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Calcimator

Solar String Calculator

Calculate panels per string from voltage limits and inverter specs.

Inputs

V
V
A
V
V
V
A
%/°C
°F

Results

Max Panels/String

13

Min Panels/String

4

Max Parallel Strings2
Voc at Min Temp40.7 V
Max String Voltage487.5 V
How to Use This Calculator
  1. Enter the panel's open-circuit voltage (Voc) and maximum power voltage (Vmp).
  2. Set the inverter's maximum DC input voltage and MPPT voltage range.
  3. Input the minimum and maximum site temperatures (for voltage derating).
  4. Review the minimum and maximum number of panels per string.
  5. Verify string configuration with the inverter manufacturer before installation.

How the result changes with Panel Vmp

Panel VmpMax Panels/StringMin Panels/String
24147
34145
46104
5683

What each input means

Panel Vmp
Panel voltage at maximum power (Vmp from datasheet).
Panel Voc
Panel open circuit voltage (Voc from datasheet).
Panel Isc
Panel short circuit current (Isc from datasheet).
Inverter Max Vdc
Maximum DC input voltage of the inverter.
MPPT Min Voltage
Minimum MPPT operating voltage of the inverter.
MPPT Max Voltage
Maximum MPPT operating voltage of the inverter.
Inverter Max Idc
Maximum DC input current of the inverter.
Temp Coefficient Voc
Temperature coefficient of Voc (negative value from panel datasheet).
Min Temperature
Minimum expected ambient temperature at your location.

How this is calculated

Worked example, using the default values

  1. Identify Input Parameters
    4 parameters
    Panel Vmp = 37.5, Panel Voc = 45.3, Panel Isc = 11.5, Inverter Max Vdc = 600 = 9 input(s) provided
  2. Calculate Max Panels/String
    Max Panels/String
    13 = 13
  3. Calculate Min Panels/String
    Min Panels/String
    4 = 4
  4. Calculate Max Parallel Strings
    Max Parallel Strings
    2 = 2
  5. Calculate Voc at Min Temp
    Voc at Min Temp
    40.7 = 40.7

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