he sun is shining all over the world, however, with a different intensity. A solar mapping tool might be indispensable for those who need to know how much sunlight their place receives. Let’s see what benefits it has to offer for those considering going solar.

What is a solar insolation map?

A sun map gives you information about solar resources in your area. A solar power map of a city, a state, or a country shows how much sunlight this place gets on average. For instance, a sun map created by the NREL1 illustrates the average daily amount of solar power across the U.S. measured in kilowatt hours per square meter. Another example of a sunlight map is Solar Mapper by SEIA 2.

When do you need a sun map?

Solar mapping tools can be handy in case you plan to purchase a solar power system. If you are aware of your area’s solar potential, you will be able to calculate the size of your photovoltaic system on your own using the simple formula: Average Daily Power Consumption ÷ Average Daily Peak Sun Hours ÷ Solar Panel’s Efficiency = Number of Panels your house requires to meet its power needs.

What is a peak sun hour?

You might receive about 8 hours of sunlight at your location each day. However, this doesn't mean that your location experiences 8 peak sun hours. The solar term "peak sun hour" is used to describe the intensity of sunshine rather than its duration. In scientific terms, one peak sun hour is equivalent to one hour of solar irradiance averaging 1,000 watts per square meter.

Why do peak sun hours vary by area?

Sunlight is more intense in regions closer to the equator, which is why U.S. southern states generally experience more peak sun than northern territories. However, proximity to the equator is not the only factor that affects the strength of solar radiation. In southwestern states, there are more cloud-free days, improving the conditions for solar power generation.

What are the average peak sun hours in my state?

In the USA, most states experience between 3 and 5 peak hours of sunlight per day. The table below shows the typical solar radiance of 10 randomly selected US states 3.


Solar insolation (PHS)


2-3 peak sun hours


7-8 peak sun hours


5-7,5 peak sun hours


3-4 peak sun hours


4-4,5 peak sun hours


6-7.5 peak sun hours

New York

3-3.5 peak sun hours

South Carolina

4-4.5 peak sun hours


6-7 peak sun hours


5.5-6 peak sun hours

Still, the average is only an average. Using one of the online solar mapping tools, you can easily find more precise info on solar insulation and peak sun hours based on your address (ZIP code).

How many PSH should you have to go solar?

If your home in the United States receives at least 4 peak sun hours per day, installing solar panels is definitely a worthwhile investment. However, even if the sun map shows that you receive less than 4 hours of direct sunlight, you can still reap the benefits of solar power. There are a lot of other factors that influence the efficiency of solar equipment, including its type and size, orientation and angle, etc. So before making the decision to invest in PV panels, it is important to consult with a solar installer who can help assess the feasibility and cost savings in your specific situation.




May 29, 2023

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