Morningstar String Calculator

Module Info

Select a Manufacturer & Model

Manually Input Module Specifications

Manufacturer Model

Pmax W

Maximum Rated Power (watts)

This is a required value

The maximum rated power at STC.
This is the rated power output of the solar module.
NOCT °C

Nominal Operating Cell Temperature

This is a required value

The NOCT is indicative of the thermal design of the module
and is important for module output calculations. The NOCT
value can be found in the module technical datasheet.

Voc
V

Open Circuit Voltage (volts)

This is a required value

This value can be found on the rating label on the back of
the module or on the technical data sheet provided by the
manufacturer. Voc is the unloaded output voltage of the module.

Voc Coefficient V/°C

Open Circuit Voltage
Temperature Coefficient (volts/°C)

This is not a required value.
Specify a value, if provide, for optimal results.

This value specifies how much the module Voc changes
with temperature. Units are usually specified in
millivolts per degree C or % of Voc per degree C.

Vmp V

Maximum(Peak) Power Voltage (volts)

This is a required value

Maximum, or Peak, Power Voltage is the module output voltage
where maximum power is produced under STC conditions.
This value can be found on the rating label on the back of
the module or on the technical data sheet provided by the
manufacturer.

Sometimes listed as Vpp on datasheets.
Vmp Coefficient V/°C

Maximum(Peak) Power Voltage
Temperature Coefficient (volts/°C)

This is a not a required value.
Specify a value, if provide, for optimal results.

This value specifies how much the module Vmp changes
with temperature. Units are usually specified in
millivolts per degree C or % of Vmp per degree C.

Isc A

Short Circuit Current (amps)

This is a required value

The current produced by the module @ Standard Test Conditions(STC)
when output voltage = 0 Volts. This value can be found on the rating
label on the back of the module or on the technical data sheet
provided by the manufacturer.
Isc Coefficient A/°C

Short Circuit Current
Temperature Coefficient

This is a not a required value.
Specify a value, if provide, for optimal results.

This value specifies how much the module Isc changes
with temperature. Units are usually specified in
milliamps per degree C or % of Isc per degree C.

Imp A

Maximum (Peak) Power Current (amps)

This is a required value

Maximum, or Peak, Power Current is the module output current
where maximum power is produced @ Standard Test Conditions(STC).
This value can be found on the rating label on the back of
the module or on the technical data sheet provided by the
manufacturer.

Sometimes listed as Ipp on datasheets.
Imp Coefficient A/°C

Maximum(Peak) Power Current
Temperature Coefficient (amps/°C)

This is a not a required value.
Specify a value, if provide, for optimal results.

This value specifies how much the module Imp changes
with temperature. Units are usually specified in
milliamps per degree C or % of Imp per degree C.

Morningstar Product

System Info

Minimum Battery Voltage V

Minimum Battery Voltage

This is a required value

Specify the lowest voltage expected for the system battery. This value
may be determined by the LVD setpoint of the charge controller or the
cut-off voltage of the system load(s).

Suggested values:

Nominal Voltage Minimum Voltage

12 Volt 11.5 V

24 Volt 23.0 V

48 Volt 46.0 V

Record Low Temperature

Record Low Temperature

This is a required value

Specify the coldest ambient temperature
on record where the sytem is located

Maximum Battery Voltage V

Maximum Battery Voltage(volts)

This is a required value.

Specify the highest expected battery voltage
This value is determined by the equalization
voltage setpoint, compensated for temperature.
If unsure, use the suggested values below:

Nominal Voltage Maximum Voltage

12 Volt 15.5 V

24 Volt 31.0 V

48 Volt 62.0 V

Average High Temperature

Average High Temperature

This is a required value

Specify the average annual high temperature
for the system location