A case study presented at the 44th IEEE Photovoltaic Specialty Conference (PVSC-44), held recently, demonstrated how the people in Hawaii can sustain comfortably on 100% renewable energy. The study, carried out by Harumi McClure, Jay Moore, John Borland, Takahiro Tanaka, and Corpuz Poncho, includes on-field data considered for a period of 14 months, commencing June 1, 2016. The investigation included a 7-kWh solar PV system comprising a 5.5-kWh Tabuchi Electric inverter and a 10-kWh Li-ion battery. The peripherals were integrated and attached to the grid in self-supply mode, post-NEM, without supply of excess rooftop solar PV energy back to the utility grid.
How optimization of household appliances support the case
The case study finds that, with optimized time-of-use (TOU) of everyday appliances, the minimization of surplus PV energy dumping and the reduction in grid-buy power from the utility is possible. The first month of solar system usage observed approximately 53% reduction in the monthly bill from Hawaiian Electric (HECO). For the upcoming months, the paper focused on finding ways to achieve zero grid buy. In April 2017, the presenters successfully achieved their desired target.
With close scrutiny of daily electricity usage, and by identifying the stem of spike in energy, the authors managed a zero buy from the grid. Combining solar energy with multiple storage and optimized TOU for key appliances realized these economic beneficial values with the shortest ROI.