Design of a low voltage DC grid interfacing PV and energy storage systems

A design of a Photovoltaic (PV) power system architecture with energy storage system for low voltage DC grid applications is presented in this paper. The system components include the following: PV panels with non-isolated dc-dc interleaved boost converters, batteries with non-isolated bidirectional buck converters. The PV converter is controlled using perturb & observe for maximum power point tracking. The batteries' converter is controlled to regulate the DC bus voltage. These parts are linked together with the utility grid through a 600V DC bus. An energy management system is used to control the power flow between the system components. As an example for the low voltage DC grid system integration; a total number of 1,008 panels can be installed on the rooftop of a selected building, with a total power of 320kWp. Different scenarios are considered for the connections of both PV and batteries. A scaled-down experimental prototype, for the PV system with an energy storage system, is used to validate the presented concept.