Hawaiian utilities are using technologies such as the Gridco In-line Power Regulator
(installed below the box located under the distribution transformer) to gain more visibility and control in the face of the impacts of high penetration of PV.
Hawaii continues to be a hotbed of solar activity with rooftop photovoltaic (PV) installation requests nearly doubling every year since 2012. As in California and Arizona, Hawaii utilities are contending with some of the highest distributed generation penetration levels in the U.S., with 17% of their customers having approved or installed PV systems. Renewable momentum and PV adoption are sure to continue as the state strives to meet one of the nation’s most aggressive renewable portfolio standard (RPS) goals: 100% renewable energy by 2045.
At the same time, the electric power industry is undergoing an unprecedented shift as a result of market, political and technological change. Nearly every facet of traditional grid operations is transforming because of increasing levels of renewable generation, especially from behind-the-meter customer generation. Utilities today are in a catch-22 with many business and technical practices based on conventional, centralized fossil generation that are giving way to more customer-sited, distributed resources based on dynamic transactive energy models. While these models lack a long-term track record, the data visibility they provide on performance impacts helps utilities to create new operational confidence and processes.
Faced with fast-paced change on all fronts, and the unique challenges of islanded systems without backup support of interties to other utilities, Hawaii utilities are working with innovative industry partners on pilots with grant support to bridge the knowledge gap. Efforts are underway to deploy new technologies and tools, and to integrate real-time forecasting, advanced decision-based analytics and visualization to better see and manage high levels of distributed weather-dependent renewables. The Hawaiian Electric Companies are demonstrating how collaboration can build practical solutions for proactive change and sustainable transformation toward the next generation of cleaner, more cost-effective renewable generation portfolios while minimizing risks to grid reliability.
State of the Grid
Because of high energy costs and incentives for solar installations in Hawaii, rapid adoption of customer-sited rooftop PV systems swelled rapidly, starting in 2012. With increasing numbers of rooftop PV systems, more circuits on the islands began to experience an excessive drop in the midday load. This resulted in backfeeding when the PV power generated locally exceeded the local need for power. Systemwide, the behind-the-meter solar generation is now as large as, or larger than, any single utility generator, but without the necessary visibility or controls. On Oahu, for example, aggregated behind-the-meter PV is more than 400 MW compared to the single largest utility controllable generator of only 200 MW. As a result, better visibility and the capability to forecast and manage variability impacts of aggregated distributed PV are high priorities.
The Hawaiian Electric Companies operate grids on the islands of Oahu, Hawaii, Maui, Molokai and Lanai. They are already contending with some of the highest levels of renewable generation from both utility-scale and distributed generating resources. Renewable generation of 40% to 50% of system electricity use on some days is among the highest in the nation. This is changing historical customer electrical use characteristics and management of the utility’s central plant dispatch, generation portfolio and reserve planning needs.
Hawaiian grids are exhibiting what has been coined the “Nessie curve,” which is similar to California’s “duck curve.” With the Nessie curve, the daytime load is being reduced by aggregated amounts of uncontrolled midday behind-the-meter PV generation, resulting in a steeper rise to the evening peak as the solar resources go off-line. This steep rise places additional operational burdens on conventional generators not designed to cycle or ramp at such frequency. This Nessie curve is impacting daily system operations on all the islands in Hawaii today. It poses concerns for all islanded grids, which must plan for all generation as well as reserves for operations and contingencies.