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How Much Roof Space Is Needed For Home Solar Panels. Solar system home fitting

How Much Roof Space Is Needed For Home Solar Panels. Solar system home fitting

    Should I install solar panels at home?

    From installation costs, to money saved on energy bills, here’s everything you need to know about installing solar panels at home.

    Having solar panels installed at home sounds like an appealing idea. You get free electricity when the sun shines, potentially cutting your energy bills and doing your bit for the environment without having to give it much additional thought.

    Experts say that cutting the carbon emissions associated with powering and heating our homes, which emit a fifth of the UK’s CO2, is crucial if the country is to reach its target of being net zero by 2050.

    And at a time when energy costs are soaring and more and more of us want to do our bit for the environment, fitting solar panels on your home has never seemed more attractive. But what are the pros and cons of installing solar panels — both environmentally and financially speaking?

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    Why install solar panels at home?

    Consumers are becoming increasingly aware of the need to use ‘green’ or renewable energy. New research from Citizens Advice reveals that two-thirds of householders are thinking about making their homes more energy-efficient in the next 12 months, while in a study from NatWest 55% of homeowners said they have plans to make eco-friendly improvements to their property over the next decade.

    Solar and wind are now the lowest cost ways to generate electricity and, unlike other more traditional types of energy, they won’t run out. It’s not surprising, then, that fitting solar panels on the roofs of domestic properties is a popular home improvement, with an estimated one million systems on houses across the UK. They are not cheap, but in the longer term they should help cut your electricity bills as well as your carbon footprint, while you also get paid for the extra energy you generate.

    How do solar panels work?

    Solar electricity panels, also known as photovoltaics (PV), capture sunlight and convert it into electricity which can then be fed into your home’s main electricity supply. A solar PV panel consists of many cells made from layers of semi-conducting material, typically silicon. When light shines on it, a flow of electricity is created which means you can generate your own renewable electricity.

    The electricity produced by your solar panels will be used to power any appliances that you’re using in your home at the time the energy is generated. Any surplus electricity which is not used will be sent to the grid, for which you will be paid.

    If you’re researching solar panels, you may also come across thermal solar panels but these are only used to heat water.

    How much do solar panels cost?

    That depends on your choice of panels. This, in turn, will be determined by how much electricity your household uses, how much roof space you have, and how much money you’re willing to spend.

    A single solar panel can cost between £350 and £500. One of the popular domestic sizes is a 4kWp system, which will cost around £6,000 and typically cover around 29 square metres of roof. The Energy Saving Trust (EST) says the average domestic solar PV system is 3.5kWp and costs around £4,800 (including VAT at 5 per cent). This will typically take up around 15-20m2 roof area, making it suitable for the average terraced house.

    How much do solar panels cost to install?

    Much of the cost associated with solar panels comes from installation, and the Energy Saving Trust (EST) recommends getting quotes from at least three installers.

    Some of the installation costs can be shared if you already have scaffolding up for roof repairs or if you are building a new house. Costs are also affected by whether you choose panels or tiles, and whether you opt for building-integrated panels or choose panels that sit on top of your roof. Panels on top of the roof are the cheapest option, while tiles are the most expensive for the equivalent system.

    Will installing solar panels really save me money?

    How long it will take for your solar panels to pay for themselves, and whether you can make money from them, will depend on the cost of your solar PV system, how much of the electricity generated you are able to use and whether (and how much) you are paid for any surplus electricity.

    Generally, solar panels installed on the roofs of homes and buildings won’t give much financial payback for the first 20 years or so, according to Mike Childs, head of science at Friends of the Earth. “But there are huge environmental benefits, depending on where you live and how much electricity you use” he says. “The average person contributes 12.7 tonnes of carbon per year, but by installing solar panels around 1 tonne of carbon can be saved annually, so the potential is significant.”

    Can I make money from the energy my solar panels generate?

