How to Calculate Minimum Battery Sizing
The following table identifies the recommended number of batteries required for inverter-chargers with the shown inverter Peak, Discharge, and Charge values. Using these values with the battery sizing information provided in the HELIOS ESS DC Capacity Values for Sample Battery Systems table in the Minimum Specifications for Battery Systems topic. Identify the recommended number of HELIOS ESS batteries in the last column.
Example Battery Sizing for example inverters
Model | Inverter Peak | Max Continuous Discharge | Max Continuous Charge | HELIOS ESS |
|---|---|---|---|---|
HELIOS ESS Battery | 300 A | 200 A | 200 A | — |
Inverter A | 200 A | 50 ADC | 50 ADC | 1 |
Inverter B | 300 A | 100 ADC | 100 ADC | 1 |
Inverter C | 400 A | 150 ADC | 150 ADC | 2 |
Inverter D | 500 A | 200 ADC | 200 ADC | 2 |
Inverter E | 600 A | 250 ADC | 250 ADC | 2 |
Inverter F | 700 A | 300 ADC | 300 ADC | 3 |
Calculating the recommended number of batteries per inverter
To determine the recommended number of batteries needed for optimal inverter performance, the battery’s peak current, maximum continuous discharge current, and maximum continuous charge current should exceed the corresponding performance values of the inverter.
Inverter A: The HELIOS ESS battery’s peak and discharge and charge currents are greater than the corresponding performance values of the inverter.
One battery is recommended.
Inverter B: The HELIOS ESS battery’s peak and discharge and charge currents are greater than or equal to the corresponding performance values of the inverter.
One battery is recommended.
Inverter C: The HELIOS ESS battery’s peak is less than the inverter, even though the battery’s discharge and charge currents are greater than the corresponding currents of the inverter.
If we use two batteries, the total peak current of the batteries is greater than the peak current of the inverter.
Two batteries are recommended.
Inverter D: The HELIOS ESS battery’s peak is less than the inverter, even though the battery’s discharge and charge currents are equal to the corresponding currents of the inverter.
If we use two batteries, the total peak current of the batteries is greater than the peak current of the inverter.
Two batteries are recommended.
Inverter E: The HELIOS ESS battery’s peak and discharge and charge currents are less than the inverter.
If we use two batteries, the total peak and discharge and charge currents of the batteries are greater than the corresponding performance values of the inverter.
Two batteries are recommended.
Inverter F: The HELIOS ESS battery’s peak and discharge and charge currents are less than the corresponding performance values of the inverter.
If we use two batteries, even though the total discharge and charge current of the batteries is greater than the corresponding currents of the inverter, the total peak current of the batteries is less than the peak current of the inverter.
If we use three batteries, the total peak current of the batteries is greater than the peak current of the inverter.
Three batteries are recommended.
NOTICE |
|---|
EQUIPMENT DAMAGE The internal busbars of the HELIOS ESS are rated to a maximum 400 A.
Failure to follow these instructions may result in equipment damage. |
Calculating Inverter Peak Current
If the inverter manufacturer provides the surge power only, calculate the peak current using the following formula:
Inverter Peak (Amps) = (Inverter Surge Value) / (Inverter Efficiency %) / (48V: Low Battery Cut-Off)
For example, if the inverter’s surge power is 24,000 watts and its CEC efficiency is 95%, the calculation is:
Inverter Peak = 24,000 watts / 0.95 / 48 V
This results in a peak current of approximately 526 A.
To maximize inverter performance, two batteries (with a combined peak current of 600A) are recommended to support the inverter’s peak current of 526 A. If the two batteries can also handle the maximum continuous charge and discharge currents, they can manage the inverter’s charging and discharging needs.