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.
Solar Panel System Size Calculator
Find out how many kW of solar panels you need based on your electricity usage, location, and goals.
Most PopularSolar Panel Output Calculator
Estimate daily and annual output for any solar panel based on wattage, sun hours, tilt, and efficiency.
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.
Solar Payback Period Calculator
Calculate how long it takes for your solar system to pay for itself through energy savings.
PopularSolar Tax Credit Calculator (ITC)
Estimate your federal solar Investment Tax Credit under the Inflation Reduction Act — 30% through 2032.
2026 UpdatedSolar 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.
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.
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?
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.
Works Everywhere
Mobile-first design. Use our tools on the roof, at the panel, or at your desk. No app download required.
100% Free
No sign-up, no paywall, no hidden features. Every calculator is completely free to use.