CUC consultants recommend utility-scale solar, battery projects and RFPs as cheaper alternative to diesel

Saipan — Consultants updating the Commonwealth Utilities Corporation’s Integrated Resource Plan told the CNMI Senate that utility-scale solar paired with battery storage would reduce long-term costs compared with continuing to rely primarily on aging diesel generators, and staff outlined near-term procurement and grid-improvement steps including requests for proposals for independent power providers.

The IRP presentation by Mr. Tenorio, a consultant with GHD, showed that under the firm’s techno-economic modeling large solar-plus-storage portfolios reduced projected net present-value losses versus a “business as usual” diesel scenario for Saipan, Tinian and Rota. Tenorio said, “the net present value, we're looking at, negative 86,000,000 with the solar,” while “business as usual with... diesel generators, we're looking at negative $202,000,000.”

Why it matters: CUC’s electricity rates are driven largely by fuel costs. Committee members were shown historic swings in the fuel-adjustment charge — the presentation noted a low of roughly 8¢ per kilowatt-hour in June 2020, a peak near 43¢ in June 2022, and about 23¢ in February 2025 — and were warned that replacing fuel with lower-cost solar energy and batteries can substantially reduce future exposure to oil-price volatility.

Key findings and near-term steps

GHD’s update recommended large-scale solar PV with battery energy storage as the preferred option for the three islands. The firm modeled specific target capacities to reach a 40% renewable penetration by 2030: Saipan — 60 megawatts (MW) solar and 48 MW battery energy storage (BES); Tinian — 8 MW solar and 3 MW BES; Rota — 3 MW solar and 2 MW BES. Tenorio also…