: Hawaii Telecom PV Repower, Maui HI

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Client

Maselli Electric

Industry

Commercial solar / telecom facility rooftop PV

Location

Kahului, Maui, Hawaii

Dates

July 2026 to August 2026

Team Size

Services

Independent engineering review of a 9-sheet PV repower design set - Written comment log and two back-check cycles - Sealed supplemental calculation sheet (AC branch circuits, NEC 705 interconnection) - Hawaii-licensed electrical engineer seal

Summary

A Hawaii electrical contractor asked MHL to review and seal the design set for a rooftop PV repower at a commercial building in Kahului. The new array is 64.31 kW DC and 46.54 kW AC on an existing 277/480V, three-phase, four-wire service. MHL reviewed the set, issued a comment log, back-checked the revision, and sealed the corrected package in about ten days.

Problem / Objective

Maui County requires PV schematics at 30 kW and above to be sealed by a Hawaii-licensed electrical engineer, and out-of-state stamps are not accepted. The contractor needed a seal on a repower that had to stay within Hawaiian Electric’s 1 kW NEM Amendment limit.

Process

Reviewed the issued-for-construction set and sent a Maui jurisdiction brief covering the permit portal, code adoption, and submittal requirements. 2. Confirmed the design basis with the contractor: 277/480V service, a load-side breaker connection at the L1 panel, and NEC 2017 as the stated code edition. 3. Compared the legacy array (152 SunPower 327 W modules, four Fronius 11.4 kW inverters) with the new one (109 Qcells 590 W modules, 109 Enphase microinverters) on an AC basis against the NEM Amendment limit. 4. Established a fault-current basis from the contractor’s field survey plus an assumed 25 kA at the service, and checked the existing 10 kA PV load center against it. 5. Issued a written comment log covering the interconnection breaker rating, disconnect fusing, and a false code-violation warning printed on the calculations sheet. 6. Back-checked the revised set, independently re-derived the branch calculations, and issued the seal with two stated conditions.

Payoff / Results (Metrics)

Sealed set issued about ten days after the request, with no redesign needed. - AC capacity increase of about 0.94 kW against the 1 kW NEM Amendment allowance, documented for the filing. - The review caught a 70 A versus 75 A interconnection breaker mismatch, a fuse size that would not fit the existing 200 A disconnect, and an incorrect branch-current warning on the sealed sheet. - Seal conditions recorded on the set: a required “do not relocate this overcurrent device” label, and replacement of the 25 kAIC PV breaker if verified fault current exceeds 25 kA.

Testimonial

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