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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 the latitude of Letts will help estimate average peak sun hours for your area. The latitude is used to accurately estimate the time of sunrise and sunset, thus giving you the total hours of daylight each day. Once you know the total hours of daylight, you can estimate the amount of peak sun hours based on a number of variables such as weather, time of year, the angle of the solar panel.

You will notice that the average peak sun hours for Letts 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.

The sun is a great ball of gas that rises and sets every day that the earth rotates while in orbit around the sun. Barring any major disasters this is a very predictable occurance every day. Latitude helps predict this even more, narrowing it down to the minute for sunrise and sunset. But some things aren’t as predictable that will greatly influence the efficiency of solar panels. Weather and cloud coverage for example can greatly diminish peak sun hours on any given day. Thick storm clouds will block a high percentage of the sun's rays, resulting in lower output of your solar panels. Weather needs to be factored into deciding when to use your system, or how much output one expects to get.

By taking the latitude of Letts one can get a close estimate of the amount of average peak sun hours per day for the geographical area. It varies with technology and the type of solar panel mount you use, but for a fixed mount solar panel in Letts one can expect close to 4.9 average peak sun hours per day. With a 1-axis tracking mount you would get 6.3 hours per day, and 6.8 hours per day with a 2-axis tracking mount that tracks the sun everywhere in the sky.