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Peak sun hours are a vital measurement to understand when considering the installation of solar panels. Peak sun hours are not the same as total sunlight hours because not every hour of sunlight during the day has enough strength and solar insolation to qualify as a peak sun hour. The rule of thumb is that a peak sun hour is when the intensity of the sun that is hitting your solar panel is providing at least 1,000 watts per square meter. This is an arbitrary number, but it is a number where most solar panels will be producing an efficient output and not underperforming due to sunshine that is not strong enough or direct enough.

If you’re using a fixed axis and fixed tilt solar panel, the ideal angle of the panel mount should be set at an angle equal to or close to the latitude of the location of the panel. Latitude is a valuable measurement to use when figuring how many daylight hours and the angle of the sun in the sky for your location. Since at locations with a higher latitude the sun will find itself at more variable angles in the sky throughout the year it is important to set the angle of the panel correctly and efficiently capture more peak sun hours. In the Northern Hemisphere the sun will be at lower angles in the Southern sky in the winter, and higher angles during the summer months, so the angle of the panel is crucial when trying to maximize output.

You will notice the difference in peak sunlight hours depending on the panel type. The more flexibility the solar panel has the efficient it can be throughout the day and the year. A fixed solar panel remains in the same position at all times. A 1-axis panel follows the sun throughout the day as it moves through the sky and eventually sets. A 2-axis panel not only tracks the daily movement, but also adjusts based on the sun's changing position in the sky throughout the year as the seasons change.

Peak sun hours are greatly affected by weather patterns. Cloud coverage is a huge factor in peak sun hours per day because heavy cloud coverage will diminish the power of the solar insolation. You can use historical climate data to estimate average cloud and weather coverage, but it will obviously vary slightly from year to year.

Using the latitude of Sublette along with historical data of sunlight and weather patterns we can estimate that a fixed mounted solar panel will receive an average of 4.8 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 5.8 hours and 6.4 hours, respectively.