Home batteries will help bolster Puerto Rico’s grid in emergencies

A new program in Puerto Rico could tap thousands of residential solar-plus-battery systems to help keep the island’s grid from going dark during the height of hurricane season.

Sunrun says it’s planning to launch a first-of-its-kind initiative later this summer that will turn customers with rooftop solar panels and battery backup systems into emergency grid responders. Whenever Puerto Rico’s aging oil- and gas-fired power plants threaten to go offline — due to severe storms, hot weather or basic equipment failures — the residential systems can immediately send power to the grid to prevent rolling blackouts and prolonged outages.

The goal is ​“to keep the lights on for everyone in Puerto Rico,” Chris Rauscher, Sunrun’s senior director of market development and policy, told Canary Media.

More than 75,000 homes and businesses across the U.S. territory have already installed solar-plus-battery projects to avoid the routine outages, damaging voltage surges and soaring electricity prices that plague the centralized system. Since Hurricane Maria razed the island in 2017, work to repair the beleaguered grid has been slow and inconsistent, despite billions of federal recovery dollars.

In response, homegrown clean energy is proliferating. At least 3,000 new systems are added to the island every month, according to Javier Rúa-Jovet, the chief policy officer for the Solar and Energy Storage Association of Puerto Rico, an industry group.

However, many of Puerto Rico’s 3.2 million people still can’t afford to install their own systems or don’t have adequate rooftops, leaving them vulnerable to the whims of the grid. Those residents had to endure multiple outages earlier this month when the heat index reached a record high of 125 degrees Fahrenheit.

“Puerto Rico is on the cusp of blackouts constantly, and at least some part of the island suffers blackouts daily,” Rúa-Jovet said. He added that ​“this approach of tapping residential batteries during power emergencies will help improve grid reliability.”

San Francisco–based Sunrun’s initiative arrives as Puerto Rican energy authorities and companies are pushing to use ​“distributed energy resources” such as rooftop solar and battery systems to address the problems created by decades-old fossil-burning power plants.

Fossil gas and petroleum accounted for 43 percent and 37 percent, respectively, of Puerto Rico’s total electricity generation in fiscal year 2022, according to federal energy data. Coal supplied another 17 percent of electricity. Utility-scale solar, wind and other renewables generated just 3 percent — far below the Puerto Rican government’s goal of using 40 percent renewable electricity by 2025 and 100 percent by 2050.

On June 15, the Puerto Rico Energy Bureau signed off on an ​“emergency demand response” proposal from Luma Energy, the private consortium that operates the island’s transmission and distribution systems. That cleared the way for Sunrun and other companies operating in Puerto Rico, including Sunnova and Tesla, to begin submitting their own plans for participating in the program.

In regulatory filings, Luma dedicated more than $5 million of its total $20 million budget for fiscal year 2024 for battery and emergency demand response programs, which it estimates will help reduce peak electricity demand by 24.6 megawatts. The funds are expected to go toward compensating owners of some 6,000 residential batteries — a relative ​“drop in the bucket” compared to the total number of operating systems in Puerto Rico, but still a promising start, Rúa-Jovet said.

To provide backup power supplies, Sunrun says it will remotely connect and control the systems of participating households using software and digital communications networks. During a power emergency, Sunrun will direct some of the energy that’s stored in the batteries to the grid, while still leaving enough for customers to maintain their normal activities. Rauscher said the concept is different from more traditional ​“demand response” programs that are tied to thermostats, which can automatically turn off air conditioners to reduce stress on the grid.

The program is also separate from Sunrun’s ongoing efforts to develop a 17-megawatt ​“virtual power plant” in Puerto Rico, which is set to launch within two years. The so-called VPP will connect more than 7,000 homes to provide ​“baseload” power to the grid every day at scheduled times. Sunrun has over a dozen similar projects in the works nationwide, including a 30-megawatt initiative with the California utility Pacific Gas & Electric.

By contrast, the new emergency-response initiative in Puerto Rico will draw from batteries only when needed, and it could start as soon as late July — pending final paperwork approvals from the Energy Bureau and Luma Energy.

It’s not yet clear exactly how many megawatt-hours’ worth of emergency power Sunrun’s systems will provide to Puerto Rico’s grid. Sunrun only recently began reaching out to existing customers, though Rauscher said he expects ​“thousands and thousands” of people to enroll. He said participants could earn potentially hundreds of dollars a year for pitching in to benefit the grid.

“We hope this program can evolve and be utilized more frequently” beyond emergencies, Rauscher said. ​“Because every time you dispatch energy from a solar-charged battery in Puerto Rico, that’s a unit of energy that you’re not getting from a fossil-fuel power plant.”