Home » Solar Turbine » Illinois » Foosland

Peak sun hours are a vital measurement to understand when considering the installation of solar panels. Peak sun hours are not the same as total sunlight hours because not every hour of sunlight during the day has enough strength and solar insolation to qualify as a peak sun hour. The rule of thumb is that a peak sun hour is when the intensity of the sun that is hitting your solar panel is providing at least 1,000 watts per square meter. This is an arbitrary number, but it is a number where most solar panels will be producing an efficient output and not underperforming due to sunshine that is not strong enough or direct enough.

The equator has a latitude of zero while Foosland has a latitude of 40.4. Any city located on the equator will receive the most sunlight throughout the year because the sunlight arrives at a perpendicular 90 degree angle to the earth at the equator. The further you are from the equator the more your daily sunlight hours can vary.

The sun moves through the sky during the day, and changes positions in the sky throughout the year as the seasons change. A fixed solar panel remains fixed in position during this movement. So, although it is effective in capturing sunlight, a 1-axis or 2-axis panel can be more efficient. A 1-axis panel tracks the sun's movement throughout the day from sunrise to sunset. In addition to that, the 2-axis panel also accounts for the movement throughout the year.

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.

In Foosland 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 5.7 hours if you are using a 1-axis panel, and to 5.8 hours if you upgrade to a 2-axis solar panel.