Rooftop solar panels are enjoying their moment in the sun. Thanks to more efficient technology, increased availability, better infrastructure, and a suite of enticing federal and state incentives, the case for homeowners to install the glittering, energy-harnessing arrays and say “goodbye” to life on the traditional grid is stronger than it’s ever been.
According to the Solar Energy Industries Association, residential solar installations continue to set annual records. Currently, 7% of homes in the United States are powered via solar, and that number is set to hit 15% by 2030.1 And this is just the beginning. “We’ve only tapped 1/28th of our rooftop solar potential,” says Johanna Neumann, Senior Director of Environment America’s Campaign for 100% Renewable Energy and a solar panel system owner herself. “America could produce the equivalent of 45% of the electricity we currently use from rooftop solar, yet, in 2022, rooftop solar provided only 1.5% of America’s electricity.”2
Then there’s the environmental picture: Homes that run on sunlight cut down on greenhouse gas emissions, because they lessen dependence on the existing U.S. power supply—which is mostly sourced from fossil fuels like natural gas. Getting even half of a home’s annual draw (that’s around 5,000 kilowatt hours) from solar, is equivalent to leaving your gas-powered car parked more than half the time.3 “The most important environmental benefit of installing a rooftop solar system is that it allows you to run your home on renewable energy rather than fossil fuels,”Neumann adds.
It’s easy to see numbers like that and become immediately hyped to tile your roof with suncatchers. But rooftop solar isn’t right for every home, and it’s not (yet) a plug-and-play scenario. Going solar can also be a big investment, which means for a lot of homeowners it can be more of a financial decision than anything else.
So, if you’re considering a set of panels on your home, what should you know about the technology, installation, and costs? Let’s shine some light on it.
How do you know if solar panels are right for your home?
Whether or not solar makes sense for your roof all depends on its size and structure and such factors as the direction it faces and how much daily sunlight it receives. According to the Department of Energy, rooftop solar panels work best on south-facing roofs with a slope between 15 and 40 degrees.
There are several free online tools available to help you figure out if your roof can support solar panels. One of the most popular is Google’s Project Sunroof. Type in your address and, through a mix of machine learning and Google Earth imagery, the program calculates how much usable sunlight your roof receives per year, how much available space you have for solar panels, the recommended solar panel size you’d need to match your current electricity output, and the money you’d potentially save by having a system for 20 years. Energy Star’s Renewable Ready Energy Home Tool and the National Renewable Energy Laboratory’s PVWatts Calculator are also good resources.
Even if your roof’s structural specs aren’t perfect, all’s not lost. “The great thing is that solar panels are adaptable to various roof types,” says Spencer Fields, Director of Insights for the solar energy comparison resource EnergySage. “For instance, a flat roof will require extra racking equipment to ensure the panels are positioned at the ideal angle and direction. That comes with an additional cost.”
The condition of your roof is also a factor. Standard residential rooftop solar panels are 66 x 40 inches and weigh around 42 pounds. A roofer should evaluate your roof’s condition and an installation company should also have a structural engineer do the same to make sure it’s able to support the system. Both may offer recommendations for necessary repairs and reinforcements. While roof renovations can happen after panels are installed, it’s more costly as it requires removing the panels first.
How much money can rooftop solar save you?
For many, the most attractive benefit of switching to solar energy is the potential savings on their electric bills. According to Fields, the amount saved by switching to rooftop solar depends on three key things: how much electricity costs in an area, how much a solar system will run you, and whether or not you can connect your array to the grid and take advantage of a net-metering deal with your utility.
The average home in the United States consumes more than 10,000 kWh of energy per year. If you have a rooftop solar system that can produce that much every month, that translates to an average annual savings of $1,788 based on current rates. That amount is likely more if you live in an area where electricity is pricey or where utilities use surge pricing to counterbalance a strained grid. “Over a 25-year period, homeowners can expect to save anywhere from $20,000 to $90,000 with solar, influenced by factors such as electricity rates and system costs,” says Fields.
The financial payback period—that is, the amount of time it takes for someone to recoup their initial investment in a rooftop solar system—depends on variables like rising electricity costs and falling solar prices. But, on average, Fields notes that this takes around eight years. “Beyond this timeframe,” he says, “the electricity generated by the panels essentially becomes cost-free.”
