MidNite Solar Integration Guide

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SimpliPhi Power, Inc. | 420 Bryant Circle | Ojai, CA 93023, USA | [phone] | [e-mail] | SimpliPhiPower.com
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specified rating of the PHI battery. These settings are described in the following sections of this
Integration Guide.
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 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
B
#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 4 PHI batteries in the
system.
3.3 – Midnite Solar Charge Controller Battery Bank Sizing
Examples
The Midnite Solar charge controller’s charge current ratings vary by model. The Midnite Solar Classic and
Classic Lite models are listed below.
• Midnite Solar Classic 150 & 150 Lite 96A
• Midnite Solar Classic 200 & 200 Lite 79A
• Midnite Solar Classic 250 & 250 Lite 62A
Recommended minimum PHI battery bank sizes based on Charge Calculations are calculated in the table
below. The inverter selection and its max load (kW rating) will determine the recommended Discharge
Calculation battery bank sizing, which may increase the recommended minimum PHI battery bank size.
Table 1.0 – PHI Battery Bank Sizing v. Charge Controller Model
Battery
PHI 3.5 kWh
PHI 2.7 kWh
Model Voltage
48V
24V
48V
24V
Max Continuous Charge Current (A) 34 45 26 45
Midnite Solar Model
Max Current (A)
Minimum # Batteries in Bank
Classic 150 & 150 Lite 96 3 3 4 3
Classic 200 & 200 Lite
79
3
2
4
2
Classic 250 & 250 Lite 62 2 2 3 2