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Peak sun hours is one of the most important criteria to examine when considering installing a solar power system. Peak sun hours are different than total sunlight hours in a day because the strength of the radiation of the sun varies throughout the day. For example, during sunrise and sunset the solar insolation from the sun is less powerful than at noon. For a moment of sunshine to be considered a peak sun hour the intensity needs to be at least 1 kilowatt per square meter. This means that a square meter of your solar panel should be receiving 1 kilowatt of energy from the sun. This number is used because it is an amount of light that allows a solar panel to produce output efficiently and not under perform due to lack of sunlight power.

Your latitude is an indicator of when the sunrises and sunsets and certain times of the year. If you live near the equator with a latitude of near zero, the sun will rise and set close to the same time all year resulting in consistent total sunlight hours per day. If you live near the poles, the time of sunrise and sunset will vary dramatically with each season, resulting in long days for part of the year and very short days at other times. So, locations closer to the equator will have more consistent amounts of peak sun hours throughout the year than locations closer to the poles.

You will notice that the average peak sun hours for Gratiot change based on the type of panel being used. The reason for this is quite simple. A fixed panel does exactly what it sounds like, remains fixed in one position at all times. A 1-axis and 2-axis panels have axis that allow them to rotate. The 1-axis rotates with the sun's daily east to west movement while a 2-axis also adjusts for seasonal changes.

Another reason to consider average peak sun hours is because weather can dramatically affect the day-to-day output of solar panels. It goes without saying that a dark stormy day will produce less output than a clear sunny day. Looking at a yearly average helps account for these daily variables.

Using the latitude of Gratiot along with historical data of sunlight and weather patterns we can estimate that a fixed mounted solar panel will receive an average of 4.5 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 5.2 hours and 5.7 hours, respectively.