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The average amount of peak sun hours in a day is a different and more useful number as it relates to solar panels than total sun hours. Total sun hours are exactly what you would expect; the total amount of hours that the sun is out during a 24 hour period. Peak sun hours, on the other hand, are the total number of hours in a day where the sunshine is strong enough to to be absorbed and used by solar panels. Sunlight early in the morning or late at night is often not strong enough to count toward peak sun hours. Because of this, total sun hours will always be more than peak sun hours. Looking at the average peak sun hours in Des Moines throughout the year can help you better estimate the amount of solar panels you will need to power your business or home.

Although you can easily predict sunrise and sunset hours each day to the minute, looking at latitude can help with your solar planning. The closer you get to the equator the closer your latitude gets to zero. Sunlight hours on the equator are consistent throughout the entire year. Places further from the equator can have large variance in daily sunlight. For example higher latitudes can have very long summer days with lots of sunlight and very dark winters. The latitude of Des Moines is 47.4.

Since a fixed solar panel is set in one position it is ideal to place it at an angle that will expose the panel to the most sunlight throughout the year. This angle is generally the same angle of your latitude which is 47.4 for Des Moines. You do not need to strategically place a 1-axis or 2-axis panel as much as you do a fixed panel. A 1-axis panel follows the movement of the sun during the day. Additionally, a 2-axis panel also adjusts for the suns various positions in the sky throughout the year.

Although weather predicting technology has greatly evolved over time, it is still a rather unpredictable factor that will affect the amount of peak sun hours your solar power system will receive. Cloudy days for example will usually have lower peak sun hours that a clear sunny day. And areas that usually have more average sunny days per year will probably have higher peak sun hours that areas that are often overcast or stormy.

Using the latitude of Des Moines along with historical data of sunlight and weather patterns we can estimate that a fixed mounted solar panel will receive an average of 3.7 hours per day in this area. That number can be increased with better technology including add a 1-axis or 2-axis tracking mount, which would increase the average peak sun hours per day to 4.7 hours and 5.1 hours, respectively.