Does it matter what size solar panel you have installed on your roof? And how do you figure out which panel is right for your home?
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The good news is, you don’t have to do it on your own. Partnering with a professional, experienced solar company is a major way to give you understanding and peace of mind. The right system, with the right panel size and wattage, will lead to savings and energy independence from your decision to go solar.
When searching for different solar panel sizes online, you may find panels are differentiated by their wattage, or by the number of cells on a panel, rather than their physical dimensions or arbitrary sizes like small, medium, and large.
A solar panel’s wattage, or power capacity, refers to its energy generation potential, with higher wattage panels able to deliver larger amounts of solar electricity. Solar panel wattage is abbreviated simply with a “W'' and 1,000W is equal to one kilowatt (kW). If you want to go into more math and the metric system, you can learn more about watts, kilowatts, kilowatt-hours.
While there are no standard sizes, most of today’s premium home solar panels come in one of three primary formats, classified by the number of solar cells.
High-quality residential solar installations in the US typically utilize solar panels rated between 250W and 430W. While lower-wattage solar panels (below 250W) may work for small, off-grid systems, higher-wattage solar panels are better suited for commercial or utility installations with fewer space restraints than residential rooftops.
Strung together and wired into your home’s electrical system, solar panel wattages are added together to calculate your total solar capacity. So if you install 20 solar panels, each rated at 325W, your total solar panel wattage would be 6,500W or 6.5 kW.
Half-cut solar cells are part of renewable energy tech innovation in , with several new products now available from solar panel manufacturers. Made up of solar cells that are “cut in half,” panels with this technology are the same size with double the number of cells. These panels increase power potential in the same installation footprints.
Half-cut panels typically contain 120 or 144 half-cut cells. As a new product, solar panels with half-cut cells may not be available in all markets and are usually more expensive than traditional 60 and 72-cell panels.
For efficient electricity production and ease of installation, nearly every home solar energy system is installed with the same panel wattage (and model) per panel throughout. Knowing this, calculating the dimensions of a solar panel array is fairly straightforward. Take the sum of the panels’ dimensions as they are arranged and installed on your roof.
To illustrate how much roof space is needed for solar panels, let’s say you decide to install a 9.6kW system to offset your home’s electricity use. This capacity can be created with 24 72-cell 400W solar panels, covering about 21 square feet each. In this scenario, you would need roughly 500 square feet of installation space (21 square feet x 24 panels) to host your system.
It’s usually possible to add solar panels to an existing system. It’s typically more straightforward and better economic sense to build the system you need at the outset.
If your circumstances change after installation, maybe you’re getting and charging an EV for the first time, maybe you’re electrifying your home, it’s likely you can expand your system. You’ll need to figure out if your system’s permitting, components, like the inverter, and your roof are compatible with more panels.
Another potential answer to maximizing your use of your solar electricity is adding solar battery storage.
Batteries store the unused electricity generated by your panels. You can use the power when needed, such as at night or during power outages. Instead of needing to add panels, you may be able to use your electricity more efficiently. Solar batteries can give you greater reliability, independence, safety, and savings.
Unless you are planning a DIY solar panel installation, more often than not, you will not have to worry about choosing the right solar panel size for your home. Instead, a professional solar installer can work with you to determine the best solar panel wattage and size for your roof or property, tailored specifically to your unique energy demand, electricity costs, and available installation space.
Palmetto experts are always available to answer your questions about home solar power and ways to save money. To learn more, contact a Palmetto Solar Advisor today or use our solar savings calculator.
How many solar panels do I need?
Palmetto will calculate how many solar panels you need based on your power usage, the goals you have for your solar usage, your potential savings, your roof dimensions, and more. We work with each customer to answer every question and design the specific solar system for your home.
Does the size of my solar panels matter?
Yes, the physical dimensions of your panels matter as they relate to the available space on your roof. Solar panel wattage helps you calculate the overall capacity you need for a system which meets your family’s needs.
What if solar panels don’t generate as much electricity as I need?
If your solar panels are connected to the grid and are not giving your home enough electricity, electricity from the utility company will make up the difference. If this is a problem, potential solutions include adding solar battery storage or adding panel capacity to your system.
What happens if I produce more power than I need?
Contact us to discuss your requirements of High Power Solar Panels. Our experienced sales team can help you identify the options that best suit your needs.
If your home is connected to the grid and you have net metering, excess energy produced can flow into the grid and earn you credit on your electricity bill. If you choose to integrate energy storage with your system, any excess energy not immediately used by your household will be stored in your battery.
The solar industry was shaken up over the last year, and it might have you confused.
The Inflation Reduction Act, providing a 30% tax credit for the cost of solar panel system installations, along with falling solar panel prices and rising electricity costs, makes the case for adding solar panels to your roof. Changes to net metering in California and elsewhere mean that the case for some people isn't as strong as it once was (though the argument for batteries might be stronger).
If you're trying to make sense of it all, start with our tips for calculating your savings, finding an installer, deciding if a battery is right for you and what ome improvements you might want to tackle before jumping to solar. Read on for all that and more.
