Solar PV Size Calculator Online

Last updated on by Editorial Staff

Solar PV Size Calculator

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Quick Guide to Use Solar PV Size Calculator

  • Enter your monthly energy consumption in kilowatt-hours (kWh).
  • Input the average peak sun hours per day for your location.
  • Provide the derate factor (a decimal value representing system losses, also called solar panel efficiency).
  • Click the “Calculate” button to determine the recommended Solar PV Size in kW.
  • Use the “Reset” button to clear the fields and start a new calculation.


Solar PV size in kW = Daily energy consumptions in kWh / (peak sun hours per day X derate factor in decimals)

Where, daily energy consumption = monthly energy consumption kWh/ 30days

What is the Solar PV Calculator?

The Solar PV Calculator is a tool designed to estimate the required size of a photovoltaic (PV) solar system based on monthly energy consumption, peak sun hours, and a derate factor.

It assists users in planning solar installations for optimal energy production.

Who Can Use This Calculator?

This calculator is useful for homeowners, businesses, and individuals considering solar panel installations. It caters to those interested in understanding the approximate size of a solar PV system needed to meet their energy demands.

Sectors That Can Use This Calculator

  • Residential
  • Commercial
  • Industrial

Benefits of Using This Calculator

  • Precision: Obtain a more accurate estimate of the solar PV size needed for your energy requirements.
  • Cost-Efficiency: Plan your solar investment more effectively, optimizing for cost and performance.
  • Sustainability: Contribute to environmental sustainability by adopting solar energy solutions.


Can I use this calculator for any location?

Yes, you can use it globally. Ensure to input accurate values, especially for peak sun hours based on your specific geographical location.

What is the derate factor?

The derate factor accounts for system losses due to various factors like shading, inverter inefficiencies, etc.

Why is monthly consumption used in the calculator?

Monthly consumption provides a comprehensive overview. Daily consumption is derived by dividing it by 30 for a standard month.


In conclusion, the Solar PV Calculator is a crucial tool for anyone considering a solar installation. By accurately estimating the required system size, users can make informed decisions, contributing to a sustainable and cost-effective energy future.