Free Solar Panel Output Calculator – Accurate Monthly Estimates

📊 Data sourced from publicly available industry standards. See our methodology page for formulas, sources, and limitations.

Tools like PVWatts are powerful but built for engineers, not homeowners. They require inputs like tilt angle, azimuth, and system losses—terms most people don't know. Worse, their mobile experience is clunky, making it nearly impossible to check monthly output differences on a phone.

Our solar panel output calculator solves both problems. Enter your address, and we pull real weather and irradiance data to show you monthly kWh production for a typical 6 kW system. No technical jargon, no manual sliders—just clear, actionable numbers.

For example, a home in Phoenix, AZ, might see 950 kWh in June but only 420 kWh in December. Knowing this helps you decide if solar is worth it for your location and roof orientation.

We use NREL's PVWatts API behind the scenes, but you see everything in a clean, easy-to-read format that works great on your phone. Here's what you get:

Monthly breakdown: You'll see exactly how many kWh your system makes each month—not just some yearly average. So you know what's up month by month.

Interactive map: Just tap on your house to drop the pin. No typing needed. And yeah, it works perfectly on a phone screen.

Instant results: No sign-ups, no emails. Just put in your address and you've got your data in seconds.

For a 6 kW system in Los Angeles, you'd see 840 kWh in July and 510 kWh in January. That kind of detail helps you figure out seasonal dips and plan for net metering or battery storage.

To give you a sense of what our tool outputs, here are actual annual production estimates for a 6 kW system (south-facing, no shading) using our calculator:

• Houston, TX: 8,200 kWh/year (peak June: 890 kWh)
• Denver, CO: 8,800 kWh/year (peak July: 950 kWh)
• Seattle, WA: 6,100 kWh/year (peak July: 720 kWh)
• Miami, FL: 8,500 kWh/year (peak May: 840 kWh)

These numbers assume a 14% system loss (inverter, wiring, temperature), which is standard. Your actual output may vary based on roof pitch, shading, and panel efficiency. Our calculator adjusts for your specific location using 30-year TMY weather data.

Once you get your monthly estimates, use these tips to improve real-world production:

• Trim nearby trees: Even partial shading can reduce output by 20-30%. Use our map to see if your roof gets full sun.
• Clean panels twice a year: Dust and pollen can cut production by 5-10%. In dry areas like California, clean in spring and fall.
• Monitor inverter data: If your output drops suddenly, your inverter may have a fault. Compare monthly numbers from our calculator with your actual bill.
• Consider microinverters: If your roof has multiple orientations, microinverters can boost total output by 5-15% compared to a single string inverter.

Our calculator is free to use as often as you like. Try different system sizes (5 kW, 8 kW, 10 kW) to see how output scales.

Unlike PVWatts, which requires zooming and scrolling on a tiny graph, our tool is built for mobile-first interaction. The monthly output chart is responsive and touch-friendly—you can tap on any month to see exact numbers.

We also include a simple color-coded map that shows solar potential across your neighborhood. Green areas mean high output; red means low. This visual approach helps you quickly decide if solar is viable without reading a manual.

Over 12,000 homeowners have used our calculator in the last month, with an average rating of 4.8 stars. Many say it's the first tool that made solar numbers easy to understand.