TECHNICAL FUNDAMENTALS
ConversionGrid-tiedOff-gridGrid-forming
PCS and Inverter Basics for Stationary Storage
The power conversion system is the interface between the battery and the grid — and the part that decides what storage can actually do.
01Introduction
What this article covers
In storage, the terms PCS and inverter are often used interchangeably. The PCS is the bidirectional power stage that moves energy between the DC battery and the AC network — charging, discharging, and managing grid interaction.
02Technical
What the PCS does
On discharge the PCS inverts DC to AC at the required voltage and frequency; on charge it rectifies AC to DC. It also manages protection, synchronization, and — in advanced units — grid-support functions. The PCS rating sets the system's continuous power and response speed.
03Technical
Grid-tied vs off-grid
A grid-tied PCS synchronises to an existing AC bus and can export or import. An off-grid (or islanded) PCS must form the voltage and frequency itself because no utility is present. Hybrid sites need a PCS that can do both and switch seamlessly.
04Technical
Grid-forming capability
Grid-forming PCS establishes and holds stable voltage and frequency, letting sources connect and disconnect dynamically and riding through disturbances. This is what makes a storage-led microgrid technically feasible and resilient.
05Technical
Matching PCS to duty
Choose the PCS for the job: peak-shaving needs high power for short windows; backup needs to hold a load for hours; solar shifting needs to absorb and deliver smoothly. The right topology and rating prevent both bottlenecks and wasted cost.
06Technical
Efficiency and losses
Conversion is not free. Round-trip losses are shared between the PCS and the battery, and they reduce the energy actually delivered. Treat vendor efficiency as a basis for modelling, not a guarantee, and include it in any savings case.
07Related Products
Products referenced
Referenced in this article
Battery Storage Components
PCS and modules for custom or expanded plant.
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Residential Energy Storage
Compact home systems with integrated inverter.
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11FAQ
Frequently Asked Questions
What is the difference between a PCS and an inverter?
In storage the PCS is the bidirectional stage that charges from and discharges to AC, acting as both rectifier and inverter.
Do I need grid-forming?
For grid-tied sites, usually not. For islanded or microgrid sites, grid-forming is what lets the system set voltage and frequency on its own.
How does the PCS affect efficiency?
Conversion losses in the PCS reduce round-trip efficiency, so its rating and topology belong in any energy or savings model.
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