What is Peak Sun Hours?

In the course of designing an off-grid solar street lighting system, you’re often faced with an initial challenge of factoring the Peak Sun Hours of your location to experience maximum energy from your solar PV system.

If you’re not a PV technical personnel, understanding the peak sun hours and factoring it could be a difficult task.


Not to worry, in this post we’ve made the process as simple as possible for you to understand and apply the same to your PV installation.

To start,

Let us take a clear look at the term itself.

In simple terms,

Peak Sun Hours is the number of hours in a day when the Sun is at its maximum radiation.

The value of PSH varies per location, this is due to some certain factors that will be discussed shortly.

Before then, let’s break down the technicalities; because there’s more to the definition.

Average radiation from the sun measured on the surface of the earth during a clear day or noon is about 1000W/m2. (This value is standard for all PV tests & measurements.)

The number of hours in a day that a location experiences this value of radiation is called Peak Sun Hours.

1 Sun Hour is equivalent to 1000 W/m2 of the sun’s radiation collected in 1 hour.

3 Sun Hours is equivalent to 1000 W/m2 of the sun’s radiation collected in 3 hours.

The unit of measurement is therefore kWh/m2. It is also expressed as kWh/m2 day, this refers to the total Peak Sun Hours in a day.

As stated earlier,

Based on your location, there are couple of factors that affect the value of the Peak Sun Hours.