How Much Roof Space Is Needed For Home Solar Panels?
When it comes to residential solar panels, your home’s roof is the most obvious place to put them. But it’s easy to get confused about how much roof space is needed for solar panels in order to install a home solar power system. Not all roofs are constructed to the same size or specifications, and some homes have roofs with steeper pitches, while others have roofs with more faces or odd shapes.
We’d love to tell you a simple formula for the exact amount of square footage that is required for a certain number of panels, but it’s not quite that simple. Each residential solar panel array is custom designed to match the homeowner’s needs and the unique size, shape, and dimensions of their roof, so the square footage that’s needed is going to depend on a number of factors.
If you’re wondering, “How many solar panels will fit on my roof?” then here are a few things to consider.
How To Calculate The Solar Potential Of Your Roof
There are a few rules of thumb you can follow that can offer a general idea of how much roof space is needed for solar panel installation. These guidelines can also help determine how much roof space you have available to put solar panels on.
Generally, every square foot of roof space has the potential to generate about 15 watts of solar energy. Thus, a solar panel installation on a small home might only need around 200 square feet of roof space, while a larger home can require more than 1,000 square feet of roof space to properly offset electricity usage.
To offset an average amount of energy usage by the average American home, you’ll typically need around 18 to 24 panels to be effective. That is, of course, if everything about those panels is ideal, where the positioning is optimal, the panels are of a standard rating, and the location gets adequate sunlight year-round. If you change any of those variables, the number of panels you need is going to change as well.
If you want to get a sense of how many panels a roof can support, you don’t need a fancy solar panel square footage calculator. Here’s an easy calculation you can do: Multiply the square footage of your roof by.75 to account for the required solar setback. ( on that below.) Take that number, and divide it by 17.5, which is the average square footage of the standard solar panel size. The resulting number is the maximum number of solar panels you can fit on your home’s roof.
If you’re not sure of the square footage of your roof, there’s another relatively easy calculation you can do: First you need to know the dimensions of your roof from ground level. You can measure two sides of your roof from the ground, and then multiply those numbers together to get the square footage. If your roof isn’t flat, you need to account for the angle of your roof as well, so measure the angle from the ground (most smartphones have angle measurement apps that you can use) or just use 35 degrees to get a rough estimate if you don’t have an unusually steep or shallow roof. Then take the square footage that you measured from the ground and divide it by the cosine of your roof’s angle to get the total square footage. If you need a solar panel square footage calculator, you can click this link to get a sample calculation for a roof that measures 400 square feet from the ground, and has a 35 degree angle, and then just change those values to match the measurements that you take.
How Close Can Solar Panels Be To The Edge Of The Roof?
Most roof-mounted solar installations will need a “solar panel setback” for safety. This is one of the most common roof requirements for solar panels in local and state building codes. This setback is the open space between the edge of the solar array and the edge of the roof, and it provides an unobstructed pathway around your rooftop for emergency responders like firefighters to get better access to your home in case of an emergency.
The minimum solar panel setback varies from state to state, but generally, the setback will take up about 25 percent of your roof’s usable space. This accounts for two roughly 36-inch wide pathways that run along the edge of your roof, on a roof with just two basic faces. If your roof is more complicated than that, with multiple faces, or different shapes that come together at odd angles, your setback requirements may be different, which is why it’s important to work with solar professionals when designing your home solar power system. Palmetto’s team of solar designers not only make sure your roof space is optimized for power production but that it also meets the requirements of all jurisdictions as well.
Factors to Consider When Determining How Many Solar Panels You Need
When determining how many solar panels you need, it’s important to start by thinking about what your goals are and why you want to go solar in the first place. Do you want to maximize your return on investment? Do you want to save as much money as possible? Do you want to reduce your upfront costs? Do you want to have the biggest environmental impact and reduce your carbon footprint as much as possible? Most people want a balance of these goals, and may have other priorities as well, so it’s helpful to get a clear idea of what your specific end goals are before you start designing a solar power system.
Once you have your goals in mind, then you can determine how many solar panels you need to get there. This calculation is going to depend on how much energy your family uses, how much roof area you have available for solar panels, the location of your home and the angle of your roof, how much sunlight shines in your part of the country, the efficiency of the solar panels you’re using, and if your local utility offers net metering. Plus, you also need to consider your budget, because a large solar power system might produce more energy, but it’s going to cost more for the initial installation as well.
Here are a few things you should think about when determining how many solar panels you need for your roof.
