What Impacts Solar Panel Performance
Solar panels can vary quite a bit in their overall performance and productivity. There are a number of specific factors that can impact how your residential solar system performs, including:
- Orientation: When your home solar system is designed, your installer will be careful to position each panel in a way that maximizes its exposure to sunlight. If the orientation is even a little bit off, it can compromise the efficiency of your entire system.
- Weather and sun exposure: If you live in a part of the country that doesnt get consistent sunlight, or if your solar panels are often under cloud coverage, youre not going to produce as much clean energy for your home.
- Cleanliness: While solar panels are fairly low maintenance, you may occasionally need to wipe them down, especially in the aftermath of an intense storm or during a season like spring or fall when there is pollen or falling leaves that can block your panels. If panels become covered with grime or debris, they may not be able to absorb as much sunlight.
- Shade: Keep in mind that any shade cast over your roof is going to impact the efficiency of your solar panels. If your house is surrounded by tall trees, for example, that could impede solar production.
The Number Of Solar Panels You Need Depends Upon You
You now have a rough idea of the number of solar panels you need to power your home. Great! But still you have to pay attention to a few more details to set up your solar power system for success, including your budget and solar goals. We recommend you engage a solar panel professional to address the following questions about solar panel installations.
Googles Project Sunroof Helps You Find Out Whether Solar Is A Good Option For You & Work Out Potential Savings
Google has always been on the front lines of cutting-edge technology and the companys Project Sunroof is no different. The platform works similarly to the Sun Number Score and takes a few extra factors into account.
First, the website utilizes machine learning technology, 3D modeling, Google Earth, and Google Maps to determine how much sunlight your roof gets during a year. Additionally, Project Sunroof will also take into account the solar energy and electricity prices in your area.
It will also check if there are any incentives and rebates that your state provides in exchange for installing a solar power system. Finally, it will calculate how much money you can save by going solar, over a period of 20 years.
Since its launch in 2015, Project Sunroof has analyzed over 60 million roofs with some incredible results. Namely, Google has discovered that, in some states, up to 92% of homeowners could save money by going solar.
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Factors That Influence Solar Production & The Number Of Solar Panels Needed
As mentioned previously, there are several factors that influence how much solar energy your rooftop solar array will actually produce. These factors, in turn, partly determine the number of solar panels you need.
Ultimately, its your roof size which will dictate what the final result will look like.
The United States Environmental Protection Agency developed a helpful document titled Solar Photovoltaic Specification, Checklist, and Guide. It discusses many of the factors that influence solar energy production.
Here are some of the pertinent points from that Guide you need to take into account to maximize the success of your home or commercial solar project:
- Assume 500 sq. ft. for a 5 kW array . If using energy-efficient appliances, a smaller area will suffice.
- Roofs situated directly south receive the most direct sun. This is the best orientation. If the roof is more than 45 degrees off from due south, energy production will be very diminished. You should consider a ground mount system instead.
- The tilt angle of the array should match the arrays geographic latitude in degrees. Other sources adjust this value slightly. This is referred to as the inclination of the solar array.
- Conduct a solar shading study using a sun path tool such as Solar Pathfinder or Solmetric SunEye to determine the impact of shading on energy production.
Few Things About Solar Panel Output Efficiency
Solar panel type and quality make a significant difference in terms of solar output and efficiency. Not all solar panels are the same.
The amount of power your solar energy system can produce depends on the number of solar panels and efficiency with which they convert solar energy into electricity.
Why does efficiency matter? This number informs you about the ability of a solar panel to convert sunlight into energy. Standard solar panels have efficiency around 18 percent, but the span of most marketed products lies between 15 to 22 percent.
If you have a solar panel with 20 percent efficiency and one with 15 percent right next to each other under the same conditions, the more efficient one will produce more energy over the same period of time.
When determining how many solar panels you need, you have an option to reduce the number of panels by simply purchasing higher efficiency panels. This option may be a good option if you have limited roof space.
For instance, monocrystalline photovoltaic solar panels are known to be the most efficient solar panels on the market, but also the most expensive.
Their two main advantages over the less efficient types of solar panels is that 1) they absorb more sunlight and their output efficiency is not affected that much by temperature and 2) they occupy less space. These are an ideal option if you do not have enough roof space for more panels.
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American Vs Foreign Made Panels
The vast majority of solar modules are made in Southeast Asia. This makes sense because China is the largest installer of solar in the world, having about triple the installed solar capacity of the United States, and is continuing to install solar at a breakneck pace.
There are fewer choices if you want an American made panel, but it is certainly possible to find one. The problem is that it isnât easy for a consumer to find out where their panel is made, because itâs not usually listed on the product sheet.