    If you have a solar PV system and generate more power than you need, the surplus will go back into the national energy grid. Under the Smart Export Guarantee (SEG), which was launched in January 2020, electricity suppliers offer payment for each unit of power you export to the grid. The previous feed-in tariff scheme was far more generous, but it closed for new customers at the end of March 2019.

    If you’re selling electricity back to the national grid, you can select the best SEG tariff available, separate from any contract you have with an energy supplier that powers your home.

    SEG tariffs can be fixed or variable. A fixed SEG tariff will pay a determined rate per kWh of electricity exported over the length of the contract. A variable SEG tariff will vary the price based on market demand, with the only requisite that never fall below zero.

    Solar Energy UK has a helpful league table which reveals which suppliers currently offer the best rates. Alternatively, Ofgem publishes a list of SEG licensees every year and you can contact an energy company directly for more information on its tariffs.

    The Energy Saving Trust estimates that a household in London could save around £295 a year on its energy bills by having solar panels installed if there is usually someone at home all day, and could save an additional £90 a year by selling surplus energy under the Smart Export Guarantee.

    How can I find the best deal on solar panels?

    If you’re considering installing solar panels at home, it’s worth finding out if you could be eligible for funding or financial help. Elliot Clark, project officer in the home energy team at the Centre for Sustainable Energy, said: “Start with your local council as authorities may be awarded funding to install solar panels on suitable houses, although it is likely to be reserved for homes with a lower household income or those in receipt of mean tested or disability benefits.

    The Microgeneration Certificate Scheme (MCS) provides a list of accredited installers. Clark adds: “We recommend going onto the government’s Trustmark website where you can search by area and solar panel installer. There’s also the Renewable Energy Consumer Code which installers can sign up to.”

    How can you make the most of the energy you generate?

    To make the most of the energy you get from your solar panels, think carefully about when you use your appliances.

    Elliot Clark says: “Saving running appliances such as dishwashers and washing machines for the sunniest parts of the day will make your usage more efficient. You can also get a solar diverter if you have or are thinking of getting a hot water cylinder or thermal store, so any electricity generated that your property does not use can be diverted to heat water for you to use for washing or heating.

    Hot water cylinders are likely to make a comeback as they are often used with heat pumps, and storing your excess electricity as hot water will reduce the demand of energy of your heat pump.”

    Batteries could be another way for homeowners to store excess electricity produced by their solar panels to use at another time but there’s still some way to go before the technology makes this a viable option. Currently, these special batteries are bookcase size, and are so expensive and the cost would likely outweigh the benefits. They can also only store energy for a certain amount of time — typically for a few weeks, at the most.

    What are the disadvantages to solar panels?

    The main barrier is the length of time you’ll need to wait to see a return on your investment, and the difficulty of calculating it in advance.

    Installation can be expensive and solar panels’ performance can be adversely affected by weather. more of an issue in the UK than places such as the USA and Australia. Not all roof types are suitable, and panels can look ugly and take up a lot of space.

    The production of solar panels is also not very eco-friendly; Friends of the Earth points out that 80% are made in China where manufacturing is largely powered by coal. They are also expensive and impractical to move, which may be an issue if you are likely to move house.

    In a major report based on its own consumer complaints, Citizens Advice has expressed concern about mis-selling and cold-calling by rogue solar panel installers. It says many consumers have ended up signing up for contracts they don’t fully understand which leave them worse off than when they started out.

    It is calling on the government to introduce protection through a net zero homes guarantee.

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    We cut our energy bills by £1,000 a year

    Catherine Macneil, 61, and her husband Richard moved to a converted detached farmhouse dating back to 1800 in Mollinsburn, Scotland, in 2011. They were keen to avoid the “extortionate” energy bills of their previous home, which was also in a rural area.

    After getting advice from Home Energy Scotland, Catherine decided to have solar panels installed along with a solar water heating system and a biomass wood-pellet boiler.

    All three renewable technologies came in within her budget at around £25,000. She covered half of the cost with an interest-free Home Renewables Loan from the Energy Saving Trust. At the time the couple was also able to take advantage of feed-in tariff payments.