Energy Usage
How many solar panels you’ll need, and thus how much roof area for solar panels you’ll need, starts with an estimate of how much power you use in a given year. There are plenty of ways to determine your annual energy usage, but the easiest is to simply take a look at your current monthly energy bill. It should tell you how many kilowatt-hours of energy you use in a given month, then just multiply that number by 12 to get an annual estimate. If you don’t know your own estimated energy usage, a good starting number is that the average American home uses about 11,000 kWh of energy every year.
You should also consider any potential changes to your family’s energy usage in the future that you might want to account for. For example, if you buy a new electric vehicle that you plan to charge at home, or if you start working from home more often, or if you expand your family with a new child, your energy needs might change pretty significantly from the previous year.
Location (How Much Sunlight You Get)
Different parts of the country get different amounts of sunlight. For instance, Arizona is famous for intensely sunny days. On average, Arizona gets 300 days of sunshine every year. Conversely, Juneau, Alaska, spends more than two-thirds of the year in darkness.
This impacts how much roof space is needed for solar panels, because depending on where you live, you’ll need more or fewer solar panels. So if you live somewhere with lots of sun, you might only need enough roof space for a few solar panels. But if you live in Juneau, you’ll need lots of solar panels on your roof to harness the available energy.
The direction of your roof also determines how many solar panels you need, as southern-facing roofs in the northern hemisphere are ideal, as they receive more direct sunlight and can use that sunlight to create more energy. If your roof does not face south, you may either need a more complicated installation to get your panels facing the right direction, or you may need more panels to make up for the difference in energy-creating potential.
Size and Rating of Your Solar Panels
Solar panels can vary in size and rating, leading to different sized systems for the same amount of energy output. Some panels might be smaller but have a higher watt rating, which means they’re more efficient than a larger panel with a lower rating. That’s why you must consider the efficiency of the panels when determining the total solar panel system size for your roof.
While the efficiency of solar panels might vary, solar panel sizes typically don’t, as most companies have a standard solar panel square footage to make installation easier. The standard solar panel size dimensions are about 65 inches by 39 inches, which is roughly 17.5 square feet.
Your Solar Budget
Generally, larger systems are a great way to quickly offset your current electrical and fossil fuel energy usage. However, larger systems are naturally more expensive. While you may have the roof real estate for a large array, you might not have the financial budget for it, and vice versa.
Another thing to consider when figuring out your budget is whether your local utility offers net metering, and what rate they offer for that net metering. If you’re not familiar, net metering is when your utility company offers you credits for the extra energy that your system produces and feeds back into the grid. These credits can then be used to offset the cost of power that you might need to draw back from the grid, such as at night or during storms if you don’t have a battery storage system. If your local utility offers a generous net metering policy, it may allow you to expand your initial budget and then make up that difference over time.
Is It Possible To Install Too Many Solar Panels?
Believe it or not, it’s not always beneficial to install as many solar panels as you can possibly fit on your roof. Adding extra panels that aren’t needed just increases the cost of your initial investment, and if you don’t have a way of capturing or getting credit for the extra energy that you’re generating but not using, then you’re not getting a good return on that investment.
A good solar installation should offset as close to the exact amount of energy that you use as possible. That’s why we typically ask for samples of previous power bills when designing a system. These power bills help us estimate your power requirements, and design a system that matches your specific needs. Some months you might use more energy than your system produces, and some months you might use less energy than you produce, but at the end of the year, the goal is to generate about the same amount of energy as you use.
That said, there are some instances where it makes sense to install more solar panels to generate more energy than you plan on using. The first is if you plan on installing an energy storage system to capture that excess energy. Solar battery storage lets you use the energy you generated during the day to power your home at night, and also gives you a backup source of power in case you have a blackout or other issue.
Another time that you might want to generate more power than you plan to use is if your utility offers a strong net metering benefit. Net metering is when the utility gives you credit for the extra electricity that your solar power system produces and then feeds back into the grid, and this can help offset the cost of any electricity that you pull from the utility when your system isn’t generating electricity, like nighttime or during large storms.
In general it’s not possible to install too many solar panels (as long as your roof has space for them) but there just might not be a significant advantage to doing so.
How To Put Solar Panels On Your Roof
Your home’s roof space is just one of the factors that determines the optimum solar power system for your family’s needs. The arrangement of panels and the difficulty of the installation is determined by your roof, but you also need to consider your family’s energy needs, any future changes that your family might expect, your local incentives and net-metering programs, and a variety of other factors. Fortunately, Palmetto can help figure out the precise number and type of panels that will work best for your roof, and make it easy to get a system that’s perfectly matched to your family’s needs.