Also, you canât tell where a panel is made simply by checking where the company is headquartered. Just like how a Chevy Blazer is made in Mexico while a Toyota Highlander is made in Indiana, youâll often find Chinese companies making panels in the US, and American companies operating factories in Southeast Asia.
For example, JinkoSolar is a Chinese company that operates a factory in Jacksonville, Florida, where they make their 72-cell mono-PERC module.
SunPower is a US-based company, but they no longer have any manufacturing facilities in the United States.
Mission Solar is notable because its a company that is headquartered and builds its modules in San Antonio, Texas. Another is Tesla, which is starting to manufacture its solar roof product in Buffalo, New York.
To learn more, read our article on made-in-America solar panels.
Where Can I Find My Homes Sun Number
Sun Number partnered with the real estate company Zillow in 2016 to enable homeowners and homebuyers to view sun numbers by simply entering the address at Zillow.com. Now, many properties have the sun number in the Zillow listing, helping home shoppers to consider a propertys solar potential before making a purchase. There are many properties that still do not list the sun number, however.
For homebuyers who are serious about installing solar, it helps them easily determine if a property is well-suited for solar panels. Likewise, current homeowners can use this feature to learn the sun number of their home . If you cant see your propertys sun number on Zillow, learn how to assess the solar potential yourself.
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How Many Solar Panels Do I Need
- Team Nexamp
As more homes throughout the country consider installing solar panels, one question commonly asked is, how many solar panels do I need?. Well, it depends there are a few factors that go into determining how many solar panels you would need to power your home or business home energy usage, roof or property surface area, orientation of your roof and geographic location. In this piece, well break it down for you.
How much solar energy do I need?
When determining how much solar energy you need your homes average energy usage is the first thing to look at. According to the U.S. Energy Information Administration, in 2019, the average electricity consumption for a U.S. residential utility customer was 10,649 kWh. Thats an average of about 877 kWh per month. To understand your own usage, a good rule of thumb is to look back at your total energy consumption from the last twelve months on your utility bills. Most utility bills provide this information. Divide that number by 12 and you have a great estimate of what youll need your solar panels to generate each month.
Energy Star South Southern Climate Zone
The Southern Climate Zone has hot summers and mild winters. As such, the Energy Star Factors are as follows:
Factors for Energy STAR Ratings in the Southern Climate Zone
U Factor & SHGC Combinations for the Southern Climate Zone
- U Factor of less than or equal to 0.40 and an SHGC less than or equal to 0.25
- Air leakage ratings of 0.30 or less
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How Many Solar Panels Do I Need For Common Appliances
By reviewing the various kWh requirements for everyday household appliances and products, one thing is clear: certain add-ons will dramatically change monthly energy use and can have an outsized impact on the size of the solar panel system you should install. For example, pairing your electric vehicle with solar panels is a great way to reduce carbon emissions and improve energy efficiency however, it should be planned accordingly, considering it could potentially double the size of your PV system.
Though it is certainly possible to install a solar system and then have a solar installer add more panels later to accommodate increased energy needs, the most pragmatic option is to size your system as accurately as possible based on your expected purchasessuch as an electric vehicle, swimming pool or central air system. Asking yourself, how many solar panels will I need for my refrigerator, my hot tub, etc. is a great habit for any new solar homeowner.
Solar panel requirements for individual appliances
| Product |
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How Much Is Your Energy Bill
Knowing how much you pay for energy is the first step in evaluating whether your house is a good candidate for solar. The main question is, will it save you money? In some areas, electricity is very inexpensive. For most homeowners, the electricity bill is a dreaded monthly expense. The general rule is that solar makes the most financial sense for someone with a monthly electricity bill of at least $75. Why? Because going solar replaces utility energy with solar energy, and we want our customers to see a return on that investment by paying less for that energy. A utility bill of $75 is the threshold at which residential solar customers will see solar savings. There are several ways to go solar, depending on a customer’s needs and goals. SunPower offers zero-down lease, loan and cash purchase options each with different benefits. Ask your local solar expert about local and federal incentives and electricity policies where you live.
The overall idea is to pay less than you currently pay, lock in your electricity rate and save money by generating your own clean energy onsite.
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Whats The Condition Of Your Roof
If youre looking at solar for an existing home, consider when your roof might need to be replaced. If your roof is nearing the end of its life, talk to an installer, says Vikram Aggarwal, CEO and founder of EnergySage, which helps consumers compare solar installers. You may want to get your roof replaced first, or get the work done in conjunction with your solar installation.
Some solar installers now offer roof replacement with installation services, or they partner with roofing companies. At the very least, solar installers should be able to provide referrals for reputable roofers. Since solar panels generally last 25-30 years, youll want to time both jobs accordingly.If youre building, discuss a solar integration with your builder sooner than later.
