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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.

Knowing that the latitude of Annville is 40.3 can be helpful for understanding total sunlight hour variance. As you approach the equator latitude approaches zero. The closer the latitude is to zero, the more consistent the daily sunlight hours are throughout the year. Total sunlight hour consistency simply makes planning for your solar power needs easier, but it is certainly not a requirement.

The sun moves through the sky during the day, and changes positions in the sky throughout the year as the seasons change. A fixed solar panel remains fixed in position during this movement. So, although it is effective in capturing sunlight, a 1-axis or 2-axis panel can be more efficient. A 1-axis panel tracks the sun's movement throughout the day from sunrise to sunset. In addition to that, the 2-axis panel also accounts for the movement throughout the year.

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.

We can use previous years of data to estimate the amount of peak sun hours in Annville. A fixed tilt mount for example will receive 4 average hours per day. For more efficiency for your system in Annville you could use a 1-axis tracking mount and increase your daily peak sun average to 5.1 hours, or even further with a 2-axis panel to get an average of 5.3 hours.