To find out how many panels you can put on your roof, get started with a free solar estimate, and a Palmetto solar expert will help design a system that’s just the right size to meet your energy goals.
If you want a greener environment for your roofs, residential solar panels are definitely the one for you!
Solar Panels obtains direct energy from the Sun causing less pollution as it replaces fossil fuels. Putting up Solar Panels to your roof is a great way towards preventing climate change.
If you want to help change the world in your own little ways with a few costs that are worth a long time, consider a Solar Panel Installation now!
But before installing one, here are some Roof Requirements for Solar Panels you need to check:
Is Your Roof Ready To Support Solar Panels?
Do you know how old is your roof? When was the last time you had them repaired?
If your roof shows signs of cupping, lifting or other damages, make sure to have them repaired first before considering solar panels. You may inquire with our Roof Repair Services to know if your roof can already support the solar panels you need.
You may also check the warranty of your roof and the solar panel that you will get. If the warranty of your solar panel is about 10 years and the warranty of your roof is only about 5 years, you may want to consider finding a new roof to better support the solar panels needed to be installed.
Consider The Size Of Your Roof
Does your roof have enough space where the solar panels will be placed? An average size for a good space of the roof would be 400-600 square feet.
Usually, each solar panel takes about 18 square feet. The ideal roof for solar panels should be 30-40 degrees with a slanted style rather than a flat one.
Slanted roofs are the best option for solar panels but having flat roofs is just as fair. Ask a professional Solar Panel Installation on what works best for your roof!
Consider The Type Of Your Roof
Is your roof made out of shingles, clay, or slate? Make sure to inspect your roofs first before installing a solar panel.
Solar panels work best with shingles as they are the most popular and easiest type of roof that a solar panel can be attached to. Clay or slate roofs tend to break that’s why it is not advisable for solar panels to be put onto.
You really need to be extra careful when you have a clay or slate roof. Inquire for the help of a roof expert if you want to get your roof check for it to be compatible for solar panel installation.
Know Which Direction Your Roof Is Facing
If you want to get the quality amount of sunlight, you need to know where your roof is facing. You need to determine where to put the solar panels to get the best source of sunlight and have good placement for it.
Most professionals say that your roof should be facing the South with 180-195 degrees orientation to receive the most amount of sunlight for your panels. Learn more about how solar panels work to better understand its benefits.
Check If Your Roof Has A Clear Surrounding
Solar panels need to be exposed to the sun for a long time to recharge the energy that it has given off the past hours. It should get a continuous amount of sunlight for about 6 hours and more.
Obstructions such as chimneys, dormers, shadows from the trees, buildings, or neighbors whose house is taller than yours should be limited. If your solar panel does not have a clear path to get the right amount of sunlight, chances are the production of electricity is reduced.
Let your place get checked by a professional roof installation service. Know when is the best time to put up your solar panels and know if your roof is ready for a big change!
Determine The Strength Of Your Roof
Installing solar panels on your roof would mean increasing the weight that it should hold. If your roof is not sturdy enough to carry the weight of the solar panel that will be installed, chances are, it will collapse.
This will be dangerous for your family and it will cost you more expenses for roof and solar panel repairs. Not to mention the cost of an installation service for both.
If you don’t want to experience this painstaking situation to happen, have a professional roofing service to evaluate the needs of your roof before a solar panel installation.
Prepare Your Budget
Making the switch to clean and renewable energy takes a lot of money. A solar installation will cost you an average between 15,000 – 29,000.
You will be needing a big amount of money if you want to have a green alternative for your energy sources. It is a big investment but it will also help you reduce costs for a long time when you find the right solar panel installation services.
Installing solar panels would mean a perfect renewable energy source which helps improve the environment and public health. Make the right choices now and get bigger savings tomorrow!
If you want to more about solar panels roof requirements, hire the best solar panel installation services and call Hollister Roofing at (831)-636-0188 today!
Roof replacement with solar panels
Solar panel systems will typically last around 30 to 35 years – and in that time, your solar panels will generate plenty of savings on your electric bills! These systems have very long lives, which leaves many homeowners wondering about the impact they will have on their roofs: how will the roof hold up over time? What happens if you have to replace your roof after installing solar? Should you just replace your roof at the same time you install solar panels? In this article, we’ll explain what you need to know about replacing your roof when going solar.