    Since installing these technologies and by selling their surplus energy back to the national grid, the couple has enjoyed savings of around £1,000 every year on their energy bills.

    “Our electricity bills are currently slightly less than £50 per month. so £600 per annum. and our our feed-in tariff last year was £1785 so that gives over £1000 towards our wood pellets” explains Catherine. “They cost roughly £2600 per annum. Without the feed-in money it would be difficult.”

    Overall, she says, “I feel better for having the solar panels. They are not intrusive and we are all trying to be greener these days so this is our contribution.”

    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.

    Solar installations are getting easier all the time and there’s plenty of do-it-yourself information out there. But are you ready to go the DIY route?

    If you’re interested in solar power, surely you already know that solar electricity is good for the environment, national security, and the air we breathe, not to mention your electricity bill. And that it’s one of the best ways to reduce your household’s contribution to global warming. You’ve also probably heard that going solar can actually be cheaper than paying for utility power, and you might wonder whether this claim is true. Well, in most cases, it is true. It just takes time for the incremental savings to overtake the initial investment (after that, the solar power is free). If you install the solar system yourself, you can hit this tipping point a lot sooner — in some cases, in half the time.

    That brings us to the next big question: Can you really install your own solar panels? Again, the answer is yes. If you can drive lag bolts and assemble prefabricated parts, and if you’re willing to spend a day or two on your roof (or not, if you’re mounting your panels on the ground), you can install your own solar system. You don’t have to know how to hook up the solar panels to your household electricity or the utility grid. You’ll hire an electrician for the house hookup, and the utility company will take care of the rest, usually for free. For a completely off-grid system, the utility company isn’t involved at all.

    Perhaps disappointingly, this job isn’t even a good excuse to buy new power tools, since the only one you need is a good drill.

    much, roof, space, needed, home

    So, if this is such a doable project, why do most people use professional installers? For starters, a lot of people have good reasons to hire out virtually everything, from oil changes to grocery shopping. (That’s probably not you, but even if it is, our book can help you plan for a solar installation and find a good local installer.) Solar professionals handle more than the installation. They design the system, they apply for rebates and credits, they order all the necessary parts, and they obtain the permits and pass all the inspections. But the fact is, you can do all of these things yourself, provided you have a helpful adviser and you are willing to follow the rules of the local building authority (that’s where you’ll get those permits).

    Solar installations are getting easier all the time, and you might be surprised at how much do-it-yourself (DIY) help is available. Two good examples are PVWatts and the Database of State Incentives for Renewables Efficiency (DSIRE). PVWatts is an online calculator that helps you size a solar-electric system based on the location and position of your house and the angle of your roof. Solar pros use the same simple tool, but it’s free for everyone. DSIRE offers an up-to-date, comprehensive listing of renewable energy rebates, tax breaks, and other financial incentives available in any area of the United States. And it’s also free and easy to use.

    Those two resources alone help answer the two most common questions homeowners have about solar electricity: How big of a system do I need? and How much will it cost? Other resources include solar equipment suppliers that cater to DIYers and offer purchasing and technical support, as well as online communities like Build It Solar. And there’s no law that says DIYers can’t hire a solar professional for help with specific aspects of their project, such as creating design specifications, choosing equipment, or preparing permit documents.

    We should also say up front that installing your own solar panels is not a process well-served by cutting corners. We don’t want you to install your system without a permit or without hiring an electrician to make the final hookups. (Even professional solar installers use electricians for this stuff.) The permit process can be a pain, yes, but it’s there to ensure that your system is safe, not just for you but also for emergency responders who might need to work around your mini power plant. When you work with the local building department you also learn about critical design factors, such as wind and snow loads, that are specific to your area.

