SimpliPhi Battery Manual

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(Load Rate)÷(MAX Continuous Discharge Rate per Battery)
=Minimum Battery quantity to prevent overdischarge
Example, continued: Three PHI 3.8 kWh batteries must be paired with an inverter rated at 5 kW AC and 92% efciency to
ensure the PHI Battery bank does not over-discharge to power the loads.
(5.4 kW DC)÷(1.92 kW DC)=2.83 --> round to 3
Refer to the Battery Bank Sizing for Maximum Instantaneous Discharge (Load Rate) tables in Appendix B of this Manual for
a complete list of common battery-based inverters and the minimum quantity of PHI Batteries those inverters need to be
paired with to ensure that the PHI Battery bank does not over-discharge. Over-discharging the PHI Batteries will destroy
them and Void the Warranty.
In the case where the inverter’s AC Power Output rating exceeds the connected loads’ actual power draw (i.e. the inverter is
rated at 5 kW but all loads amount to 3 kW of maximum instantaneous power draw), SimpliPhi still expects that the proper
additional precautions be made to ensure that the PHI Battery bank is not over-discharged. Failure to do so will destroy
the PHI batteries.
3.2.2 – Sizing for Maximum Instantaneous Charge Rate (DC Coupled)
In a DC Coupled system, the solar PV array output can be mitigated using charge controllers. However, reducing the solar
array’s power output using charge controller programming implies that the PV array’s output is also reduced for the entire
remainder of the system, including the solar power available for powering loads and for exporting to the grid. Furthermore,
greatly reducing the PV array’s output via the charge controllers effectively wastes the solar PV array’s power and puts
strain on the charge controllers.
Calculate the minimum quantity of PHI Batteries needed to prevent over-charge from the solar PV array by considering
both the solar array size and the charge controller’s potential output. Whichever value is less should be used to size the
PHI Battery Bank. If the solar array’s maximum potential current output is less than the paired charge controller’s Output
Amps rating, then the solar array’s maximum potential current output can be used to size the PHI Battery bank. If the charge
controller’s Amp rating is less than the solar array’s maximum potential current output, then the charge controller’s rating is
used to size the PHI Battery bank.
Divide the system’s potential charging current by the MAX Continuous Charge Rate per PHI Battery (found in Table 1.0 or
on the relevant battery’s specication sheet) to calculate the minimum quantity of PHI Batteries needed to ensure that the
solar PV array does not over-charge the battery bank.
Example: Three PHI 3.8 kWh-51.2V
nominal
batteries (used in a 48-Volt system) must be paired with a 4,500-Watt solar PV
array wired to an 80 Amp-rated charge controller. In this case, the 80-Amp charge controller is used to determine the
minimum PHI Battery quantity needed to prevent over-charging from the solar PV.
Watts = Amps × Volts
4,500 Watt Solar PV Array = Amps × 48 Volts
= 93.75 Amps = MAX potential solar PV array output
80 Amps < 93.75 Amps --> 80 Amps
= MAX potential solar PV array output through the charge controller
(MAX potential charging current) ÷ (MAX Charge Rate per Battery)
= Minimum Battery quantity to prevent overcharge
(80A) ÷ (37.5A) = 2.13 --> round to 3
(4,500 Watts)
(48 Volts)