Photovoltaic energy storage off-grid inverter

An off-grid solar power inverter, also known as a stand-alone inverter or solar battery inverter, is a device used in an off-grid solar system. It operates independently of the power grid and can't feed electricity to the grid. It has no provision to tap into the grid electricity.

An on-grid solar inverter, also known as a grid-tied inverter, converts the DC power from solar panels into AC power that can be fed back into the electrical grid. With this setup, homeowners can either build credit to reduce their bills for when they need the grid – called net metering – or, depending on where they live, get paid a feed-in-tariff (FIT) for the excess energy they produce.

This white paper presents a hybrid energy storage system designed to enhance power reliability and address future energy demands. It proposes a hybrid inverter suitable for both on-grid and off-grid systems, allowing consumers to choose between Intermediate bus and Multiport architectures while minimizing grid impact.

The multiport structure shown in Fig.4 features a three-port converter and a bidirectional grid inverter. The primary function of the three-port converter is to enable single-stage power conversion, which integrates MPPT for PV systems and manages the charging/discharging of batteries with minimum BOM and improved power conversion efficiency.

The hybrid inverter is configured in two distinct architectures: Intermediate DC Bus Architecture and Multiport Architecture, as shown in Fig. 2 and Fig. 3, respectively. A comparison of the features of each configuration is provided, followed by a detailed description.