PVUSA's Maui host site PV system: A revamping case study

During the fall of 1997, the Photovoltaics for Utility Scale Applications project (PVUSA) and the Hawaiian Electric Company, Inc. (HECO) conducted a cooperative renovation effort on an eight-year old 20 kW photovoltaic (PV) system. This landmark system is located in Kihei, Maul and operated by a HECO subsidiary, Maul Electric Company, Ltd. (MECO). It is owned by the State of Hawaii. PVUSA monitors the system and provides analysis, reporting, and technical support. The system operated well during its first seven years but was forced out of service in November 1996 when several components failed in its obsolete power conditioning unit (PCU). The revamping effort included inspections and diagnostic tests that resulted in several module replacements and repairs and most significantly, three new PCUs to replace the one failed unit. Installing the new PCUs necessitated significant wiring and data acquisition system (DAS) modifications. The system was restarted in December 1997. This paper details system characteristics and performance before and during the first two months after the renovation.