Solar Energy 101: Calculating Your Peak Sun Hours

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With energy costs going up every year, an increasing number of Americans are switching to solar power for both their businesses and homes. Apart from the long-term financial benefits of doing this, solar energy also has no negative impact on the environment.


When trying to determine how much solar energy will cost you, it is important to know how much sun is required for solar panels to work effectively and what is meant by the term ‘peak sun hours.’


How much sun is needed for solar panels?


To deliver the maximum power output, solar panels require direct sunlight. Although these panels can produce electricity in cloudy weather, the output will be much lower compared to a sunny day, typically between 25% and 40%.


To get the maximum benefit from available sunlight, your solar panels should face toward the south. They should also preferably be installed in an area where there are no buildings or trees that block out the sun for the biggest part of the day.


What is meant by Peak Sun Hours?


To begin with, the term ‘peak sun hours’ does not mean the same as ‘hours of daylight’. The former specifically refers to the amount of sun exposure that can be used for the efficient production of energy in a particular area during an average day. To be even more specific: a peak sun-hour refers to an hour during which the sunlight is intense enough to produce 1,000 watts per sq m.


The sun delivers different amounts of solar radiation at different times of the day, depending on whether there are clouds or not, where it is positioned in the sky, and related atmospheric circumstances. Factors that play a role include:


The season. There is an increase in peak sun hours during the summer months

What time of day it is. Noon is when peak solar radiation typically occurs. Closer to sunset or sunrise the sun’s angle causes the atmosphere to filter the sunlight more, reducing the amount of energy that gets through to the earth’s surface.

– Geography. Solar energy is at its highest closer to the equator. If you live far to the South, for example, your home might get around 7 hours of daylight, but the peak sun hours might not be more than 3 or 4.

– The weather. There are more clear, sunny days in areas like Florida and California than, for example, in Alaska.


Calculating your peak sun hours


In the biggest part of the US, the average number of peak sun hours per day is between 3 and 5. Many regions, however, get more sun during the summer months and less when winter arrives. Before deciding on whether solar panels will be a sound investment you should, therefore, know both the seasonal and yearly average peak sun hours in your part of the US.


You will find a variety of maps, lists, and charts on the Internet that will give you the monthly and seasonal averages for the amount of solar energy your location gets. This will help to calculate how many peak sun hours your solar panels are likely to get.


If you would like to calculate exactly how much solar energy your panels will get, one option is to buy an insolation meter. Place it in direct sunlight and wait until you get a reading. It will show information about the solar power supply, temperature, and light intensity. You can, of course, save yourself the money and effort by asking one or two local solar panel installers to do these calculations for you. They will also be able to help with calculating how much you could potentially save during a given year by switching to solar power.




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