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The average peak sun hours of Northbrook 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 of the location is important for measuring peak sun hours. The latitude determines how much overall sunlight there will be in a day. With a given latitude, time and date, one can accurately determine when sunrise and sunset will occur. Areas with latitudes closer to the equator will have a more consistent range of solar insolation throughout the year. Whereas areas closer to the poles will have a greater variance during the summer and winter months due to their higher latitudes.

A tracking mount will increase the average peak sun hours for a solar power system. Think about a panel that is tracking the sun in the sky vs a panel that is fixed and not moving: you will see a higher efficiency ratio of productions. A 1-axis mount will track the sun from East to West from sunrise to sunset and move on a single axis of rotation. A 2-axis mount will track the Sun from East to West the same as a 1-axis mount would, but it will also track the angle of the sun in the sky as it slowly varies season to season. A 2-axis mount is more necessary in high latitude regions where the angle of the sun in the sky changes dramatically between each equinox.

Peak sun hours are greatly affected by weather patterns. Cloud coverage is a huge factor in peak sun hours per day because heavy cloud coverage will diminish the power of the solar insolation. You can use historical climate data to estimate average cloud and weather coverage, but it will obviously vary slightly from year to year.

Since we know the latitude of Northbrook we can take the average amount of total sunlight hours and estimate that with a fixed solar panel there would be an average of 4.6 peak sun hours per day. 5.9 hours per day with a 1-axis tracking mount that tracks the sun from sunrise to sunset, and 6.6 hours with a 2-axis tracking mount that tracks the sun everywhere in the sky.