How to Calculate Daily kWh from Your Solar Panels

Solar panels are a powerhouse of renewable energy, but figuring out exactly how much electricity they generate daily can feel overwhelming. In this guide, we’ll simplify the math, provide a handy formula, and break down solar panel kWh production based on size, location, and sunlight. Whether you’re sizing a system for your home or just curious about solar potential, you’ll walk away with clear answers.

Key Factors That Determine Solar Panel kWh Production

Two variables dictate how much energy your solar panels produce:

1. Solar Panel Wattage:

Higher-wattage panels generate more kWh. Common sizes include 100W (small setups), 300-400W (residential), and 500W+ (commercial systems).
Example: A 500W panel produces 50% more energy than a 250W panel under the same conditions.

2. Peak Sun Hours:

This measures daily sunlight intensity that is usable for solar power. In the U.S., averages range from 3 hours (Alaska) to 7 hours (Arizona).
Pro Tip: California (5.38 hours) and Texas (4.92 hours) lead in solar adoption due to abundant sunshine.

Solar Panel kWh Calculator: The Simple Formula

Calculate daily kWh output with this equation:

0.75 Factor: Accounts for 25% system losses (inverter efficiency, wiring, battery storage).
Divide by 1000: Converts watt-hours (Wh) to kilowatt-hours (kWh).

Quick Example: Let’s say you want to know how many kWh does a 300-watt solar panel produce per day. You live in Texas, and you can use the average yearly 4.92 peak sun hours per day sun irradiance. Let’s insert these figures in the equation like this:

Daily kWh Production (300W, Texas) = 300W × 4.92h × 0.75 / 1000 = 1.11 kWh/Day

We can see that a 300W solar panel in Texas will produce a little more than 1 kWh every day (1.11 kWh/day, to be exact).

0.75 Factor: Accounts for 25% system losses (inverter efficiency, wiring, battery storage).
Divide by 1000: Converts watt-hours (Wh) to kilowatt-hours (kWh).

Peak Sun Hours Explained

“Peak sun hours” quantify usable sunlight intensity, not just daylight duration. For example:

1 Peak Sun Hour = 1 hour of sunlight at 1,000W/m² irradiance (the standard for panel testing).
5 Peak Sun Hours = 5 hours of equivalent optimal sunlight.

State-By-State Peak Sun Hours Chart

Location	Average Peak Sun Hours (PSH)
Alabama	3.5 – 4
Alaska	2 – 3
Arizona	7 – 8
Arkansas	3.5 – 4
California	5 – 7.5
Colorado	5 – 6.5
Connecticut	3
Florida	4
Georgia	4 – 4.5
Idaho	4 – 4.5
Illinois	3 – 4
Indiana	2.5 – 4
Iowa	4
Kansas	4 – 5.5
Kentucky	3 – 4
Louisiana	4 – 4.5
Maine	3 – 3.5
Maryland	3 – 4
Massachusetts	3
Michigan	2.5 – 3.5
Minnesota	4
Mississippi	4 – 4.5
Missouri	4 – 4.5
Montana	4 – 5
Nebraska	4.5 – 5
Nevada	6 – 7.5
New Hampshire	3 – 3.5
New Jersey	3.5 – 4
New Mexico	6 – 7
New York	3 – 3.5
North Carolina	4 – 4.5
North Dakota	4 – 4.5
Ohio	2.5 – 3.5
Oklahoma	4.5 – 5.5
Oregon	3 – 5
Pennsylvania	3
Rhode Island	3.5
South Carolina	4 – 4.5
South Dakota	4.5 – 5
Tennessee	4
Texas	4.5 – 6
Utah	6 – 7
Vermont	3 – 3.5
Virginia	3.5 – 4
Washington	2.5 – 5
West Virginia	3
Wisconsin	3.5
Wyoming	5.5 – 6

Source: Global Solar Atlas, National Renewable Energy Laboratory, and Turbine Generator.

Key notes:

Seasonal Impact: Summer sun can boost production by 40% compared to winter.
Regional Differences: A 5kW system in Arizona generates 33.6 kWh/day vs. 18.95 kWh/day in New York.

Maximizing Your Solar Output

1. Tilt and Angle: Adjust panels to match your latitude for optimal sun exposure.

2. Reduce Shading: Trim trees or use micro-inverters to minimize energy loss.

3. Efficient Inverters: Pair panels with high-efficiency inverters (95%+).

4. Battery Storage: Store excess energy for cloudy days or nighttime use.

In a nutshell

Solar panel kWh production hinges on your location’s sunlight and panel wattage. Use our formula, chart, and state data to estimate your system’s potential.

Ready to take the next step? Explore our Popular Solar Kits or Design Your System to tailor a system to your needs.