Free Solar & Energy Calculators

Professional-grade tools for sizing solar systems, calculating payback periods, and making smarter energy decisions. No sign-up required.

☀️ Solar Sizing & Design

Calculate exactly what you need for your solar installation.

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Solar Panel System Size Calculator

Find out how many kW of solar panels you need based on your electricity usage, location, and goals.

Most Popular
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Solar Panel Output Calculator

Estimate daily and annual output for any solar panel based on wattage, sun hours, tilt, and efficiency.

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Roof Space Calculator for Solar

See how many solar panels fit on your roof and what system size is possible.

💰 Solar Financial

Understand the true cost and savings of going solar.

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Solar Payback Period Calculator

Calculate how long it takes for your solar system to pay for itself through energy savings.

Popular
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Solar Tax Credit Calculator (ITC)

Estimate your federal solar Investment Tax Credit under the Inflation Reduction Act — 30% through 2032.

2026 Updated
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Solar Savings Calculator

See how much you'll save monthly and over 25 years with a solar panel system.

🔋 Battery & Storage

Size your battery bank and backup systems correctly.

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Battery Bank Sizing Calculator

Calculate the battery capacity you need for off-grid or backup power systems.

Charge Controller Sizing Calculator

Size your MPPT or PWM charge controller for your solar array and battery bank.

⚡ Electrical

Wire sizing, voltage drop, and electrical design tools.

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Solar Wire Sizing Calculator

Calculate the correct wire gauge for DC and AC solar runs based on current, distance, and voltage drop.

Why Use PanelRig?

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Accurate Calculations

Our formulas follow NEC standards, NREL data, and manufacturer specs. We verify against PVWatts and real-world installations.

Instant Results

Every calculator updates in real-time as you type. No submit buttons, no waiting, no page reloads.

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Works Everywhere

Mobile-first design. Use our tools on the roof, at the panel, or at your desk. No app download required.

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100% Free

No sign-up, no paywall, no hidden features. Every calculator is completely free to use.

Disclaimer: Results are estimates. Actual solar production varies by location, weather, shading, and equipment. Consult a certified solar installer for system design. PanelRig may earn a commission from Amazon affiliate links at no extra cost to you.