Mitigation options study to allow a large amount of rooftop solar

Identify the hosting capacity where the Smart Home community was planned.

Sacramento Municipal Utility District (SMUD)

A developer had planned a Smart Home community in the SMUD service area. Part of the offering in this community was the inclusion of rooftop solar installations on every home. Of concern to SMUD was how the installation of large amounts of generation in a small area of the distribution system might affect other equipment and other customers nearby. At the same time, SMUD was keen to satisfy the developer and offer options for installation of larger amounts of generation.

DNV worked with SMUD first to identify the hosting capacity in the area where the Smart Home community was planned. The results of the hosting capacity study, using steady-state and quasi-static criteria, were used to identify the capacity of generation that could be installed on each home, on average, without causing issues for other customers or overloading equipment. As significant levels of reverse power flow were envisaged during daytime, the typical distribution circuit analysis was extended to include the secondary circuits up to the individual homes. This allowed the voltage rise beyond the distribution transformer to be calculated and addressed in the study.

A follow-up study was carried out to assess the potential of various mitigation options to allow for higher capacities of solar generation. In this study, several options were investigated including new line regulator technologies, reconfiguration of the secondary system, use of energy storage, and use of smart inverters. The economic impacts of each mitigation measure were also estimated to allow SMUD to make an informed decision.

Value to the Customer
SMUD was able to understand, in detail, the limitations on the circuit at present, and the effects of various mitigation options. These results were used in discussion on options with the developer.