Should you replace your roof before installing solar panels?
Before you install solar panels, consider requesting a roof inspection to make sure it can withstand installation, especially if the roof is towards the end of its life. If your roof is between five and 10 years from needing replacement, it’s a good idea to get an expert out there to assess.
Most solar companies don’t offer roofing services, although there are some exceptions. Either way, roof work is commonly performed alongside a solar installation and your solar contractor likely has good referrals for roofers in your area – they may even be able to get you a discount on your roof replacement.
If your installer determines that your roof should be replaced prior to going solar, it’s a Smart move to do so. Solar panels are more durable than most roofing materials – so, when you pair solar with a roofing installation, the panels actually extend the lifetime of the portion of the roof that they cover.
The other benefit of pairing solar and a roof replacement together is that if you’re installing on a new roof, it’s unlikely you’ll need to re-roof during the lifetime of the system. This can help save you money in the long run because you’ll avoid the costs associated with removing and reinstalling the solar panels on your roof.
How much does a roof replacement and solar panel installation cost?
In the case that you do need to replace your roof prior to installing solar panels, you’re likely wondering how much your solar panel installation will cost. The average cost to install a new solar system in 2022 is 20,000 before rebates and incentives (like the federal tax credit), based on EnergySage Marketplace data. The average cost to replace a roof is about 10,000, according to This Old House. Therefore, you can expect an average new solar system installation and roof replacement to cost about 30,000. However, you may be able to knock a significant amount off of that price if you opt to combine the two larger costs. You can save up to 30 percent off of your new solar system with the federal tax credit and may be able to receive discounts on the roofing costs if your local roofing contractors or solar installers have partnership agreements to offer customer discounts.
How much does it cost to remove solar panels to replace your roof?
If you run into a roofing issue and need to replace your roof post-installation, there will be labor costs associated with taking the panels off your roof and putting them back on. Unfortunately, it’s hard to give specifics on the costs associated with this labor, as it can vary greatly. Installers will have different rates for their labor and the cost can also vary based on the size of the system, how many panels will need to be removed, and whether you need a place to store the equipment.
If mounting hardware also needs to be removed in order to replace your roof, this will add onto the cost. On average, residential installations tend to cost somewhere between 1,500 to 6,000 to remove and reinstall. (This is not inclusive of the cost required to replace your actual roof.)
If re-roofing post-installation is a concern for you, it’s always good to ask your potential installer how often they do this type of work, and the typical cost associated with it. Some companies will actually specify a price for this in your initial contract, and it never hurts to request this from your company prior to installation.
Do solar installation warranties cover the roof?
Roofing issues caused during the installation process or overtime are uncommon, but many solar installation companies often have warranty coverage for your roof where the panels are located in case you need a roof repair. Many companies do this because it’s common for existing roofing warranties to become void if you’re installing solar, at least for the portion of the roof where your system is installed.
The typical duration of this type of warranty is 10 years, but it can vary from company to company. Before you sign a contract, confirm with your installation company whether they warranty the roof and the duration of that warranty.
Should you install a solar roof?
Solar shingles or building integrated photovoltaics (BIPV), like the technology offered by Certainteed or Tesla, are certainly more attractive if you have to re-roof. The solar tiles or shingles will replace the roofing material itself, so you won’t need to spend money on both and can still generate savings on electricity.
Is going solar still worth it if you need to replace your roof?
An average solar installation will save homeowners tens of thousands of dollars on utility bills over its lifetime while generating clean, renewable energy! Re-roofing costs can be high, but the savings of using solar power should make up for it in the long term, especially with rising energy costs – and there’s no better time to evaluate solar if you were planning on re-roofing anyway (those panels love new roofs!). Many homeowners find that they receive discounted rates from roofing companies that have existing partnerships with solar companies, and you could save as much as 30 percent on roofing costs if you replace your roof and install solar at the same time.
If you think that you might be moving in the future, you might be worried about putting money into a new roof and a solar system. But that shouldn’t be a concern: if you go solar at the same time as replacing your roof, you’ll also likely increase your home’s resale value. A new roof already improves the value of your home, and many homebuyers are looking for electric and environmentally friendly homes, making your solar system very attractive!
