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If you put your solar powered math calculator in your backpack it will turn off from the lack of sunlight needed to power the device. As you slowly open your backpack and begin to let sunlight in, the calculator will eventually turn on when the amount of sunlight is enough to power the calculator. Similarly, peak sun hours refer to the hours of they day where the sunlight is strong enough to power a solar panel. This is different from total sunlight hours, which is simply the amount of hours in a day when there is any sunlight.

Knowing the latitude of Paauilo 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.

Throughout the day the sun obviously moves throughout the Paauilo sky. The suns position in the sky also changes throughout the year with the seasons. A fixed solar panel does not accommodate for these changes. However, a 1-axis panel rotates and follows the sun’s path during the day. A 2-axis panel both follows the sun’s daily path as well as the seasonal differences

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.

We can take the latitude of Paauilo and use that number to know the amount of total sunlight hours in the region from sunlight to sunset and estimate that with a fixed solar panel, Paauilo will receive 5.4 average peak sun hours per day. This number can be increased to 6.6 hours by using a 1-axis tracking mount, or 8.3 hours from a 2-axis tracking mount.