Additionally, 38 states currently offer what’s known as net-metering programs for grid-connected rooftop solar. Since solar panels may capture more energy than a home needs or can store, the homeowner can opt to send those excess electrons back to the grid via utility companies. Through these programs, utilities compensate customers for that additional power in the form of a credit on their electricity bill or even a direct payment.
Net-metering, per Fields, is the foundational policy that makes solar work. “It allows you to send excess solar production to the grid when you don’t need it in exchange for credit for when you do need electricity,” he says. Many states, however, are reducing the value of net metering, which in turn extends the payback period for solar. It’s important to understand the policies in your area.
How much do rooftop solar panels cost?
While solar panels can save homeowners money long term, they’re quite expensive to install. There’s the price of the equipment itself as well as the cost of labor, permits, battery storage, and more. Depending on your needs and where you live, the total price could be anywhere from $15,000 to $40,000.
Are there tax incentives available for rooftop solar?
There are quite a few incentives available for solar panels. The Residential Clean Energy Credit offers a 30% credit to those who install solar panels on their home. It lasts through 2032; the credit drops to 26% in 2033. In addition, Neumann notes that if the panels are manufactured in the United States, you can save an additional 10%, and that many states also offer low or zero interest financing for solar systems. Your state may also offer additional incentives. These could range from tax credits and sales tax exemptions to low-interest loans and net-metering policies. The Database of State Incentives for Renewables & Efficiency offers a list of options.
Now, if these incentives are sweet enough to convince you to install solar panels, Neumann notes that many solar installers also offer power purchase agreements. Basically, they’ll own your panels and sell the power to you at a fixed rate which, she notes, is generally lower than the cost of power from the utility.
What should you know when shopping for solar?
After cost, probably the top consideration when weighing solar is where you’re going to get your panels and who’s going to install them. Often, these two to-dos go hand-in-hand, because a good installer will take care of a lot of the math, parts shopping, and paperwork for you. Even so, here’s what you should brush up on to follow what they’re talking about:
What are the key components of a solar system, and how long do they last?
Rooftop solar works by harnessing energy from sunlight and converting it into usable electricity. There are several components to a complete rooftop solar system, but the two biggest ones to understand are the panels themselves and a device called an inverter. Solar panels are photovoltaic cells that are most commonly made from a silicone semiconductor material. When sunlight hits the cells, photons are absorbed, their electrons are dislodged by the semiconductor material’s magnetic field. These electrons bounce around, creating a direct electric current which is then passed through a solar inverter. The inverter changes it into an alternating current, which is what your home runs on.
While there are several kinds of residential solar panels, the most common fall into two categories: monocrystalline and polycrystalline.
- Monocrystalline panels are made from a single piece of silicon. These are the most efficient—and expensive—options available. These panels have dark cells and operate at 15-20% efficiency, according to the American Solar Energy Society (ASES), which means that 15-20% of the sunlight that touches them is converted to energy.
- Polycrystalline panels are blue in color and made from multiple pieces of silicon layered together. They’re less expensive but also less efficient, with ASES noting they have an efficiency rate of 13-16%. Each polycrystalline panel produces between 250-300 watts of electricity and, like mono panels, should last 25 to 30 years.
Where can you find a good solar installer—and the right panels?
There are several options here. You can purchase solar panel systems through a licensed solar installer in your area, find panels and equipment at a store like Home Depot, which also has licensed installers, or buy directly from the manufacturer.
An installer is as close to a one-stop shop as you’re going to get. When shopping for a solar installer, it’s crucial that you do your research. Compare such factors as cost and warranties as well as estimated panel energy production, efficiency ratings, and performance. This tool from the North American Board of Certified Energy Practitioners lets you search your area for certified professionals. There are also many online comparison tools like EnergySage that funnel quotes from local companies and send them to your inbox for you to compare.
Whatever you do, be diligent in your research, as bad actors are lurking within the solar industry. For instance, TIME Magazine lays out a stark warning about how certain areas of the industry are still hobbled by a lack of regulation. It details such problems as setups not providing energy and discusses cases where companies who leased solar panels went out of business, hanging owners out to dry.
How many solar panels does your home need?
A qualified installer will work with you to determine the right number of panels for your home. According to Fields, the number of panels needed to fully power a home in the U.S. typically ranges from 17 to 25, assuming average energy consumption.
