Colón’s case for tighter rules
Colón argued that the grid has exceeded its physical limits, citing data showing that “more than 80% of the feeders where distributed generation has been developed exceed the 15% penetration limit,” with 35% operating above 70% capacity.
A feeder is the local power line serving a cluster of homes and businesses, and the 15% figure is the threshold regulators use as a rule of thumb for how much solar a single line can absorb before voltage and equipment problems become likely. Colón’s data indicates that threshold has already been broken on most lines with meaningful solar adoption, with more than a third of those lines running above 70% of the total load they were built to carry.
He said the rapid proliferation of rooftop solar in Puerto Rico is contributing to voltage fluctuations, frequency dips, and load-shedding events that disconnect between 130 and 140 megawatts at a time. He also warned that older inverters installed before 2018 are automatically dropping offline during frequency dips, causing an additional sudden loss of roughly 100 megawatts, which he compared to “the equivalent of losing the San Juan 7 unit.”
The Energy Czar said these swings are forcing the Puerto Rico Electric Power Authority’s (PREPA) thermal units to operate at low output levels where they are inefficient and unable to provide adequate frequency control, increasing generation costs and stressing aging equipment.
He urged the Energy Bureau to require full interconnection studies before approving any new solar system, including those under 25 kilowatts that currently qualify for expedited approval.
“No distributed generator should be interconnected until the operator determines that the interconnection is safe,” he said.
Colón also recommended that developers, not ratepayers, bear the full cost of interconnection studies and any grid upgrades needed to accommodate new solar installations. He further asked the Bureau to authorize curtailment of excess solar generation without compensating customers, arguing that compensation would undermine the operator’s ability to manage grid stability.
In addition, he called for mandatory installation and configuration of advanced inverter functions, specifically Volt-VAR and Volt-Watt, for all systems, including those already in operation.
LUMA would gain the final say
Read together, Colón’s requests would give LUMA broad, largely discretionary authority over rooftop solar at both ends of a system’s life. For new installations, no project, regardless of size, could connect to the grid until LUMA completes a study and determines, in the company’s own judgment, that the interconnection is “safe.”
That would replace the automatic, expedited approval process that current law provides for systems of 25 kW or less, and would make LUMA a gatekeeper that can approve, delay, or effectively block a project case by case.
For systems already connected, the curtailment authority Colón is requesting would let LUMA restrict or reduce to zero a system’s ability to export power to the grid whenever it judges that necessary to protect stability, without paying the owner anything for the lost production.
Neither authority exists today. Both are requests Colón has asked PREB to write into the final regulation, and both are what SESA and SUN most directly contest in their motion.
Capacity versus actual output
The megawatt and penetration figures at the center of this debate describe installed, or nameplate, capacity: the maximum a solar system could produce under ideal sun conditions. That is the right measure for the voltage and stability concerns Colón raises, since those problems are driven by a circuit’s peak instantaneous output, not its output averaged over time. But nameplate capacity is not the same as the energy a system actually delivers.
Puerto Rico’s rooftop solar fleet has an average capacity factor of around 18%, according to LUMA’s own regulatory filings and academic estimates of the island’s solar resource, meaning a system rated at 100 MW typically produces output equivalent to roughly 18 MW when averaged over a full year. Dispatchable thermal generation can sustain output much closer to its nameplate rating whenever it is called upon, since, unlike solar, it is not limited to daylight hours.
Puerto Rico’s roughly 1,456 MW of installed rooftop solar capacity amounted to about a fifth of the island’s total generating capacity at the end of 2025, according to federal energy data. But by some independent estimates, rooftop solar has supplied closer to a tenth of the electricity Puerto Ricans actually consume, a considerably smaller share. The 130 to 140 MW disconnection events and the 15% and 70% feeder thresholds Colón cites describe real, instantaneous swings and capacity limits on the circuits where they occur; they are not a measure of how much of the island’s overall electricity supply comes from rooftop solar.
How other grids have handled the same strain
Caribbean Business research shows Colón’s push mirrors steps already taken in some of the world’s most solar-saturated grids. Hawaiian Electric, which serves Oahu, one of the highest rooftop-solar-penetration grids in the U.S., already requires advanced inverters on all new private systems and worked with manufacturer Enphase to remotely reprogram roughly 800,000 existing microinverters, about 60% of Oahu’s distributed solar, to add grid-support functions in a single day, unlocking roughly 140 megawatts of stabilizing capacity. That is close to the fix Colón is asking PREB to mandate for Puerto Rico’s older, pre-2018 inverters.
California’s Rule 21 similarly requires Volt-VAR and Volt-Watt functions on all new distributed generation, and the state’s grid operator has curtailed record volumes of solar output during periods of oversupply. Germany requires new residential systems to either accept remote curtailment or cap output at 70% of rated capacity. South Australia, the world’s highest rooftop-solar-penetration grid, has gone furthest, authorizing its network operator to remotely reduce or shut off residential solar exports during emergencies.
Puerto Rico’s own 15% feeder-penetration screen, the threshold Colón says is already breached on most solar-heavy circuits, is the same benchmark LUMA has separately asked regulators to raise to 30% in prior filings, an indication that the industry, not just the government, sees the current standard as outdated.
Where Colón’s proposal departs from several of these markets is on compensation. Australia and parts of the U.S. mainland have moved toward paying at least partial compensation for curtailed solar output, while Colón is asking PREB to authorize curtailment without paying customers anything at all.
The solar industry’s rebuttal
In a motion to the PREB, SESA and SUN offered a sharply contrasting view, telling regulators that the July 13 draft of the interconnection rule is incomplete and omits several components required by law. Their filing argues that Puerto Rico’s statutes guarantee automatic interconnection and automatic net metering within 30 days for systems of 25 kW or less, upon certification by a licensed electrician or engineer.
“Such systems shall be interconnected automatically,” they wrote, emphasizing that the draft rule improperly replaces this statutory process with multiple layers of utility review and a supplemental study mechanism that could impose costs or restrictions even after a system is installed.
The industry groups warned that the proposed supplemental review process introduces “an unacceptable level of risk” because it can be triggered at any point, potentially after installation or permission to operate, and could result in unexpected upgrade costs or severe export limits.
“A process under which the price, the timeline, or the functions can change after signature, or after commissioning, is simply unworkable,” they wrote.
SESA and SUN also noted that Joint Resolution 5-2026 requires the new regulation to adopt modern interconnection concepts such as proactive hosting capacity planning, meter socket adapters, daytime minimum load, and a customer compensation mechanism for curtailment.
“Of the concepts the Joint Resolution names, only daytime minimum load appears in the July 13 draft at all,” they wrote, adding that the draft omits the required curtailment-compensation mechanism entirely.
The groups urged the PREB to codify the automatic interconnection framework that PREPA and LUMA Energy, the private operator of the utility’s transmission and distribution system, have used for years, arguing that customers and installers need certainty on timelines, costs, and operating terms.
They recommended a registration-based process for systems under 25 kW, a strict 90-day evaluation ceiling for larger systems, a fixed all-inclusive fee for small projects, and a clear methodology for allocating upgrade costs based on proportional benefit. They also supported proactive hosting capacity planning and budgeting as the long-term solution to feeder saturation.
The filings show a widening divide between the government’s push for tighter controls on distributed solar and the industry’s insistence that Puerto Rico’s laws guarantee streamlined interconnection and customer protections.
