Over-voltage disconnection of DER inverters: Assessing customer savings

Distributed energy resource (DER) owners experience a loss in economic benefits due to prolonged and/or frequent inverter disconnection. In this paper, we investigate the economic savings that customers accrue when combining rooftop solar photovoltaic (PV) generation with battery storage systems, considering a time-of-use pricing tariff and the steady-state over-voltage disconnection of inverters. In particular, we compare four quadratic program (QP) optimization-based approaches to designing the charge and discharge schedule of residential batteries. The objective of the first optimization-based approach is to increase the economic savings that PV customers with battery storage accrue. The next two approaches additionally modulate the power to and from the grid, reducing the occurrence of inverter-based disconnection for improved economic savings. By contrast, the fourth approach directly manages customer-based power flows to and from the electric grid to smooth distribution load curve peaks and valleys, without explicitly considering energy savings that accrue to customers. By means of a case study, we observe the over-voltage disconnection of residential-scale inverters decreases with the proliferation of behind-the-meter batteries until an integration level of 60% is reached. At battery integration levels beyond 60%, the fourth grid-focused optimization-based approach continues to improve the grid voltage preventing inverter-based disconnections.