What Are The Best Solar Panels In 2022
For those who wish to take advantage of solar power for home use, the first step is assembling their home solar systems. This system will generally include a battery storage device, an inverter/microinverter, and of course an array of solar panels.
Based on factors such as efficiency, durability, product warranty, price point and temperature coefficient, these are the best solar panels for home use:
- LG: Best Overall
- Mission Solar: Best Small Manufacturer
- REC Solar: Most Reliable
- Windy Nation: Best for Backup Power
As you can see, each of these solar panels excels in a certain area, and each one comes with its own pros and cons. Again, as you seek the best residential solar panels, its crucial to consider the specific needs of your home and your solar power system. To get connected with a solar panel installer in your area, follow the link below any of the solar panel brands.
Watch Below: If you are just beginning to explore the solar industry, you may want to spend a few minutes familiarizing yourself on how solar cells even work. In the below video, the TED team eloquently describes just that.
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You Need How Many Hours Of Sunlight For Solar Panels
In the best-case scenario, youll want your solar panels to receive about four or five hours of direct sunlight. Specifically, that sunlight should reach your panels between 10 am and 3 pm.
This is when the sun is in its highest position and the rays are the most direct. If there are sources of shading on your property that block the sun from your panels during those hours, you may want to see what you can do to decrease the shade before installing solar panels. Your installation company will be able to help identify these obstructions.
Available In Your State
The first and foremost consideration in determining which solar panel installation company is best for you is whether or not a companys service or product is available in your state. While some solar companies are available in all, or most of the 50 U.S. states, others are regional and may not be available wherever your home is.
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How Much Of Your Home Is Shaded During The Day
Contrary to popular belief, a small amount of roof shade doesnt mean that solar wont work for you. In an ideal world, your roof would be open to the sun for the entire day to maximize your electricity generation. However, if your solar installer designs a system with the right components, you can minimize the negative impacts of shading. Even if trimming back your trees isnt an option, solar can still be a good fit for your home. If you own a lot of land with ample sun exposure, you may also be a good candidate for a ground-mounted solar system.
Experts Choice: The 5 Best Solar Panels Overall
I asked an in-house group of solar industry experts to weigh the pros and cons of different solar panel brands, and choose which ones they would install on their own homes.
After comparing all of the major brands on the market, here are the top 5 solar brands the experts recommend in 2022.
Table 1. The 5 best solar panel brands in 2022 according to experts
| # |
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| The most efficient solar panels on the market |
The experts focused on three key criteria when making their judgement:
- The manufacturer’s financial position
- Brand reputation
- Value for money
They explained that since solar panels last so long, it is crucial that the brand will be around to honor any warranty claims over the 25-year lifespan of the panel.
Their choices are divided into two categories of solar panels: three are premium solar panels, and the other two are value solar panel brands.
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Does Solar Power Work In Cloudy Weather
Yes, solar power does continue to work even on cloudy days. Photovoltaic solar panels work to continuously collect sunlight every day, though they work best when they receive direct sunlight. You also can add a solar battery to your home system. These solar storage devices collect the excess energy that your system generates and stores it for later use. Solar battery storage comes in handy during power outages or brownouts.
Calculating Your Solar Array Size In Kilowatts
Finally, with the numbers you calculated above, you can figure out the solar array size you need in watts every month.
Solar array = Monthly electric usage /
For the example above: 1,125 kWh / = 7.5 kW
So, for the average household that wants 100% of its energy created by the sun, their rooftop solar array must be 7.5 kW in size.
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Energy Star Northern Climate Zone
The Northern Energy STAR Climate Zone recently underwent changes it its criteria of what constitutes a window that insulates well. This is covered in the U-Factor article, but it is worth mentioning because it also impacted the solar heat gain coefficient for the Northern Zone.
If you started shopping prior to January 1, 2016, then you might notice some of the windows you were considering buying no longer carry the Energy STAR sticker. Most manufacturers worked to retrofit products to meet the new and more stringent standards.
Though the original proposed changes to U-Factor and SHGC to Energy STAR would have cut the market share by 50% due to vastly increased costs of manufacturing that would have been passed on to the consumer. Fortunately, Energy STAR pulled back a bit, which means windows could remain a bit more affordable.
To remain as Energy Star products, manufacturers had to either make changes to their effected products or lose the rating altogether. The manufacturers may have improved the materials that made up the frames or the coatings to the glass to meet demands. Depending on how many changes a manufacturer had to make, it could have greatly impacted the retail price of your window replacement installation.
The other climate zones underwent more stringent Energy Star qualifications that took effect on January 1, 2015.
Factors for Energy STAR Ratings in the Northern Climate Zone
