The Hawaii PUC’s recently proposed alternatives to net metering, particularly the “self-supply” tariff, represent a significant change in the rules for solar customers. Similar to a tariff in Queensland, Australia today, this could indicate a new direction nationwide that will place new demands on customer installations.
Given the importance of this for consumers and the solar industry alike, the team at Sunverge has spent the last two weeks examining the details of these proposed tariffs. We’re glad to report that our energy storage systems can meet Hawaii’s rigorous “self-supply” rules today, despite the inherent difficulty in ensuring that homeowners prevent any export to the grid (see the chart above).
To accomplish this, a solar PV and storage system must balance home load, required solar and excess solar in real time, and have the controls in place to automatically “turn off” the PV system when the storage battery is full and home is fully powered. Doing this is complicated by that fact that individual homes vary in terms of the relative size of solar generation to the home load usage.
For example, one home might have an average daily solar generation of 800 W in July and average daily usage of 3000W. A second home might have an average daily solar generation of 2000 W in July and average daily usage of 500W. Under Hawaii’s self-supply rules, the first home will need to import power on a daily basis in July, while the second home will need to turn off its PV system every day to prevent export. So there’s no “one size fits all” option here.
The Sunverge system monitors home load in real-time and directs the inverter, which meets Hawaii’s Transient Over voltage (TrOV2) requirements, to dispatch power to the battery, home or turn off the PV system to prevent export. Sunverge not only allows customers to consume more of their PV, the technology minimizes users’ bills and improves grid stability by creating a more even site load.
Keep an eye out for more details on Sunverge’s Grid-Optimized PV Self-Consumption features.
By James Bickford, Director of Channel Sales at Sunverge Energy
