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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.

Although you can easily predict sunrise and sunset hours each day to the minute, looking at latitude can help with your solar planning. The closer you get to the equator the closer your latitude gets to zero. Sunlight hours on the equator are consistent throughout the entire year. Places further from the equator can have large variance in daily sunlight. For example higher latitudes can have very long summer days with lots of sunlight and very dark winters. The latitude of Ho’olehua is 21.2.

They type of solar panel you use has an affect on the average peak sunlight hours. Some panels allow for movement, so they can track the sun as it rises in the east and sets in the west, or as the seasons change and the sun's path changes. A fixed panel remains fixed and does not have the ability to rotate, whereas a 1-axis and 2-axis panel can adjust with the sun.

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.

For a fixed mounted solar panel in Ho’olehua, meaning that the solar panel will not track the sun in the sky, once can expect about 5.5 average peak sun hours per day. A 1-axis mount would increase this number to 7 hours per day because the panel would be facing the sun throughout the day. A 2-axis system that tracks the sun in the sky every day of the year would get approximately 8 hours per day in Ho’olehua.