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Engineering Calculator · 122

PV String Voltage & Parallel Current Calculator

Calculate series-string voltage, a linear cold-Voc estimate and parallel reference currents for identical PV modules and strings.

Electrical continuity
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Live calculation

Enter the known values.

Units remain visible beside every field and result. Change any input to recalculate immediately in your browser.

01

Inputs

02

Results

Linear temperature-corrected string Voc442V
String Voc at reference conditions400V
String Vmp at reference conditions330V
Parallel-array Imp at reference conditions19A
Parallel-array Isc at reference conditions20A
Other strings’ summed reference Isc10A

Formula
Voc,cold=NsVoc,ref[1+βVoc100(Tmin⁡−Tref)]V_{\mathrm{oc,cold}}=N_sV_{\mathrm{oc,ref}}\left[1+\frac{\beta_{\mathrm{Voc}}}{100}(T_{\min}-T_{\mathrm{ref}})\right]Iarray=NpImoduleI_{\mathrm{array}}=N_pI_{\mathrm{module}}

The calculation runs locally in this browser. Values are not submitted or stored by this tool.

Direct answer

What this result means

Series-connected matched modules add voltage; parallel matched strings add current. Cold string Voc uses the module’s signed Voc temperature coefficient and minimum cell temperature. Ten 40 V modules with −0.3%/°C coefficient at −10°C instead of 25°C give a linear estimate of 442 V open circuit.

PV String Voltage & Parallel Current Calculator engineering relationship diagramModule datasheet Voc, Vmp, Isc and Imp must share reference conditions. Ns counts modules per series string and Np counts identical parallel strings. The coefficient is entered as signed percent per degree Celsius. The other-string current is (Np − 1)Isc at the reference conditions, not a complete reverse-fault or fuse-sizing calculation. This dedicated schematic represents pv matched series strings parallel bus and is not to scale.Σ ISeries modules N_sParallel matched strings N_pCold VocMATCHED MODULES AND STRINGS · TOOL 122Module reference VocLinear temperature-correct…
Calculator-specific engineering relationship diagram — schematic, not a product drawing, and not to scale.

Formula & theory

Make the assumptions visible.

Module datasheet Voc, Vmp, Isc and Imp must share reference conditions. Ns counts modules per series string and Np counts identical parallel strings. The coefficient is entered as signed percent per degree Celsius. The other-string current is (Np − 1)Isc at the reference conditions, not a complete reverse-fault or fuse-sizing calculation.

Calculation relationship
Voc,cold=NsVoc,ref[1+βVoc100(Tmin⁡−Tref)]V_{\mathrm{oc,cold}}=N_sV_{\mathrm{oc,ref}}\left[1+\frac{\beta_{\mathrm{Voc}}}{100}(T_{\min}-T_{\mathrm{ref}})\right]Iarray=NpImoduleI_{\mathrm{array}}=N_pI_{\mathrm{module}}

Module datasheet Voc, Vmp, Isc and Imp must share reference conditions. Ns counts modules per series string and Np counts identical parallel strings. The coefficient is entered as signed percent per degree Celsius. The other-string current is (Np − 1)Isc at the reference conditions, not a complete reverse-fault or fuse-sizing calculation.

Variables

NpIdentical parallel stringscount
Tmin, TrefMinimum and reference cell temperatures°C

Use sequence

From measurement to review

  1. Obtain one compatible module datasheet and define identical series and parallel counts.
  2. Enter reference electrical values, the signed relative Voc coefficient and the applicable cell temperatures.
  3. Review voltage limits, current corrections, reverse-current limits and protection with the applicable system design procedure.

Limits

What this calculation does not confirm

  • Strings have identical matched modules and series counts; shading, mismatch, bypass action and operating-point variation are excluded.
  • Cold Voc uses a linear manufacturer-coefficient model. Tolerance, irradiance effects and required design corrections need separate review.
  • Other-string Isc is a reference-condition arithmetic sum. It is not a worst-case fault current, protective-device rating or approval of connectors, cables or inverters.

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Calculator FAQ

Use the number without losing the engineering context.

These answers clarify what the tool calculates and where a product-specific review still begins.

01Calculator guidanceDo series PV modules add current or voltage?

Matched series modules add voltage while carrying the string current. Matched parallel strings add current at a common voltage. These simple relationships assume compatible modules and operating conditions.

02Calculator guidanceCan other strings’ summed Isc be used directly to select a PV fuse?

No. It is an arithmetic reference-condition contribution. Required current corrections, module reverse-current limits, other backfeed sources, protective-device characteristics and the applicable design rules must be assessed separately.

03Calculator guidanceWhy must the Voc temperature coefficient keep its sign and unit?

A negative relative coefficient normally increases Voc when cells get colder. Entering its unsigned magnitude or an absolute V/°C coefficient into this percent-based formula changes the result incorrectly.

Product selection support

Connect the calculation with cable-entry product options.

Bepto Cable Glands can help relate a preliminary result to the product family and current model information for your application. You can start with the details you have; a complete drawing package is not needed to ask a question.

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