Puerto Rico will link up 7,000 solar systems to help its shaky grid

Sunrun is developing Puerto Rico’s first virtual power plant using rooftop solar and battery systems across the island.

A man wearing a white hard hat and green gloves holds a solar panel
A Sunrun technician installs a rooftop solar panel in Puerto Rico. (Sunrun)
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After Hurricane Fiona struck Puerto Rico on September 18, millions of residents were left without power for days and even weeks as the island’s electricity grid failed once again. Homes and businesses with rooftop solar arrays and battery storage systems, on the other hand, were able to keep their lights on and power crucial medical equipment in the storm’s aftermath.

A new project announced on Tuesday aims to bridge the gap between those who can access the benefits of solar-plus-battery systems and those who can’t do so directly.

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More than 7,000 homes equipped with solar panels and batteries will form the U.S. territory’s first virtual power plant — a sprawling network of systems that are remotely connected and controlled using software and digital communications tools. Sunrun is developing the 17-megawatt system, which is meant to reduce power interruptions and fluctuations on the main electric grid that serves the wider population.

These homes are the building blocks of what can be a resilient, clean, distributed grid,” Chris Rauscher, Sunrun’s senior director of market development and policy, told Canary Media. He spoke by phone from San Juan, where members of Puerto Rico’s solar and energy storage industries are gathering this week for an annual summit.

Puerto Rico Electric Power Authority (PREPA), the state-run utility, selected Sunrun’s proposal for a virtual power plant late last month as part of a slow-moving regulatory process that launched in the wake of 2017’s Hurricane Maria. That deadly disaster all but destroyed the island’s electric grid and left some residents without power for more than a year. 

In response, many of Puerto Rico’s 3.2 million people began searching for their own solutions. Roughly 55,000 rooftop solar arrays with backup battery systems are now installed across the island, with residents and business owners adding thousands more every month as utility customers continue to grapple with persistent power outages, damaging voltage surges and rising electricity bills.

A rooftop solar system
One of Sunrun's rooftop solar installations in Puerto Rico (Sunrun)

Clean-energy advocates have called these solar-plus-battery systems a massive untapped resource” that could help prevent blackouts for everyone.

San Francisco–based Sunrun says it will start enrolling customers — both new and existing — in its virtual power plant (VPP) next year, with plans to start operations in 2024. The network will tap thousands of batteries during high-demand hours in the late afternoon and early evening, nearly every day of the year. The goal is to decrease use of the island’s oil-fired peaker” plants, which are situated near population centers and contribute significant amounts of harmful air pollution.

We are working hand-in-glove with the utility to understand when they need energy most,” Rauscher said, and when we can help defer the need to [run] very expensive, very dirty fossil-fuel peaker power plants — and instead provide some of that energy from our batteries to the grid.” 

For customers, joining the VPP will be a relatively simple process. Sunrun’s solar-plus-battery systems already have the software the company needs to remotely control batteries and network them together. (Sunrun has a dozen other VPP projects in operation or under development across the United States.) Customers will also likely receive financial incentives for joining the Puerto Rico project, though Rauscher said it’s too early to discuss specifics.

Another leading solar developer, Sunnova Energy, said the 17-megawatt VPP is a drop in the bucket” when it comes to Puerto Rico’s virtual power potential. With nearly 40,000 solar customers on the island, Sunnova could provide 1,000 megawatts’ worth of electricity resources over the next 10 years if it were to virtually aggregate those systems, the company said by email.

While the 17-megawatt project is just the start, it also represents a significant milestone in a halting, winding regulatory slog that besets clean energy efforts across the island.

In 2019, two years after Hurricane Maria, Puerto Rico’s government adopted a sweeping energy policy reform to accelerate the adoption of large-scale renewable energy projects and improve the grid’s resilience in the face of extreme weather events. The act requires that 40 percent of the island’s electricity come from renewable sources by 2025 — up from just 5 percent today — and 100 percent by 2050.

As part of that transition, in February 2021, PREPA sought proposals for 150 megawatts’ worth of virtual power plants. (PREPA produces and procures the island’s electricity supply. Luma Energy, a private consortium, operates the transmission and distribution system.) 

Initially, PREPA officials expressed concerns that the VPP technology was too complex or would require significant upgrades to telecommunications networks. They ultimately seemed to settle on a plan to start with smaller pilot projects. 

The 17-megawatt project is the only VPP to come out of that initial solicitation round so far, and Sunrun still has a few final hurdles to clear. The company says it is awaiting regulatory signoff by the Puerto Rico Energy Bureau and the Financial Oversight and Management Board.

This has been a really long time in the making,” Rauscher said, adding that VPPs will be a fundamental piece of the grid going forward.”

Maria Gallucci is a clean energy reporter at Canary Media, where she covers hard-to-decarbonize sectors and efforts to make the energy transition more affordable and equitable.