Solar Panel Output Calculator
Estimate the electricity a solar array produces. Enter the system size in kW, or the panel wattage and count, then add your peak sun hours and a performance ratio.
How to estimate solar panel output
- Enter your system size in kW, or a single panel wattage and the panel count.
- Enter the average peak sun hours per day for your location.
- Set the performance ratio for losses (around 0.75 is typical).
- Read the estimated daily, monthly and yearly production in kWh.
Examples
5 kW system at 5 peak sun hours
5 kW, 5 sun-hours/day, performance ratio 0.75
18.75 kWh/day, about 570.31 kWh/month, 6,843.75 kWh/year
Frequently asked questions
What are peak sun hours?
Peak sun hours are the number of hours per day that sunlight averages 1000 watts per square meter. Most regions see about 3 to 6.
What is a performance ratio?
It captures real-world losses from heat, wiring, inverters and dirt. A figure of 0.75 means the array delivers about 75 percent of its ideal output.
How do I find my system size in kW?
Multiply the wattage of one panel by the number of panels, then divide by 1000. Twelve 400 watt panels make a 4.8 kW system.
How are monthly and yearly figures calculated?
Yearly is the daily output times 365 days. Monthly is the yearly total divided by 12, so each month is treated equally.
Will my output match this every day?
No. Real output rises and falls with weather, season, shading and panel angle. This gives a steady long-run average to plan with.
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