    Can I Install My Own PV (Photovoltaic) System? A DIYer’s Checklist

    It’s time for the litmus test that tells you whether to proceed boldly as an amateur solar installer or to hand over the reins to a professional. For most of you, the decision will come down to the rules of the local building authority (most likely your city, county, township, or state) or your utility provider, either of which may require that solar installations be done by a licensed professional. This is also the best time to confirm that your project won’t be nixed by your zoning department, historical district standards, or your homeowner’s association.

    • Amateur installation is permitted by the local building authority and your utility provider.
    • Requirements for amateur installation are reasonable and acceptable. Some authorities require nonprofessionals to pass tests demonstrating basic knowledge of electrical and other household systems, but such tests may not be extensive.
    • You’re okay with several hours of physical rooftop work (those with ground-mount systems get a pass here) AND you’re wise enough to wear legitimate fall-arresting equipment (not a rope tied around your waist). You may feel as confident as Mary Poppins dancing on rooftops, but she can fly; you should be tethered.
    • You don’t live in a historical district or, if you do, the zoning authority permits PV systems (with acceptable restrictions).
    • Your homeowner’s association, if you have one, permits PV systems (with acceptable restrictions). Sometimes the homeowner’s association may need a little nudging to give permission.
    • You have a standard type of roofing (asphalt shingles, standing-seam metal, wood shingles, standard flat roof). If you have slate, concrete tile, clay tile, or other fragile/specialty roofing, consult a roofing professional and/or hire out the PV installation. This is not necessarily a deal-breaker.

    TEXT EXCERPTED FROM INSTALL YOUR OWN SOLAR PANELS © JOSEPH BURDICK AND PHILIP SCHMIDT.

    Install Your Own Solar Panels

    Labor and related costs account for more than half of the price of the average home solar installation. But homeowners can save thousands of dollars with this user-friendly manual, which follows the same process professional contractors use. Through detailed directions and step-by-step photos, veteran solar installer Joseph Burdick and seasoned builder Philip Schmidt teach you how to determine the size, placement, and type of installation you’ll need. This comprehensive DIY guide covers everything from assembling rooftop racking or building a ground-mount structure to setting up the electrical connections and making a battery bank for off-grid systems.

    The Cost of Solar Panels: Is It Worth It?

    Do the benefits of solar panels outweigh their costs?

    Nathaniel Riley brings 28 years of experience in financial services, including merger-arbitrage trading, hedge funds, and alternative investments.

    ​Somer G. Anderson is CPA, doctor of accounting, and an accounting and finance professor who has been working in the accounting and finance industries for more than 20 years. Her expertise covers a wide range of accounting, corporate finance, taxes, lending, and personal finance areas.

    Skylar Clarine is a fact-checker and expert in personal finance with a range of experience including veterinary technology and film studies.

    What Is Solar Power for the Home?

    Homeowners who install solar power systems can receive numerous benefits: lower electric bills, lower carbon footprints, and potentially higher home values. But these benefits typically come with significant installation and maintenance costs and the magnitude of the gains can vary widely from one house to another.

    This article will help homeowners make the financial calculations required to determine the viability of solar power in their homes.

    Key Takeaways

    • Those seeking to go green may want to consider equipping their home with solar panels.
    • Not only is solar power good for the environment, but you can earn money selling back excess power to the grid.
    • While costs have come down over the past years, installation and maintenance of solar panels can be quite expensive.
    • Solar panels are best suited for homes that receive ample sun exposure throughout the year.
    • Before committing to solar power, be sure to understand both the social and economic factors.

    Understanding Solar Power

    In principle, working out whether it makes financial sense to install solar power for your home is simple. You will need to calculate:

    • The cost of a solar power system
    • How much energy it will produce
    • What you would otherwise pay for the same amount of energy
    • How many years it will take for your upfront investment to pay for itself in saved energy costs
    • Whether the system will pay for itself in five years

    If it does and you have the upfront capital, it’s probably a great idea. If you’ll have to wait longer for savings or take out a loan to afford the system, you’ll need to think the decision through carefully.

    In practice, however, things are not this simple. There is a large variation in each of these factors, and that can make the costs and benefits of installing solar power for two homes—even if they are neighbors—radically different.

