Shall We Talk About Solar Energy? Have You Ever Wondered How Many kWh a 665W Solar Panel Can Generate? The Answer Depends on a Few Factors, and Today I Will Explain It to You.
To find out how many kWh a 665W solar panel generates, we need to consider two factors in addition to the panel’s power: the average irradiation of the installation site and the efficiency of the solar energy system.
The average irradiation varies by region and is essential for calculating energy production. For example, in Belo Horizonte, the average daily irradiation is 5.4 kWh/m². Now, let’s understand how these numbers combine to calculate energy generation.
Factors Influencing Solar Energy Generation
1. Solar Irradiation: The “power of the Sun” varies depending on the location. In the North of Brazil, the irradiation is one way, while in the South it is another. In BH, we use an average of 5.4 kWh/m² per day. This value is crucial for determining how many kWh your panel will generate.
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2. System Efficiency: No system is 100% efficient. Losses can occur due to dirt, deviation from the ideal tilt angle, losses in wiring, among other factors. An average efficiency of 75% (or 25% loss) is used to ensure a conservative and realistic estimate.
Calculating Energy Generation from the 665W Solar Panel
Now, with all the factors defined, the formula for calculating the energy generated monthly is simple:
Monthly Energy Generated (kWh) = Panel Power (W) x Average Daily Irradiation (kWh/m²) x System Efficiency x 30 Days / 1000.
Let’s look at the numbers:
- Panel Power: 665W
- Average Daily Irradiation in BH: 5.4 kWh/m²
- System Efficiency: 75% (or 0.75)
Substituting the values:
Energy Generated = 665×5.4×0.75×30/1000
This results in approximately 80.80 kWh per month.
Difference by Location
Solar irradiation makes a huge difference! In São Paulo, where the average irradiation is 4.64 kWh/m² per day, the same 665W solar panel would generate about 69.4 kWh per month. In Brasília, with an irradiation of 5.45 kWh/m² per day, the generation would be approximately 81.55 kWh per month. See how location directly influences energy production?
To know how many kWh a 665W solar panel generates in your area, follow these steps: find out the average daily irradiation of your location, consider the system efficiency, and use the formula we showed. With that, you will have an accurate estimate of solar energy production. So, are you ready to invest in solar energy and make a difference for the planet?


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