Start shopping for solar today
If there’s a potential solar installation on your horizon, try out our Solar Calculator to get an estimate of potential costs and savings, or use the EnergySage Marketplace to get competitive quotes for solar installations from local and certified installation companies specific to your home. If your roof is on the older end, you can note this in your account. EnergySage installers can give you advice on potential roofers to contact, or sometimes even do the work themselves.
reading on EnergySage
Looking to go solar? Here’s everything you need to know in… Are solar panels worth it in 2023? Best solar panels in 2023: Top products compared Solar shingles: what you need to know in 2023 How to install solar panels
Which Commercial Roofs Are Suitable for Solar Panels? 5 Design Tips
According to the Energy Information Administration. the US will add 21.5 gigawatts of solar power in 2022, representing 46% of the new capacity forecast. Solar power is now the fastest growing electricity source in the country, and the modular design of photovoltaic panels makes them viable at all project scales.
Commercial buildings with large roofs can take advantage of their space, installing solar panels to cut their power bills and emissions. These solar installations also benefit from economies of scale: according to data gathered by the Solar Energy Industries Association. a home solar system has an average price of 3.06/watt in the US, but this decreases to 1.45/watt in commercial systems.
Get a professional electrical design for your commercial solar PV system.
The first step before installing a commercial solar array is making sure you have an adequate roof. In the case of new commercial buildings, owners have the advantage of being able to design a solar-ready roof from the start. Here are five recommendations to optimize your commercial roof design for solar panels.
) Flat Commercial Roofs Are Ideal for Solar Power
A flat roof simplifies the installation of solar panels on a new commercial building. Since solar installers will not be working on a sloped surface, the process becomes safer and easier. You can also use a ballasted mounting system, which holds solar panels in place with concrete bases. In other words, you will not be drilling holes on your new roof, which is necessary when solar panels are installed on sloped surfaces. Once your commercial solar array is operating, a flat roof also makes maintenance simpler.
) The Roof Structural Design Should Consider the Solar PV Array
A 72-cell commercial solar panel can weigh over 60 lb, and large commercial arrays can have hundreds of them. According to the National Renewable Energy Laboratory (NREL), a PV system increases the load on a roof by up to 6 lb per sq.ft., when you consider racking systems and other components.
To design the roof properly, the structural engineer in charge of your project must know the load distribution of your solar array. Keep in mind that ballasted mounted systems are heavier, since they use concrete weights to hold solar panels in place.
) Optimize the Orientation of Solar Panels and Avoid Shading
Since the sun’s position in the sky is always changing, the angle from which solar panels receive sunlight also varies. Ideally, solar panels should have an orientation and tilt angle that will maximize the amount of sunlight received during the year. On a flat commercial roof, this can be easily accomplished with a ballasted system with the optimal tilt angle. There are also tracking systems that keep solar panels pointed towards the sun, but these are better suited for ground installations.
Solar panels become more productive when they have optimal placement, but only if the area is not covered by shadows. Compared with homes, commercial buildings are less likely to be shaded by trees or other buildings. However, keep in mind that shadows move during the day, and a roof area that is clear during the morning may be completely shaded in the afternoon. Solar designers use special software that simulates the sun’s movement during the entire year, to determine the optimal layout for a PV system.
) Make Sure Your Commercial PV System Is Properly Sized
Your roof design can be optimized if the size and layout of your solar array is known in advance. However, an undersized system will achieve minimal savings with respect to your power bills, while an oversized system brings unnecessary costs. To find the ideal size of a commercial solar array. there are two important factors to consider:
- The energy consumption profile of your building.
- Local net metering regulations: How are you paid for surplus power?
Solar panels reach their peak productivity around noon, and a large array will probably exceed your building consumption at that time. Surplus production is not a problem if your electricity provider offers net metering, but keep in mind this benefit is not available in some place.
If net metering is not available, your solar array should be sized according to your consumption, avoiding surplus production as much as possible. With net metering you can use a larger array, since surplus production is also subtracted from your consumption.
Just keep in mind that net metering conditions vary depending on the electricity provider, and there is normally a maximum credit you can get. There are cases where you can reduce your power bill to zero with net metering, and unused credit is often rolled over to the next month. However, net metering programs that pay you in cash for credits are extremely rare. This means you cannot increase the size of a commercial solar array indefinitely with the intention of billing your power company.
) Consider Zoning Regulations, Building Codes and Local Laws
Last but not least, you must consider all local requirements for commercial solar power before starting your project. For example, your city may have historic districts where solar panels are not allowed. The opposite can also happen: In New York City, Local Laws 92 94 of 2019 require sustainable roofing systems in new constructions, renovations and roof replacements. You can meet this law with either solar panels or green roofs, but the ROI offered by solar power is better.