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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.

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.

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 39.3 for Roanoke. 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.

Weather is one of the major culprits that will cause inconsistent total peak sun hours for any given day. The sunrise and sunset will always be predictable every day, but the weather is hard to predict and cloud coverage can greatly diminish the efficiency of a solar power system on any given day. On the bright side, a location that is known to have cloudy weather a majority of the year could have unexpectedly more sunny days, so it can go both ways.

Since we know the latitude of Roanoke we can take the average amount of total sunlight hours and estimate that with a fixed solar panel there would be an average of 4.9 peak sun hours per day. 6.4 hours per day with a 1-axis tracking mount that tracks the sun from sunrise to sunset, and 6.6 hours with a 2-axis tracking mount that tracks the sun everywhere in the sky.