How Much Solar Do You Need? Calculate Your System Size in 60 Seconds

You are researching solar. You have probably seen quotes ranging from 5 kW to 15 kW. Nobody can tell you the right size without looking at your roof and your electric bill.

Until now.

Why system size matters

A solar system that is too small will not cover your electric bill. A system that is too large wastes money on panels you do not need. The right size depends on three things:

1. Your monthly electricity usage (kWh)
2. Your roof area and orientation
3. Shading from trees, chimneys, or neighboring buildings

Most installers will guess at #2 and #3 during a sales call. They do not have satellite data in front of them. That is why quotes vary so wildly.

The average system size by state

| State | Average System Size | Average Annual Production | |-------|-------------------|------------------------| | California | 8.95 kW | 14,300 kWh | | Texas | 9.2 kW | 14,700 kWh | | Florida | 7.8 kW | 11,700 kWh | | Arizona | 8.5 kW | 14,450 kWh | | Nevada | 9.0 kW | 15,300 kWh |

These are averages. Your roof might need more or less. The only way to know for sure is to look at your actual roof from above.

How to estimate your system size yourself

Take your last electric bill. Find the total kWh for the month. Multiply by 12 for annual usage. Divide by the average production per kW in your state.

Example: You use 900 kWh per month in California. That is 10,800 kWh per year. California averages about 1,600 kWh per kW per year. 10,800 divided by 1,600 equals roughly 6.75 kW.

But this does not account for shading, roof angle, or obstructions. A 6.75 kW system on a shaded roof might only produce 4 kW worth of power.

Get the exact number with a satellite report

SolrScan uses satellite imagery to analyze your roof in real time. You get:

• Usable roof area in square feet
• Estimated system size in kW
• Shading analysis showing which parts of your roof get blocked and when
• Annual production estimate based on your location

It costs $19. The report is instant. No account needed. No sales call.

Get your roof analysis at solrscan.com

What to do with the report

Once you know your exact system size and production potential, you can:

• Compare installer quotes against a real baseline
• Negotiate pricing per watt with confidence
• Avoid installers who oversize or undersize your system
• Know upfront if your roof even qualifies

Do not wait for an installer to tell you what you need. Know first. Then shop.

Check your roof now for $19