able to operate at least in some capacity and still be able to provide backup power,” said Ben Ollis, an Oak Ridge engineer who is leading the project with his colleague Max Ferrari.

Larger-scale energy projects on the U.S. mainland use similar tools — called distributed energy resource management systems — to control and coordinate solar arrays, batteries and backup fossil generators across the broader grid. Ollis said his lab’s orchestrator is the first that’s designed to operate at a much smaller, localized level.

This is going to be our proof of concept,” he said. We’re trying to design it in such a way that it can be expandable to any number of microgrids” in Adjuntas and beyond.

The Oak Ridge team received a $3.8 million grant from the U.S. Department of Energy for the orchestrator tool, which they’ll continue developing until the grant expires next year. Arellano of the Honnold Foundation said her organization will also remain involved in Adjuntas to help maintain and evaluate the installation.

Once the microgrid is up and running, the community will be more prepared to face future disasters, said Massol Deyá of Casa Pueblo. I’m not going to say we’re safe from climate change,” he added. But we’re going to be in a much better position during the next hurricane season.”

Maria Gallucci is a senior reporter at Canary Media. She covers emerging clean energy technologies and efforts to electrify transportation and decarbonize heavy industry.