# PV String Limit Checker

Compare a proposed series string against entered cold Voc and hot Vmp limits.

[Open this tool](https://whatson.pk/string-calculator/)

Category: Solar & Battery

Cold conditions can raise a panel string's open circuit voltage, while hot cells can reduce operating voltage.

Enter module coefficients and site temperature assumptions, then compare corrected string values with the entered inverter limits.

## Inputs and controls

* Panels in series (panels). Allowed range: 1 to 1000
* Module Voc at reference (V). Allowed range: 0.01 to 1000
* Module Vmp at reference (V). Allowed range: 0.01 to 1000
* Cold Voc multiplier (×). Allowed range: 1 to 3
* Cold Vmp multiplier (×). Allowed range: 1 to 3. Use the Vmp coefficient, independently of Voc.
* Hot Vmp multiplier (×). Allowed range: 0.01 to 1
* Absolute PV voltage limit (V). Allowed range: 0.01 to 10000
* Minimum operating MPPT voltage (V). Allowed range: 0.01 to 10000
* Maximum operating MPPT voltage (V). Allowed range: 0.01 to 10000

## How to use

* Enter panels in series, module Voc at reference and module Vmp at reference.

* Enter cold Voc multiplier, cold Vmp multiplier and hot Vmp multiplier.

* Enter absolute PV voltage limit, minimum operating MPPT voltage and maximum operating MPPT voltage.

* Select Calculate result. Read the returned values alongside the assumptions below before copying, exporting or acting on the result.


## Why use this tool

Cold and hot checks stay separate so a comfortable operating voltage does not hide excessive maximum voltage.


## Before relying on the result

Corrections must come from module coefficients and site temperatures. Equality with the absolute Voc limit is flagged with zero headroom. Current, startup voltage, string fusing and all equipment limits still need review.


## Tool limitations

Corrections must come from module coefficients and site temperatures. Equality with the absolute Voc limit is flagged with zero headroom. Current, startup voltage, string fusing and all equipment limits still need review.

## Questions

### Is equality with maximum Voc enough headroom?

No. Equality leaves zero headroom and is flagged. Appropriate equipment margins need design review.

### What should I check before using PV String Limit Checker?

Check Panels in series, Module Voc at reference, Module Vmp at reference and Cold Voc multiplier. Use the exact units shown beside the controls and replace any example values with your own inputs.

Source page last modified (UTC): 2026-10-01T18:56:36+00:00

This profile describes the tool. It does not execute it or supply a professional certification.