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What are Peak Sun Hours?

An alarm clock at the beach in the sun, representing the peak sun hours for maximum solar power production.
PublishedJune 29, 2021
UpdatedMay 17, 2024
AuthorCory O'Brien HeadshotCory O'BrienSenior Director - Growth MarketingEditorRyan Barnett HeadshotRyan BarnettSVP, Policy & New Market Development
In this article
What is the Definition of Peak Sun Hours?
What Should I Understand About the Peak Sun Hours?
What Are Peak Sun Hours by State?
How Will Peak Sun Hours Impact My Solar Panels?
How Much Sunlight Do My Solar Panels Need?
Ways To Take Advantage of Peak Sun Hours in Your Home
Key Takeaways

If you’re interested in going solar, you probably want to know if your area receives enough sunlight to generate the solar power your home needs. You may have heard that some hours of sunlight are better or more effective than others, that sunlight quality varies from one area to another, or that the energy-generating potential of sunlight changes from state to state.

Peak sunlight hours measure the intensity of sunlight and can help you estimate how much electricity your solar panels can produce. Specifically, each region has unique peak sunlight hours, which can help your decision-making process toward installing a solar panel system on your roof.

In this guide, we will teach you about peak sunlight hours so you can make the right choices about solar energy for your home.

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What is the Definition of Peak Sun Hours?

One peak sun hour is when the sun's intensity reaches an average of 1,000 watts of photovoltaic power per square meter. It’s not the same as one hour on the clock. Instead, it’s a measure of the amount of time the sun’s rays are most powerful in a given area, which means it’s the amount of time you can maximize electricity generation with your solar panels.

In scientific terms:

1 peak sun hour = 1000 W/m² (or 1 kW/m²) of sunlight per hour.

Peak sun hours are not the hours between sunrise and sunset. They refer directly to the solar insolation a particular area would receive when the sun's intensity is highest for a specific number of hours. Solar insolation is the amount of solar radiation that falls on the earth's surface in a given span of time.

Thus, it makes sense that the hours between midday and early afternoon are the peak hours for solar radiation since the sun is highest in the sky and solar panels receive the sun’s rays at the most direct angle. Conversely, peak sun hours don’t occur during sunrise and sunset because the sun is positioned at a lower angle in relation to solar panels.

In other words, if your location receives 7 kWh/m² of solar radiation over the course of one day, then you get 7 peak sun hours.

What Should I Understand About the Peak Sun Hours?

Knowing the peak sun hours for your region can help you determine the ideal size of the solar panel system for your roof. It can also help you understand how solar will be a worthy investment. Equally, if you plan to benefit from net metering, you need to figure out your area's peak sun hours to know if you can generate excess electricity.

To help you decipher what peak sunlight hours mean to solar installation, think of them as those weather insights you rely on to choose and plan your next trip. Peak sun hours help you recognize when your solar panels will be more productive so you can better plan for your long-term energy needs.

For example, if you know when your solar panel system will be most effective, you can calculate when and how you need to use energy in the home. This especially comes in handy regarding the extra energy you might be storing from those peak sun hours.

What Are Peak Sun Hours by State?

Each state in the USA has a unique number of average peak sun hours due to the variation in the different climate zones.

Chart showing the Peak Sun Hours for every state in the United States, identifying potential solar power generation.

Often, the number of peak sunlight hours increases the closer you are to the equator and generally during the summer months. The table below shows the peak sun hours by state across the country.

Table that outlines the peak sun hours for each state of the United States of America.

You can view this data on the detailed irradiance maps for the United States created by the National Renewable Energy Laboratory.

Solar companies use this factual information about the average daily peak sun hours your area gets, such as an insolation map, to help you make better decisions about the right solar panel system for your home in terms of the energy you need.

See how much you can save by going solar with Palmetto

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Step 02
My electric bill is $290/mo

How Will Peak Sun Hours Impact My Solar Panels?

