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, according to data provided by the U.S. Energy Information Administration (EIA).
‘The high electricity prices in Hawaii have made wind and solar technologies economically attractive alternatives, especially as their technology costs have come down in recent years,’ notes the EIA. ‘These factors have led to growing wind and solar generation on both the utility scale and in smaller distributed applications"particularly customer-sited rooftop solar PV.’
However, high levels of PV penetration do not come unattended by challenges.
According to the EIA's 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.