Solar Array Current Calculator

Calculate array string current and voltage for cable and controller sizing.

About Solar Array Current Calculator

Voltage adds along a series string while current adds across parallel strings. Open circuit voltage is the figure that must stay within inverter and isolator ratings, and it rises in cold weather. String voltage in cold conditions can exceed 1,000 V and destroy an inverter, which is why Voc must be checked at the minimum expected temperature.

Formula

Solar Array Current

Series panels add voltage; parallel strings add current

Voc: Open circuit voltage, highest in cold conditions and used for insulation rating
1.25 factor: Safety margin required by wiring codes for continuous solar current

Worked example

With the default values below, Solar Array Current Calculator returns Array Current at Maximum Power of 20.800. Change any input above and every figure here is recalculated in your browser.

Inputs used

Panels in series per stringaccepts 1–40: 10
Strings in parallelaccepts 1–30: 2
Panel voltage at maximum powerminimum 0.1 V: 41.5 V
Panel current at maximum powerminimum 0.01 A: 10.4 A
Panel open circuit voltageminimum 0.1 V: 49.5 V

Results

Array Current at Maximum Power: 20.800 A
Array Voltage at Maximum Power: 415.00 V
Array Power: 8.6320 kW
String Open Circuit Voltage: 495.00 V
Design Current With 1.25 Factor: 26.000 A

Step by step

1Values used
2Solar Array Current
3Array Current at Maximum Power= 20.800 A
4Array Voltage at Maximum Power= 415.00 V
5Array Power= 8.6320 kW
6String Open Circuit Voltage= 495.00 V
7Design Current With 1.25 Factor= 26.000 A

Assumptions and limits

The result is derived only from the 5 inputs listed above. Anything not among them is not part of the calculation.
In particular, this calculator does not take inflation, tax, fees or charges or compounding frequency into account.
Figures are rounded for display to 4 decimal places, so totals built from several rounded parts can differ slightly from the unrounded arithmetic.

How these calculators are built and tested is described on the Methodology page. If a figure looks wrong, please report it.

Frequently Asked Questions

How is Solar Array Current calculated?

Series panels add voltage; parallel strings add current Voltage adds along a series string while current adds across parallel strings. Open circuit voltage is the figure that must stay within inverter and isolator ratings, and it rises in cold weather.

Why does Solar Array Current matter?

String voltage in cold conditions can exceed 1,000 V and destroy an inverter, which is why Voc must be checked at the minimum expected temperature.

What values do I need to enter?

This calculator takes 5 inputs: Panels in series per string, Strings in parallel, Panel voltage at maximum power, Panel current at maximum power, Panel open circuit voltage. The pre-filled defaults are a realistic starting point — replace them with figures from your own environment for a result you can act on.