Knowing your region's average peak sun hours can be a useful gauge of your home’s solar potential. Using the example below, let's see how you can use peak sun hours to calculate how much electricity you need your solar panel system to create:

  • Peak sun hours = 7
  • Your home used 25,000 kWh of electricity last year
  • 25,000 kWh / 365 days = 68.49 kWh per day
  • 68.49 kWh per day / 7 peak sun hours per day = 9.78 kWh
  • You should install a 10kW solar PV system

Your solar panels need the direct sunlight of peak sun hours to generate the maximum electricity possible for your home. However, you don’t need to move to a state with the highest number of peak sun hours to enjoy the perks of solar power. It just means that a home in Massachusetts that uses 25,000 kWh a year will need more solar panels in their rooftop array to generate that much electricity than a home in Arizona with the same amount of annual usage.

Other factors besides average daily peak sun hours impact your solar panel system energy production capacity, including:

  • Home consumption: Home energy consumption remains the biggest factor in determining the size of a solar panel system. Even if you live in an area with an abundance of peak sun hours, you still need the right amount of solar panels to generate the necessary power for your home.
  • Solar panel efficiency: This is the ability of a solar panel system to convert the absorbed sunlight into electricity. The average solar panel is roughly between 15% and 20% efficient, with high-quality solar panels in some cases exceeding 22% efficiency. The age of your solar panels and the type of material used to capture solar energy will determine the efficiency of your panels.
  • Storage capacity: To meet your energy usage needs, you can add battery storage to your solar panel system so you can prepare for times when your panels don’t generate enough electricity to meet your needs.
  • Future growth: You may decide to install more panels on your roof than you currently need if you anticipate your energy needs will increase in the future.

If you talk to the solar experts at Palmetto, you can be sure all details will be considered when we design a solar power system for your home. Our team of solar specialists will answer your questions and help you make the right solar choices for your needs.

How Much Sunlight Do My Solar Panels Need?

The short answer is “As much as they can get.” Solar panels are designed to generate electricity from sunlight. Even on a cloudy day, they will still generate some electricity.

But why then do you need to remember that peak sun hours vary if a solar panel system can still create power with any amount of sunlight? Because it’s important that your solar panels reach their maximum effectiveness when they are most productive.

Thus, peak sun hours help you calculate the size of the solar power system that’s ideal for your home.

Ways To Take Advantage of Peak Sun Hours in Your Home

Now that you know what peak sunlight hours are and why they should matter to you, let's learn how to get the most out of them, especially when the sun is strongest.

  • Store more electricity. Your solar panels will reach their maximum effectiveness when the sun's intensity is highest. They will likely produce excess electricity at this time. Installing a solar battery system can ensure you can use all the energy you generated.
  • Leverage net metering. If your solar panels are creating more electricity than you’re using, you can benefit from net metering. All of that extra energy will get sent to the electricity grid, and the credits you earn can be used to offset your utility bills. To learn more, check out our Guide to Net Metering for Home Solar.
  • Reduce your appliance usage during peak hours. To maximize the electricity generated during the peak sun hours for storage or net metering, you should look for opportunities to use less energy during peak hours and shift that usage to other parts of the day.

Key Takeaways

Knowing the peak sun hours for your area helps you design a solar panel system that will generate the electricity you need. You can also use that information to develop a system that will yield extra electricity for storage, future growth, and net metering.

Talk to Palmetto today to learn more about how your home can best utilize peak sun hours. Our experts can assist with your solar panel decisions by taking into account different factors, including your preferences and budget, to ensure you install the right solar panel system for your needs. Get started today with a free Solar Savings Estimate, and we'll do everything we can to make sure you take advantage of peak sun hours with a top-of-the-line solar power system.

See what solar can do for you:

My electric bill is $290/mo
About the AuthorCory O'Brien HeadshotCory O'BrienSenior Director - Growth Marketing

Cory brings over 8 years of solar expertise to Palmetto, and enjoys sharing that knowledge with others looking to improve their carbon footprint. A dog lover residing in Asheville, NC with his wife, Cory graduated from UCSB. If you run into him, ask him about the company he founded to rate and review beer!

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