What is PSH ?
Now that we have discussed the difference between power and energy we can better understand where each term is respectively applicable. Let us look at this into more detail with regard to solar energy.
Since we know,
power × time = energy
solar power × time = solar energy
Given that we have peak sun conditions of 1000 watts per square meter for one hour each day , then we would recognize this as “peak sun hour” or a “sun hour”.
Various different locations around the globe receive different amounts of solar energy. We often quantify the amount of energy a location has in average peak sun hours per day.
Peak sun hours per day is also often called insolation.
Insolation is incident solar radiation.
It is important to note the amount of sunlight your panels receives.
However, a more accurate representation of the amount of energy your panels can produce is known as peak sun-hours.
It is important to note that peak sun-hours are not to be confused with “hours of daylight.” Peak sun-hours refers specifically to how much solar energy is available in a particular area on a typical day.
The amount of solar radiation, or insolation, delivered by the sun varies throughout the day, based on the sun’s position in the sky, clouds, and other atmospheric conditions.
We have explored some of the factors here.
Time of Day: Peak solar radiation occurs at solar noon, which refers to the position of the sun when it is as the highest point in the sky. The low angle of the sun at sunrise and sunset means that the atmosphere filters the sunlight more and therefore, results in less energy being delivered to the earth’s surface.
Season: Sun-hours increase during the summer due to the sun’s higher position in the sky.
Geography: Solar energy increases near the equator, as it is closer to the sun.
While solar panels may receive an average 7 hours of daylight per day, the average peak sun-hours may actually be closer to 3 or 4.
For better understanding of how insolation values vary with changes in latitude and longitude, you can visit NASA’s website – https://power.larc.nasa.gov/data-access-viewer/