Solar Panel String Calculator

Calculate optimal series and parallel wiring for your solar panels. Ensure your string voltage and current stay within inverter limits.

Total input current (23.0A from 2 parallel strings) exceeds inverter max current (15A). Reduce parallel strings or use a larger inverter.
Panels per String
10
range: 4–12
Number of Strings
2
parallel strings
String Voltage (Vmp)
417.0V
Voc: 495.0V
Total Input Current
23.0A
max: 15A

Wiring Configuration

10 panels in series x 2 strings in parallel = 20 panels total
String 1:P1—P2—P3—P4—P5—P6—P7—P8—P9—P10(10 panels)
String 2:P11—P12—P13—P14—P15—P16—P17—P18—P19—P20(10 panels)
All 2 strings connect in parallel to the inverter input

Electrical Summary

ParameterPer StringSystem TotalInverter LimitStatus
Voc (Open Circuit)495.0V495.0V600VOK
Vmp (Max Power)417.0V417.0V150–600VOK
Isc (Short Circuit)11.5A23.0A15AEXCEEDS
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How It Works

This calculator determines the optimal series/parallel wiring configuration for your solar panels based on your inverter's voltage and current specifications.

Max panels per string = floor(Inverter Max Voltage / Panel Voc). Min panels per string = ceil(Inverter Min Voltage / Panel Vmp). The optimal configuration maximizes string length within this range to minimize the number of parallel strings.

The calculator also verifies that the total parallel current (Isc x number of strings) stays within the inverter's maximum input current and flags any configuration issues with clear warnings.

Frequently Asked Questions

How many solar panels can I wire in series (one string)?

The maximum panels per string is determined by dividing your inverter's maximum input voltage by the panel's open-circuit voltage (Voc). For example, with a 600V inverter and 49.5V Voc panels, you can wire up to 12 panels in series (600 / 49.5 = 12.12, rounded down to 12).

What is the minimum number of panels per string?

The minimum is found by dividing the inverter's minimum MPPT voltage by the panel's maximum power voltage (Vmp). For example, with a 150V minimum and 41.7V Vmp panels, you need at least 4 panels per string (150 / 41.7 = 3.6, rounded up to 4) to reach the inverter's startup voltage.

What happens if my string voltage exceeds the inverter limit?

Exceeding the inverter's maximum input voltage can permanently damage the inverter and void your warranty. The open-circuit voltage (Voc) of your string — which occurs in cold temperatures with no load — must always stay below the inverter max. Cold weather increases Voc by roughly 0.3% per degree Celsius below STC (25C).

How do parallel strings affect inverter current?

When strings are wired in parallel, their currents add together. The total input current equals the short-circuit current (Isc) of one panel multiplied by the number of parallel strings. This total must not exceed the inverter's maximum input current rating.