Vermont Solar Power Information & Peak Sun Hours
Solar Green Energy Summary for Vermont, Illinois
Lattitude: 40.2959
Sunlight
Fixed Tilt Sunlight Hours: 4.3 hours per day
1-Axis Tilt Sunlight Hours: 5.6 hours per day
2-Axis Tilt Sunlight Hours: 6.4 hours per day
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 Vermont is 40.3.
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.
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.
In Vermont the average yearly peak sun hours for a fixed tilt non-tracking solar panel mount is 4.3. This is for a fixed panel mounted at an angle that is equal to the latitude of the location for the entire year. The amount of peak sun hours increases to 5.6 hours if you are using a 1-axis panel, and to 6.4 hours if you upgrade to a 2-axis solar panel.