What Are the Average Peak Sun Hours by State?
Aug 25th 2021
Do you remember learning about average peak sun hours in school? If you think back to your school-age days, you may remember sitting in science class learning about the relationship between the Earth and the Sun, but something as specific as average peak sun hours has probably left your mind.
As solar panel kits become a more cost-effective renewable energy source and help the planet, learning about average peak sun hours (otherwise known as peak sunlight hours) in your state will be beneficial to your solar installation.
What Is an Average Peak Sun Hour?
Scientifically speaking, a peak sun hour is when the sun’s intensity or solar radiation hits an average of 1,000 watts of energy per square meter for at least one hour. Usually, this happens when the sun is highest in the sky but can occur any time during the day. You can kind of think of average peak sun hours as the times of the day when laying out in the sun is more likely to give you sunburn because the sun’s intensity is much greater.
The number of peak sun hours in an area is essential to know when deciding about
solar panel installation. This measurement is what scientists use in labs when testing and rating solar panels output. So if a solar panel states it produces 300 watts, the assumption is that amount is possible during peak sun hours.
How Peak Sun Hours Are Used to Measure Sunlight?
Naturally, every location on Earth receives a different intensity of sunlight and hours of daylight, which also vary throughout the calendar year (thanks to the Earth revolving around the sun). But how do the hours of sunlight a place receives translate into average peak sun hours?
The math surrounding this calculation is pretty straightforward. If we measure an average peak sun hour equaling 1,000 watts of energy per square meter, or 1000 W/m², as our baseline, anything above or below this amount is proportional.
For example, if a specific location receives only 500 W/m² of sunlight for an hour in the morning, it would count as 0.5 peak sun hours. If it is a clear, sunny day, and that exact location then receives 1,500 W/m² for an hour in the early afternoon, it would come in at 1.5 peak sun hours. If the area gets 5,550 W/m² of sunlight during the day, its average peak sun hours would be 5.55.
Having this information on hand is very useful when determining which home solar panel kits best suit your location’s needs. Also, suppose you plan on using RV solar panels as you move around the country. In that case, you’ll want to familiarize yourself with each location’s average peak sun hours before arriving so you can plan accordingly.
Average Peak Sun Hours by State
Each of the 50 states receives an average of peak sun hours based on calculations throughout the year. Keep in mind that daily weather patterns can affect a location’s average peak sun hours, as can the time of year. This factor is particularly important for those using small solar panel kits that may not generate as much solar power.
Due to the size of many states, please note hours may also vary by region within a state.
Why Do Average Peak Sun Hours Vary by State and Location?
Let’s go back to science class for a little bit and learn why average peak sun hours can range anywhere from 2 to 7.5 in the United States. Yes, the U.S. is a huge country that goes from coast to coast with many climate zones, and this is part of why we see such variation in the state-by-state table. The closer a state or region is to the equator, the more direct sunlight it will receive.
That doesn’t necessarily mean a state like Alaska doesn’t receive as much sunlight throughout the year as somewhere like Florida. What it means is that Alaska won’t receive as much direct sunlight or reach that coveted 1000 W/m² per hour needed to count as a peak sun hour.
Another major factor in average peak sun hours is the weather a place experiences regularly. For example, states in the southwest like Arizona and New Mexico don’t experience many rainy days, allowing the sun to shine brightly for longer periods. Other regions in the US, like the northwest, receive a fair amount of cloud cover throughout the year, affecting their average peak sun hours.
Finally, some states not only cover more area than others, but they also cover more lines of latitude or degrees of distance from the equator. A state like California spans about ten degrees of latitude, while Tennessee only has approximately 1.5 degrees of latitude. That indicates that California will experience a vaster range of average peak sun hours than Tennessee (and variation due to other factors already mentioned).
What Are the Ideal Peak Sun Hours for Solar Panels?
Because we use average peak sun hours to measure solar energy production, purchasing the right-sized solar panels for your home’s location will go a long way in getting the energy output you desire. For states that receive higher average peak sun hours, fewer panels may be possible. More panels or battery chargers may be a better option for regions with lower average peak sun hours.
