SolarBazaar

String Sizing Calculator

Engineering Tools

Panels per string within inverter voltage limits.

  • 100% Free
  • Instant Results
  • Accurate & Reliable
  • Data for Your Country
V

Panel open-circuit voltage (Voc), listed on the panel datasheet.

V

Panel voltage at maximum power (Vmp), listed on the panel datasheet.

V

Inverter's maximum DC input voltage, from the inverter datasheet.

V

Inverter's minimum MPPT operating voltage, from the inverter datasheet.

About this calculator

Panels per string within inverter voltage limits.

How the String Sizing Calculator works

The String Sizing Calculator asks for panel voc, panel vmp, inverter max DC voltage and MPPT min voltage, and returns min panels per string, max panels per string and cold-weather string voc. Accuracy follows directly from what you enter: use your own bills and measurements rather than typical values wherever you can, because national averages hide exactly the variation that decides whether a system pays back.

Results are calculated against assumptions for your country, including local tariffs, sun hours, typical installed costs and any incentives in force. Switching country in the header re-runs the calculation on that market's data, which is why the same inputs can produce very different answers in two countries.

Getting an accurate result

  • Use twelve months of electricity bills rather than one. Consumption swings seasonally, and a single winter or summer bill will bias the answer in one direction.
  • Enter your actual tariff, including standing charges and any time-of-use rates — the value of a generated kilowatt-hour is what you avoid paying, and that is rarely the headline rate.
  • Be honest about shade and roof orientation. A pitched roof facing away from the sun, or with a chimney over it for part of the day, can lose a fifth of its yield.
  • Check what your utility pays for exported power before assuming surplus has value; in some markets it earns close to nothing.
  • Re-run the calculation with a pessimistic set of inputs as well as a realistic one. If the case still holds at the pessimistic end, it is a robust one.

What this calculator cannot tell you

Estimates here are based only on the figures you enter and the country assumptions behind them. They do not account for the condition or age of your roof, structural or wind-load limits, the state of your consumer unit and earthing, permit and grid-approval timelines, scaffolding or access costs, or shading from anything a survey would pick up. Any of those can move the real number substantially.

Use the result to decide whether to get quotes and roughly what size to ask for. Treat an installer's surveyed quotation, not this page, as the figure to make a purchase decision on.

String Sizing Calculator — FAQs

Is the String Sizing Calculator free to use?

Yes. Every SolarBazaar calculator is free, needs no account, and returns results instantly. Your inputs are used to produce the estimate against your selected country's assumptions.

How accurate is this calculator?

It is as accurate as the inputs you give it. With real consumption figures from twelve months of bills, your actual tariff and an honest assessment of roof orientation and shade, results are typically a good planning-grade estimate. It cannot account for roof condition, structural limits, grid-approval delays or access costs, so a surveyed installer quotation will always be closer.

Does the String Sizing Calculator use local data for your country?

Yes — calculations run against country-specific assumptions covering tariffs, sun hours, typical system costs and incentives. Switching country in the header re-runs the same inputs against that market's data.

What information do I need before I start?

Have panel voc, panel vmp, inverter max DC voltage and MPPT min voltage to hand. Recent electricity bills cover most of it; the rest can be measured or estimated from your roof.

What else is in the Engineering Tools category?

Engineering Tools calculators on SolarBazaar cover the related questions you will hit next — the full set is linked from the calculators directory, and results carry across because they all use the same country assumptions.

Accurate. Reliable. Country-Specific.

Our calculators use real local data including tariffs, sun hours, system costs and incentives.

Learn More About Our Data

Disclaimer: This calculator provides estimates based on the information you provide. Actual results may vary. Please consult a solar professional for a detailed assessment.