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The average peak sun hours of Cairo is a crucial measurable component needed to efficiently implement a solar power system in a home or business. Put simply, peak sun hours are the hours of sunlight a day that are strong enough to be efficiently absorbed by solar panels and eventually turned into usable electricity. Not every minute of sunlight during a day is strong enough to be useful to a solar power system. Think about just minutes after the sunrises, which officially counts towards total hours of sunlight, but is usually too weak to be counted in peak sun hours because the strength of the solar insolation is not strong enough near the horizon to be absorbed and turned into electricity at an efficient rate. Times during the day like this, where the sun is out but not strong enough, are not counted as peak sun hours. In other words, the amount of peak sun hours in a location will theoretically always be less than total sunlight hours for a given day.

The latitude at the equator of the earth is zero degrees. This is where sunlight strikes the earth most directly. Due to the earth's curved shape, sunlight hits at a various angles depending on location. As latitude increases, the further you are located from the equator and more variance you see in sunlight hours. The latitude of Cairo is 40.8.

You will notice the difference in peak sunlight hours depending on the panel type. The more flexibility the solar panel has the efficient it can be throughout the day and the year. A fixed solar panel remains in the same position at all times. A 1-axis panel follows the sun throughout the day as it moves through the sky and eventually sets. A 2-axis panel not only tracks the daily movement, but also adjusts based on the sun's changing position in the sky throughout the year as the seasons change.

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.

Using the latitude of Cairo along with historical data of sunlight and weather patterns we can estimate that a fixed mounted solar panel will receive an average of 4.2 hours per day in this area. That number can be increased with better technology including add a 1-axis or 2-axis tracking mount, which would increase the average peak sun hours per day to 5.2 hours and 5.4 hours, respectively.