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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.

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.

Depending on your output needs, to get more out of your solar panels you can either upgrade your technology, buy more panels, or buy different tracking type panels. A fixed solar panel remains fixed at one angle throughout the year. A 1-axis panel will produce more output because it follows the path of the sun from sunrise to sunset to maximize sun exposure. Even more productive is a 2-axis panel that not only follows the sun's path throughout the day, but also accounts for the more subtle sun changes throughout the year with the different seasons.

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.

In The Dalles you can look at the average peak sun hours of a fixed solar panel mount, which will be 3.9 hours. This number iis an estimate based on data of previous years. With a tracking mount in The Dalles you could theoretically increase the amount of peak sun hours per with a 1-axis mount, and get 4.9 hours, or a 2-axis mount and potentially increase your average to 6.1 hours.