Can solar panels save you money?
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Solar panels are made of photovoltaic cells, which convert sunlight into electricity. The sun emits solar radiation, which is absorbed by the photovoltaic cells. Electrons within the solar cell are energized, escape their bonds and form an electric current. That current, which starts as direct current, is switched to alternating by the solar system's inverter. From there, it's used up in the electronics in your home or sent back to the grid.
"It's not a magical technology, but it seems like it because you just stick something in sunlight and it makes electricity for you," said Joshua Pearce, a professor at Western University in Ontario and co-author of To Catch the Sun, a free e-book on DIY solar systems. "Even being a scientist who works on this stuff all the time, it's amazing that these things actually work."
Why would you want solar panels at home?
Many businesses specialize in selling and installing solar panels for homes. Search online to locate solar panel suppliers and installers in your area. You can start with CNET's best list of solar panel companies. You can even shop for solar panels at major home goods stores like Home Depot. Stores like this can set you up with professional installation to help you get a residential solar panel setup.
Major installers often offer solar financing options, too, though you might be best served by shopping around for a loan, especially with high interest rates. Many solar installers also offer solar panel leases or power purchase agreements, which you can enter with no money down (though savings over the lifetime of your panels are typically lower). You can also apply for the federal solar tax credit, which will give you up to 30% of the cost of your solar back to you on your taxes, assuming you have that much tax liability.
Most residential solar arrays are installed by a professional. Installing solar panels yourself is technically possible, but you run the risk of voiding warranties. You should only attempt it if you have the necessary expertise. If you opt for a professional installation, be sure to shop around for the best deal. Compare the warranties installers offer along with price, customer service and how well their proposed plans meet your needs.
A reputable solar installer will advise you on the age of your roof before installation. Replacing your roof before installation may ultimately be the cheaper option, since removing the panels to replace the roof will be an additional expense.
Many solar panels are warrantied to last 25 years, though their useful life is likely longer. On top of that, they're fairly maintenance-free, just requiring that you keep them free of obstructions like dirt, leaves and snow. More extensive repairs may be covered by warranty.
Solar panels become less efficient over time, though that downward trend is not necessarily a problem. A typical manufacturer's warranty will guarantee that your solar panels won't lose more than 2% efficiency in the first year and not more than 0.5% per year in the next 24 years. That means your panels are guaranteed to produce at 84% their original capacity after year 25. Some panels will set a higher benchmark — like 92% — after 25 years, but you'll still be getting plenty of electricity out of them two decades on.
Installing a solar battery in your home will allow you to store excess energy produced by your panels. However, they are currently almost as expensive as a solar panel system (from $12,000 to $22,000), so while a battery is nice to have, it's not a necessity.
There are instances where a solar battery is worth the investment. Those who live off the grid will need a battery to use solar power. And if your area is prone to frequent blackouts or you have medical needs that require refrigerated medicine or machinery, a battery may be worth the cost.
If net metering has been eliminated or weakened where you live, a battery might make solar a better proposition. Since you won't be compensated as much for the energy you send to the grid, storing more of it to use later can save you more money, despite increasing the initial cost of the system.
There is a variety of options for paying for the installation of residential solar panels, aided in part by the 30% federal tax credit. Homeowners can pay out of pocket for the entire project, then receive money back from the government. There are also plenty of solar loan options that also allow you to claim the tax credit. Interest rates have shifted higher over the last year or so, which means you should shop around for the terms that best fit your needs. Other financing options include bank loans or a home equity loan, but given their higher interest rates, consider these financial tools carefully.
For those without the financial means to buy or finance a system, there are solar leases and power purchase agreements. A solar lease is similar to that of a vehicle, where you pay a set amount each month for a system that will be owned by the installer. Under a power purchase agreement, you pay a set rate for the energy that is generated by the solar panels (the rate may increase after a certain amount of time), rather than the system itself. The drawback of these mechanisms is that you won't own the solar panels yourself, and hence won't get any of the tax credits or have the ability to sell renewable energy certificates.
The federal residential solar energy credit, which grants a 30% credit to homeowners who install panels on their home through . (If your entire project costs $30,000, you'll be granted a credit of $9,000). The credit applies to homeowners who purchase a system with cash or through financing. According to the Office of Energy Efficiency & Renewable Energy, you should seek professional tax advice to determine your eligibility, then fill out IRS Form following the instructions.
Before you start the process of going solar, you should try to improve your home's energy usage in other ways.
"Solar is an exciting type of infrastructure, but if the ultimate goal is to save money on your electricity bills, I encourage homeowners to think about efficiency upgrades first," said Gilbert Michaud, assistant professor at Loyola University Chicago's School of Environmental Sustainability. "Those could include insulation, upgrading and replacing windows or other things that are maybe less fun, but can help you realize savings immediately and lower costs. Once you've done those efficiency retrofits or upgrades, maybe solar is a good idea."
These upgrades will give you a clearer idea of how many solar panels you'd need to power your home, too. That means you'll likely need less panels — reducing the cost of the installation — than if you didn't do efficiency upgrades first. Here's some suggestions.
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