“The number of solar panels a home requires depends on how energy intensive that home is,” adds Neumann. “A home that is aggressive with energy conservation and efficiency measures will need fewer panels than one where energy waste runs rampant. Likewise, a home with all-electric appliances and an electric vehicle, will need more solar panels to meet that household’s energy needs than one that doesn’t.”
In most states, Neumann adds, home solar systems are only allowed to be sized to meet that household’s electricity needs, not exceed them. “So, if you’re planning to electrify appliances or get an electric vehicle, you’ll want to let your solar installer know that so they can size the system for your projected needs,” she says.
Do you also want a home battery backup system?
Solar panels free you from reliance on utility companies. But since cloud cover, inclement weather, and other factors can affect an array’s performance, most homes remain connected to the grid so they can still draw power when necessary.
Solar systems with battery backups are less reliant on the grid, but they’re not a must-have. These units, which are most often wall mounted, act like less-noisy generators and store excess energy owners can tap during evenings or power outages. As is the case with solar technology in general, batteries do come at a high upfront cost. Many consider them a luxury since it can often be cheaper to pay for energy from the utility company during outages. Here’s our guide to figuring out if this add-on makes sense for you.
What permits or documentation do you need to install solar?
A reputable installer will likely handle the gathering of the paperwork you need to install rooftop solar. While it varies from state to state and is dependent on such factors as the size of an array, the documentation you’ll need to install solar often includes a solar permit, building permit, and an interconnection agreement, the latter of which notifies your local utility company that you are installing solar panels and connecting them to their grid.
What does the installation process look like?
When you’re ready to move forward with the installation of a solar system, it’s important to understand the process and timeline. “The entire process may take a few months, with the actual solar panel installation taking about one to three days to complete,” he says. The installation process itself typically follows these steps:
- An engineering site visit
- Obtaining of permits and documents
- Ordering equipment
- Installation
- Approval and interconnection from your local government and utility company
What maintenance do solar panels need?
All things considered, a rooftop solar array shouldn’t need much attention. Solar panels need to be cleaned a few times a year to remove dust, pollen, bird droppings, and anything else that may accumulate on them, block cells, and lower energy production. This can be done by aiming a leaf blower at the panels to loosen any particles or debris before spraying them with a hose and wiping them down with a soft cloth. Ideally, the system should be cleaned by a professional. Owners can sign up for maintenance plans with their company, which, much like HVAC checkups, include cleaning as well as pest and systems checks.
Are there downsides to getting a rooftop solar system?
As with anything, there can be tradeoffs when considering going solar. Factors like weather can impact performance—plus it’s important to remember that even renewable energy systems come with environmental impacts.
Does temperature affect solar panels?
Most solar panels are rated to withstand a temperature range of -40 to 185 degrees Fahrenheit. Optimal performance, however, sits somewhere around 77 degrees. Photovoltaic cells start to lose efficiency in higher temperatures. For every degree above 77 degrees, a panel’s production drops slightly. Solar panels run better during cooler weather because lower temperatures improve cell efficiency.
And what about cloud cover?
While solar panels operate all year long, anything that obstructs the sun negatively influences a panel’s performance, including shade, cloud cover, and atmospheric conditions such as dust and pollutants. On days with low visibility, solar panels may yield only 10-25% of their sunny-day output. And, as they’re sun-dependent, solar panels don’t generate any electricity at night.
Do solar panels have negative environmental impacts?
Yes, there are certain environmental concerns about the manufacturing and production of solar cells. There’s the extraction of raw materials such as silicone and aluminum, which requires resources and may affect habitats. Then there’s the production of the panels themselves, each step of which requires natural resources and contributes greenhouse gasses. However, according to the NREL, the “energy payback” period—that is the amount of time it takes to offset the resources required to make the panels—is met after roughly three years of solar use.4
- Solar Market Insight Report 2023 Year in Review, Solar Energy Industries Association ↩︎
- Rooftop Solar on the Rise, Environment America Research & Policy Center and Frontier Group, Feb. 2024 ↩︎
- Greenhouse Gas Equivalencies Calculator, United States Environmental Protection Agency, Jan. 2024 ↩︎
- PV FAQs, U.S. Department of Energy, Jan. 2024 ↩︎