How many sunlight hours do I need? Calculating peak sun hours

how many sunlight hours do solar panels need

When weighing the decision of whether or not going solar makes sense for your roof or location, one of the first questions you may ask is “how many sunlight hours do I need for solar to be worth it?” The reason this question is important is because there is a significant range across the country for average peak sun hours. In this article, we’ll explain which states offer the best sun hour value and how much sunlight intensity in your state should impact your decision to go solar.

What is a sunlight hour?

The first clarification to make with the term “sunlight hour” is that it does not refer to merely hours of daylight. While many areas of the U.S. will have practically the same total daylight, some states may only average two peak sun-hours per day while others will average as many as seven.

A peak sun-hour is typically defined as an hour of sunlight that offers 1,000 watts of photovoltaic power per square meter. Peak sunlight hours describe the intensity of sunlight in a specific area. Peak sun-hours occur when the sun is highest in the sky. The number of peak sun hours will increase the closer an area is to the equator and, more generally, during summer months.

What are the average peak sunlight hours in my state?

As mentioned above, U.S. homeowners will see major disparity in available sunlight depending on where they live. Check out how the top states for solar power stack up in terms of average peak sunlight hours per day:

Table: Average sun hours by state

State Average peak sunlight hours
 Arizona  6.50
 California  5.82
 Colorado  5.37
 Florida  5.44
 Massachusetts  4.0
 Maryland  4.47
 New Jersey  4.21
 Nevada 6.20 
 New York  3.58
North Carolina 5.01
 Pennsylvania  3.60
 Texas  5.64
 Virginia  4.13
 Washington  4.38

Source: Solardirect 

There are conflicting takeaways from this table: though many top states for solar in the U.S. have higher average sun-hour values (Arizona, California), other top solar states are on the lower end for peak sun-hour averages (New York, Massachusetts). Conventional wisdom would say that the states with the highest sunlight hour averages are the best ones for solar. However, number of peak sunlight hours is not the only factor that influences the cost-benefit ratio of solar energy.

For example, in states like Massachusetts and New York, sunshine is less plentiful. Nevertheless,  electricity prices in those states are high and there are a number of major states incentives that make solar affordable. The cost of energy can be more of a deciding factor for the economics of solar than available sunlight – hence why a state like Massachusetts is a much more popular place for solar energy than many of the sunny Southeastern states where the cost of energy is low.

Furthermore, in the case of states with high electricity prices but low peak sunlight hours, solar-interested homeowners can install higher-efficiency panels that will generate more power from less sunlight. Solar panel efficiency typically ranges from 15 to 18 percent, but premium solar panels like SunPower can offer efficiency levels as high as 22 percent. In a state with strong peak sunlight, an economy panel with lower efficiency will likely do the trick. By comparison, states with fewer peak sunlight hours can be just as ideal for solar panels, but will require more efficient solar equipment. For the prospective homeowner considering solar, the next step is to review our:

Three Tips for Solar Shoppers

  1. Homeowners who get multiple quotes save 10% or more

    As with any big ticket purchase, shopping for a solar panel installation takes a lot of research and consideration, including a thorough review of the companies in your area. A recent report by the U.S. Department of Energy’s National Renewable Energy Laboratory (NREL) recommended that consumers compare as many solar options as possible to avoid paying inflated prices offered by the large installers in the solar industry.

    To find the smaller contractors that typically offer lower prices, you’ll need to use an installer network like EnergySage. You can receive free quotes from vetted installers local to you when you register your property on our Solar Marketplace – homeowners who get 3 or more quotes can expect to save $2,000 or more on their solar panel installation.

  2. The biggest installers typically don’t offer the best price

    The bigger isn’t always better mantra is one of the main reasons we strongly encourage homeowners to consider all of their solar options, not just the brands large enough to pay for the most advertising. A recent report by the U.S. government found that large installers are $2,000 to $5,000 more expensive than small solar companies. If you have offers from some of the big installers in solar, make sure you compare those bids with quotes from local installers to ensure you don’t overpay for solar.

  3. Comparing all your equipment options is just as important

    National-scale installers don’t just offer higher prices – they also tend to have fewer solar equipment options, which can have a significant impact on your system’s electricity production. By collecting a diverse array of solar bids, you can compare costs and savings based on the different equipment packages available to you.

    There are multiple variables to consider when seeking out the best solar panels on the market. While certain panels will have higher efficiency ratings than others, investing in top-of-the-line solar equipment doesn’t always result in higher savings. The only way to find the “sweet spot” for your property is to evaluate quotes with varying equipment and financing offers.

For any homeowner in the early stage of shopping for solar that would just like a ballpark estimate for an installation, try our Solar Calculator that offers up front cost and long term savings estimates based on your location and roof type. For those looking to get quotes from local contractors today, check out our quote comparison platform.





Don



One thought on “How many sunlight hours do I need? Calculating peak sun hours

  1. Omar alghali

    It is very true that the big installers don’t offer the best price. But you get the structure, the longevity of the company incase of future maintenance, and you get more warranties on a product and labor. Both have pros and cons.

    Reply

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