Calculating solar panel output based on location and season?

Understanding Solar Irradiance

Solar irradiance is a measure of the amount of sunlight that hits the Earth’s surface per unit area. To determine the maximum possible solar panel output, you need to know your location’s solar irradiance levels. In the United States, the average solar irradiance varies from 150 to 300 watts per square meter (W/m²), depending on the region and time of year. For example, Phoenix, Arizona receives an average of 250 W/m², while Seattle, Washington receives an average of 120 W/m².

Calculating Solar Panel Output

To calculate solar panel output, you need to multiply the solar irradiance level by the surface area of the solar panels. A standard solar panel is approximately 1.6 meters by 1 meter (6.6 feet by 3.3 feet), or 1.6 square meters (17 square feet). If you have 1 kilowatt (kW) of solar panels, you can multiply the solar irradiance level by the surface area to determine the maximum possible output. For example, in Phoenix, Arizona, 1 kW of solar panels would produce approximately 400-500 kilowatt-hours (kWh) per day in the summer, while in Seattle, Washington, the same panels would produce approximately 200-250 kWh per day.

Accounting for Seasonal Variations

Seasonal variations in solar irradiance can significantly impact solar panel output. In the Northern Hemisphere, the sun is lower in the sky during the winter months, resulting in reduced solar irradiance. To account for these variations, you can use a solar panel’s nameplate rating and adjust it for the expected seasonal output. For example, a 1 kW solar panel rated for 400 kWh per day in Phoenix, Arizona might produce only 200 kWh per day in the winter months.