Inverter Selection vs. battery system


WSTECH offers different central inverter series:

APS Outdoor series

  • Power from 600kVA to 5000kVA
  • Several worldwide certificates available

BAT Outdoor series

  • 100kVA and 280kVA
  • IEC or UL certified version

BAT / BATI Indoor series

  • 50 – 900kVA
  • IEC certified version


Step 1:

For the correct inverter selection, the battery system must fit to the specified DC voltage range of the inverter series. (Please refer to the Data sheets – DC voltage). It is important to consider the DC-min-value at 10% grid overvoltage.

Example: The voltage range of the selected battery system is 750VDC – 1100VDC. The requested power is 1500 kVA. In this example the APS1600-ES-2-440-5 the range of 713VDC min. (@10% grid side overvoltage) to maximum 1500Vdc max. fits perfect.

Step 2:

Selection of Inverter Power

The AC-Voltage has been selected in step 1, always 4 power classes are available per grid voltage.

Example with 440Vac:

APS800-ES-1-440-5, APS1600-ES-2-440-5, APS2400-ES-3-440-5, APS3200-ES-4-440-5

For pure grid tied Energy storage systems, the inverter Power can be selected easily considering the requested Power Factor based on our data sheet´s value of apparent Power.

For island grid / off grid application the selection of required inverter power is more complicated. Detailed information’s for the correct inverter selection can be found in the document “Inverter selection for Island grid application”

Step 3:

Selection based on Application

The max. short circuit contribution of the connected battery system and the resulting maximum number of battery racks that can be connected at the inverter must be considered

For long duration Energy storage systems, the option DC separation (APS Series only) enables to connect more battery racks with up to 4 times 140kA to be connected to one APS-unit. The DC separation has an integrated common mode filter. The DC separation option gives the opportunity to connect different battery types to one inverter, up to 4 independent controllable inputs are possible.

For island grid / black start applications it is important that you refer to our document: “Application Note – Inverter selection in island grids”.

Step 4:

Selection based on Ambient conditions, to be considered:

  • Altitude of the plant
  • Minimum ambient temperature
  • Maximum ambient temperature
  • Salty environment requiring C5M protection
  • Seismic Area

Step 5:

Selection based on needed certification

The WSTECH APS Series have passed a lot of certifications worldwide, let us know which specific grid code must be fulfilled in the project

Want to learn more? Please refer also to the technical documents in section Media.