In general, anywhere with at least four average peak sun hours will benefit from solar panel systems. However, this doesn’t mean that solar energy isn’t an option if you live in a state with less than four average peak sun hours.
It’s important to factor in your home’s electricity rates and if your area is eligible for federal- or state-level tax incentives. In the case of federal tax incentives, going solar will save you 26% of the cost of installation (parts and labor). This credit can help you quickly offset the upfront cost and break even sooner than expected.
Additionally, if you live in an area with net metering where the electric company purchases the additional solar energy your panels produce, having low average peak sun hours may not be as detrimental as you may think.
How Can I Calculate the Peak Sun Hours for My Roof?
In addition to what state you live in, your home’s exact location, and any incentives offered in your area. You’ll also need to factor in the shape and size of your roof. Some roofs have a lot of square footage to play around with, allowing the homeowner to choose where to place their solar panels selectively.
Other roofs are more limited in size or have areas that would be off-limits to solar panels for various reasons, such as shading from trees or housing association regulations. Plus, you have to consider your roof’s angle, as this will affect how much sunlight it receives and at what intensity.
Lastly, your roof’s material plays a role in installing solar panels. Installation processes can vary depending on if your home’s roof uses shingles, tiles, metal, or other materials. Ultimately, solar companies should be willing to work with you and help determine the best course of action to get solar panels installed properly on whatever rooftop you have.
If you’re looking at doing some DIY solar work, you’ll need to measure your roof’s area, as well as its azimuth and tilt, to get an average monthly solar radiation estimate.
Calculating Your Home’s Total Watt Usage
Suppose you’re really interested in knowing how much your home’s average peak sun hours are related to how much electricity your home uses. In that case, you can use the Renogy Solar Calculator. To make the most of the calculator, you’ll want first to create a list of all the appliances and electronics in your home. You’ll need to note the wattage of each device on your list and estimate how many hours you use it each day.
For instance, if you have an LCD television that is 100 watts, let’s estimate that it’s on for four hours per day. That would mean your TV requires 400 watts of power per day or an average of 12,000 watts (12 kWh) per month.
If going around your house and doing this exercise with all your appliances and devices seems like too much of a chore, you have another option. You can reference the information on your monthly electricity bills.
The difficulty with using your electric bill is that it measures usage in kilowatt-hours (kWh), not watt-hours. The best approach to modify this and determine your watt-hour usage is to take your monthly kilowatt-hours and multiply them by 1,000. Now you more or less have how many watt-hours your home uses every month.
As an example, each month, the average American home utilizes around 875 kWh of electricity. If you multiply 875 by 1,000, you get 875,000 watt-hours for the month or about 29,000 watt-hours per day (which equates to 29 kWh).
If all of this seems like it’s a bit complicated, you can always give your utility company a call to get further assistance in reading your bill and getting the data you need for the solar cost calculator.
To Sun Things Up
These days, going solar isn’t just for those living in year-round sunny climates. It’s for anyone and everyone looking to transition to renewable energy sources that will create long-term savings while helping protect the environment. Regardless of which state you live in, installing solar panels on your home can help you generate and potentially store electricity.
To get the most out of solar panel installation, take the time to discover the average peak sun hours of your home’s location, and use a solar calculator to determine your home’s energy usage. Doing all of this work early on in the process will go a long way in discovering which solar panel setup will work best for your circumstances.
We also encourage you to look into any tax incentives or rebates available in your area. Once you have this information in hand, you can add it to your expenses and get a real sense of how long it will take for you to offset your solar panel installation cost. For the average American home, solar panels will have paid for themselves in about seven years. You can get this number down even further by taking advantage of incentives and rebates and making the most of your home’s average peak sun hours.
It may all feel somewhat overwhelming at times, but becoming familiar with terms like average peak sun hours will go a long way during your solar energy journey, and the more informed you are about the process, the more you’ll be able to get out of it!
See other related articles at Renogy：
Solar Panels 101: A Beginner's Guide
The Ultimate Guide To DIY Off-Grid Solar Systems
Do solar panels increase home value
how efficient are solar panels
How Many Solar Panels Do I Need
