LUMA warns power grid is under stress as solar adoption accelerates

LUMA Energy is warning that the rapid expansion of distributed energy resources has pushed portions of the island’s electrical system beyond their physical limits.

By THE STAR STAFF

LUMA Energy is warning that Puerto Rico’s electrical grid is experiencing significant strain as rooftop solar continues to surge, telling regulators that overloaded feeders, voltage instability and rising operational burdens now demand a more rigorous, technically grounded interconnection framework.

The utility delivered the message in a presentation filed under Case No. NEPR‑MI‑2019‑0009 ahead of a stakeholder workshop being held this week by the Puerto Rico Energy Bureau on the revised draft of the island’s interconnection regulation. The remarks by the private operator of the Puerto Rico Electric Power Authority’s electric power transmission and distribution system echoed concerns raised by Energy Czar Josué Colón Ortiz about the impact of rooftop solar oversaturation. Those remarks were rejected by pro-sustainable energy groups such as Casa Pueblo.

According to LUMA, the rapid expansion of distributed energy resources (DERs) has pushed portions of the system beyond their physical limits. The company reports that “121+ substations and 145 circuits now operate above 90% load capacity,” while “105 circuits exceed 100% of daytime design capacity.” More than 25,000 high‑voltage complaints have been reviewed, with more than 21,000 tied to feeders where solar penetration has depressed minimum daytime load and reduced system inertia.

LUMA argued that the proposed new regulation must clearly separate technical interconnection requirements from customer programs such as net metering, community solar or microgrids. The utility cites California, Hawaii and New York as jurisdictions that maintain distinct rules for export compensation and technical screening.

The presentation outlines a “simplified interconnection process” for small, low‑impact systems, paired with supplemental reviews when projects fail initial screens. LUMA stresses that no system should inject or export power without prior written authorization from the operator, and that any modification to an existing installation must trigger a new interconnection agreement.

Cost allocation is another major theme. LUMA said current frameworks fail to account for cumulative upgrade costs from multiple DER installations and do not capture ongoing operational needs, such as voltage regulation, protection coordination, monitoring and re-certification. The utility warns that regulatory lag leaves those expenses uncovered, shifting near-term burdens onto utility operations.

LUMA also raises concerns about meter socket adapters (MSAs), noting that only the utility is authorized to install, inspect or certify metering equipment under Puerto Rico’s electrical regulations. It says that any expansion of MSA use would require additional meter technicians and dedicated funding to avoid ratepayer subsidization.

The filing signals LUMA’s push for a more controlled, technically driven interconnection regime as Puerto Rico’s solar market continues to outpace the grid’s ability to absorb it.