Outback Power Integration Guide

SimpliPhiPower.com

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REV101918

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 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: B

#PV

≥ I

PVChrgMax

/ I

BatChrgMax



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



PV charge controller max = 80A

#PV

≥ 80A/34A = 2.35

So, a properly sized PHI battery bank based on available PV charge would have 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, special care must be taken with

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 for sizing the PHI

battery bank, the minimum number of batteries should be the greater of the two results (Discharge

Calculation & Charge Calculation). In this example, this translates into 5 PHI batteries in the

system.

4.0 – Program Settings for PHI Batteries

In order to maintain the Warranty, it is critical to ensure that the appropriate settings for the desired Warranty

are programmed in all of the system components. This section will cover the basic concepts and settings

for Outback Power equipment.

4.1 – Depth of Discharge

In order to optimize performance and the life of your system and PHI batteries, SimpliPhi Power

recommends programming the equipment settings for 80% Depth of Discharge (DoD). This qualifies for

the SimpliPhi 10-year / 10,000 cycle Warranty on the batteries. Greater DoD is possible but will result in

reduced cycle life. Refer to the PHI 3.5 kWh Battery Warranty to compare DoD settings and the

associated Warranty.