Solar Panel Size Calculator

Going solar starts with knowing how many panels you actually need — and the Solar Panel Size Calculator works that out from your real energy data. Enter your monthly electricity usage, bill offset goal, daily sun hours, system efficiency, and panel wattage to get the number of solar panels needed and your total system size. Secondary outputs include daily and annual energy production and the roof area required based on your chosen panel dimensions.

kWh

Check your recent electricity bills for average monthly usage

hours

Average peak sun hours per day in your location

Accounts for inverter losses, wiring, shading, etc.

meters
meters

Results

Solar Panels Needed

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Total System Size

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Daily Energy Production

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Annual Energy Production

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Roof Area Required

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Frequently Asked Questions

How many solar panels do I need for my home?

The number of solar panels needed depends on your monthly electricity usage, location's sun hours, and desired bill offset. Typically, a home uses 20-30 panels for complete energy independence.

What solar panel size should I choose?

Modern panels range from 300W to 500W. Higher wattage panels (400W+) are more efficient and require less roof space, but cost more upfront. Consider your roof space and budget when deciding.

How do I calculate solar panel output?

Solar panel output = Panel wattage × Daily sun hours × System efficiency × 365 days. A 400W panel in 5.5 sun hours with 85% efficiency produces about 681 kWh annually.

Why should I consider solar panels for home use?

Solar panels reduce electricity bills, increase home value, provide energy independence, and help the environment by reducing reliance on fossil fuels. Many areas also offer tax incentives for solar installations.

How much roof area do solar panels require?

Each panel typically requires 15-20 square feet (1.4-1.8 m²). A typical home system of 25 panels needs about 400-500 square feet of suitable south-facing roof space.

What factors affect solar panel efficiency?

Key factors include panel angle and orientation, shading, temperature, inverter efficiency, and wiring losses. System efficiency typically ranges from 75% to 90% depending on installation quality.

Can I offset 100% of my electricity bill with solar?

Yes, with proper system sizing you can offset 100% or more of your electricity usage. Net metering allows excess production to be fed back to the grid for credits during low-production periods.

How many sun hours does my location get?

Peak sun hours vary by location and season, typically ranging from 3-8 hours daily. Check local solar irradiance maps or weather data for your specific area to get accurate numbers.