Solar Panel Calculator

Estimate solar panel output, system size, number of panels, roof area, daily kWh, monthly kWh, yearly kWh, electric bill offset, savings, and payback period. This calculator is useful for rough solar planning before getting a professional design.

Calculate Solar Panel Output

Daily solar kWh = system kW × peak sun hours × system efficiency.
Your result will appear here.

How the solar panel calculator works

System size:
The calculator multiplies panel wattage by panel count, then converts watts to kilowatts.

Solar production:
Daily kWh is estimated from system size, peak sun hours, and system efficiency.

Savings:
Solar kWh is multiplied by your electric rate to estimate monthly and yearly savings.

Why use a solar panel calculator?

A solar panel calculator helps estimate how many panels you may need and how much power they may produce before you request quotes.

It can help with home solar, RV solar, cabin solar, farm solar, shop solar, battery planning, electric bill offset, and payback estimates.

What your result means

Your result shows estimated solar system size, panel count, daily kWh, monthly kWh, yearly kWh, usage offset, roof area needed, monthly savings, yearly savings, installed cost, incentive estimate, net cost, payback period, and long-term savings.

Solar panel calculator formulas

Frequently asked questions

How do I calculate solar panel output?

Multiply system size in kW by peak sun hours per day, then multiply by a system efficiency factor to account for real-world losses.

How many solar panels do I need?

Divide your target daily kWh by the estimated daily kWh produced by one panel. Round up to the next whole panel.

Why does solar output change?

Solar output changes with sunlight, shade, panel angle, temperature, inverter efficiency, roof direction, dust, snow, clouds, and seasonal daylight.

Can this calculator design my final solar system?

No. This calculator gives a planning estimate. Final solar system design should account for utility rules, permits, roof structure, panel layout, inverter sizing, wire sizing, rapid shutdown, batteries, code requirements, and installer recommendations.