Drive sustainable business development by leveraging the transformative capabilities of the GreenMore+ power conversion system.

July 10, 2025

Peter Lu

Energy Storage Product Manager

In a battery energy storage system, the power conversion system (PCS) is the device that moves energy between the battery and the grid. When the battery charges, the PCS converts grid AC to DC; when it discharges, it converts the battery's DC back to AC and controls voltage, frequency and power quality. Choosing the right PCS matters because its efficiency, voltage range and grid-support functions largely determine how much value the storage system can deliver.

Real-life image of rows of modular energy storage cabinets deployed in an open outdoor space for industrial and commercial use.

Outdoor modular energy storage cabinet

What a PCS actually does

A PCS is a bidirectional converter, not a simple phase converter. It rectifies AC to DC for charging and inverts DC to AC for discharging, while a digital controller regulates active and reactive power in real time. On GreenMore systems the core functions are:

Bidirectional AC/DC conversion. Charge the battery from the grid or solar, and discharge on demand.
Grid and off-grid operation. Grid-tied charge/discharge plus independent inverter mode, with optional seamless transfer and diesel generator support.
Grid support. Independent active and reactive power control, adjustable power factor (0.99 leading to 0.99 lagging) and low harmonic output.
Battery coordination. RS485 and CAN communication with the BMS to follow state of charge and temperature limits.

Real-world image of an agricultural-solar hybrid system combining farmland with elevated and ground-mounted solar photovoltaic arrays.

Farm photovoltaic system

Key specifications to compare

PCS selection starts with the battery voltage and the required output power, then moves to efficiency, protection and environmental ratings. The main parameters are summarized below.

Specification	Why it matters
DC voltage range	Must cover the battery from full charge to cutoff; common ranges are 500–850V and 800–1500V.
Rated power	Sets charge/discharge capability in kW; C&I systems often use 50–250kW and utility systems use MW units.
Efficiency	Higher round-trip efficiency means less energy lost on every cycle.
Topology	A built-in isolation transformer adds galvanic isolation; high-frequency transformerless designs are smaller and slightly more efficient.
Protection rating & temperature	IP20 suits indoor rooms; IP54 and wider temperature ranges suit outdoor sites.

Two common PCS configurations

GreenMore builds PCS units for both indoor equipment rooms and outdoor sites. You can browse the full range on the products page.

	Indoor PCS with transformer	Outdoor MW PCS
Typical power	50–630 kW	1.25–1.725 MW per unit
DC range	500–850 V	800–1500 V
Max efficiency	Up to 97.6%	Up to 98.0%
Protection	IP20, indoor room	IP54, outdoor cabinet
Details	PCS with built-in transformer	1.375–1.725 MW PCS

Sizing and integrating a PCS

The PCS power rating should match both the battery's safe charge and discharge current and the load or grid connection it serves. A unit that is oversized for the battery wastes capital; one that is undersized bottlenecks output. On larger sites, multiple PCS units run in parallel so capacity can be added in stages and a single unit can be serviced without shutting down the whole system.

GreenMore supports communication-protocol adaptation, battery compatibility configuration and system integration, and every PCS carries a 3-year warranty. If you are planning a storage project, share the battery voltage, target power and whether the site is grid-tied, off-grid or a hybrid microgrid, and our team can recommend the appropriate converter. Contact us to discuss the application.

Frequently asked questions

Is a PCS the same as a phase converter?

No. A phase converter changes single-phase or split-phase supply into three-phase power. A PCS is a bidirectional AC/DC converter that connects a battery to the grid, handling both charging and discharging plus grid-support functions.

Does a PCS need an isolation transformer?

Not always. A built-in transformer provides galvanic isolation and robust compatibility in harsh environments, while transformerless high-frequency designs are more compact and can be slightly more efficient. The choice depends on the battery, site and grid-code requirements.

Can PCS units operate off-grid?

GreenMore PCS units support both grid-tied charge/discharge and off-grid inverter operation, with optional seamless transfer and diesel generator integration for microgrid and weak-grid sites.

How is large storage capacity reached?

Multiple MW-scale PCS units are connected in parallel, which allows systems to scale from one megawatt to multi-megawatt installations and to expand in stages as demand grows.