What are AC block energy storage systems?

Innovations in string inverter technology and software controls are giving rise to AC block energy storage systems. While DC blocks will continue to have their place in the energy storage market, AC blocks provide distinct advantages such as granular control, higher availability and shorter project development timelines.

Why do energy storage systems need a DC block?

AC blocks also provide higher availability, which is defined as the percentage of time an energy storage system is online and operating at its designed capacity. If a DC block’s central inverter fails, a larger section of the energy storage system needs to be shut down to replace it.

What happens if a DC block inverter fails?

If a DC block’s central inverter fails, a larger section of the energy storage system needs to be shut down to replace it. With an AC block, it is relatively simple to swap out malfunctioning components if one string inverter fails, which has the potential to significantly reduce downtime.

How do energy storage enclosures integrate with the grid?

There are two primary configurations for integrating energy storage with the grid. The first is the AC block configuration, where string inverters are internalised in each energy storage enclosure. These inverters convert DC power from the batteries to AC, allowing the energy storage enclosure to directly interface with the grid.

What are inverter-based energy resources?

ble energy resources—wind, solar photovoltaic, and battery energy storage systems (BESS). These resources electrically connect to the grid through an inverter— power electronic devices that convert DC energy into AC energy—and are referred to as inverter-based resources (IBRs). As the generation mix changes, so do the electrical character

When should a DC block be added to an AC inverter?

DC blocks are traditionally preferred at sites where augmentation is required and adding AC inverter capacity is restricted. Augmentation is the process of adding additional capacity to energy storage projects to account for battery degradation, which is caused by several factors such as frequency of use and external temperatures.