Magnum Energy Integration Guide

REV1128

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3.2 – Charge Calculation: Charge Controller Power Sizing

To optimize solar harvesting, a properly sized PHI battery bank should be able to accept the maximum

PV charge current. To determine the minimum number of PHI batteries required to optimize PV, divide

the output of the charge controller(s) by the “max continuous charge current” per PHI battery. Be sure to

verify the “max continuous charge current” for the PHI battery model that you’re using, because it may

differ from C/2 depending on the model.

Charge Example

This example uses the following calculation:

#PV

≥ I

PVChrgMax

/ I

BatChrgMax

This example assumes the following:

• Max. continuous charge current for PHI 3.5 48V = 34A

• PV charge controller max = 100A

The calculation and assumptions correspond to:

#PV

≥ 100A/34A = 2.94

In this example, a properly sized PHI battery bank based on the available PV charge has a

minimum of 3 batteries. This maximizes the use of available PV while ensuring the batteries are never

stressed by overcharging. If the PHI battery bank has fewer batteries than calculated, configure the

inverter settings to limit the charge rate below the specified rating of the PHI battery. These settings are

described in the following sections of this Integration Guide.

In summary: When comparing the same system using these two calculations to size the PHI

battery bank, the minimum number of batteries should be the greater of the Discharge Calculation

& Charge Calculation results.