Hawaii's unique island topography divides the state into isolated grids and fosters a heavy dependence on imported fossil fuels to its electric plants. The resulting high cost of electricity has made renewable sources, especially wind and photovoltaic power, attractive alternatives. However, high levels of PV penetration do not come unattended by challenges.
According to U.S. Energy Information Agency's (EIA) monthly net-metering utility data, 9,200 net-metered photovoltaic systems were added in Hawaii in 2014 through October, bringing the total number of customers with net-metered PV to around 48,000.
In Oahu, where most of the state's population resides, roughly 12% of customers have rooftop solar, compared to an estimated U.S. average of 0.5%, the EIA says, citing data from the Solar Electric Power Association. The average capacity of residential net-metered PV systems in Hawaii has also been increasing as larger and more efficient PV systems are installed.
The EIA points out that residential solar PV additions in Hawaii have been slowed by the delays customers experienced in getting approval to interconnect new PV systems to the grid. The delays stem from circuits on the Hawaiian Electric distribution grids reaching levels of rooftop PV capacity that are 120% or more of the circuit's daytime minimum load – a key threshold for Hawaiian Electric's interconnection approval process.
Hawaiian Electric recently entered a cooperative research partnership with the National Renewable Energy Laboratory, the Electric Power Research Institute and SolarCity to study the operational effects of high levels of solar PV on electric grids. Preliminary research results have led Hawaiian Electric to announce plans to clear its backlog of PV applications by April.
The group of utilities also recently proposed a reduction in the rate it pays new net-metered customers in order to reduce demand for rooftop PV and help clear the backlog.
In December 2014, NextEra Energy Inc. announced an agreement to acquire Hawaiian Electric Industries Inc., the owner of three electric utilities. NextEra says it supports Hawaiian Electric's plans to accomplish its PV interconnection goals.