    There are some tools that can help, though. Solar Reviews offer a calculator that will quickly provide you with representative costs and savings for a solar power system in every part of the U.S. Calculators like this are a good place to start if you are new to solar energy and want to understand the basic cost model.

    In the rest of this article, we’ll take you through each of the key factors you should consider when calculating the costs and potential savings of solar power for your home.

    Before getting solar panels, get quotes from several reputable installers to compare.

    The Cost of Solar Power for Homeowners

    First, let’s look at the cost of installing a solar power system for your home. The average, upfront cost of a residential solar power system is between 3,500 and 16,000.

    Why the huge range of costs? Well, a lot of the variation depends on the size of the system you’d like to install and the type of panels you want to use. Whatever system you use, keep in mind that solar power is capital intensive and the main cost of owning a system comes upfront when buying the equipment. The solar module will almost certainly represent the largest single component of the overall expense.

    There are some additional costs, as well. Other equipment necessary for installation includes an inverter (to turn the direct current produced by the panel into the alternating current used by household appliances), metering equipment (if it is necessary to see how much power is produced), and various housing components along with cables and wiring gear. Some homeowners also consider battery storage. Historically, batteries have been prohibitively expensive and unnecessary if the utility pays for excess electricity that is fed into the grid (see below). The installation labor cost must also be factored in.

    In addition to installation costs, there are some further costs associated with operating and maintaining a PV solar array. Aside from cleaning the panels regularly, inverters and batteries (if installed) generally need replacement after several years of use.

    Subsidies

    While the above costs are relatively straightforward—often a solar installation company can quote a price for these for a homeowner—determining subsidies available from the government and/or your local utility can prove more of a challenge. Government incentives change often, but historically, the U.S. government has allowed a tax credit of up to 30% of the system’s cost.

    details on incentive programs in the U.S., including programs within each state, can be found on the Database of State Incentives for Renewables Efficiency (DSIRE) website. In other countries, such information is often available on government or solar advocacy websites. Homeowners should also check with their local utility company to see whether it offers financial incentives for solar installation and to determine what its policy is for grid interconnection and for selling excess power into the grid.

    97.7 gigawatts

    The U.S. installed 19.2 gigawatts of solar PV capacity in 2020 to reach 97.7 GWdc of total installed capacity, enough to power 17.7 million American homes.

    Calculating Your Energy Production

    The second factor you’ll need to consider in your calculations is the amount of energy your system will produce and when it will do that. This can be a very complicated calculation to make, even for experienced solar engineers. However, let’s run through the basics.

    One of the most important considerations is the solar irradiation levels available in the home’s geographical location; in other words, how sunny it is where you live. When it comes to using solar panels, being closer to the equator is generally better, but other factors must be considered. The National Renewable Energy Laboratory (NREL) produces maps for the U.S. showing solar irradiation levels and the tools on its website provide detailed solar information for specific locations within the U.S.

    Equally important is your home‘s orientation: For rooftop arrays, a south-facing roof without trees or other objects obstructing sunlight maximizes the available solar energy. If this is not available, panels can be mounted on external supports and installed away from the house, incurring additional costs for the extra hardware and cables.

    And then you must factor in the size of your system. Solar panel size is quoted in terms of the theoretical electrical output potential in watts. However, the typical output realized for installed PV systems—known as the capacity factor—is between 15% and 30% of the theoretical output. A 3 kilowatt-hour (kWh) household system running at a 15% capacity factor would produce 3 kWh x 15% x 24 hr/day x 365 days/year = 3,942 kWh/year or roughly one-third of the typical electricity consumption of a U.S. household.

    How Much Will You Save?

    Once you know how much a solar power system will cost upfront, and how much energy it will produce, you can (theoretically) predict how much you can save in energy costs per year.

    This is another tricky calculation, however, because a lot depends on how you pay for electricity at the moment. Utilities often charge residential consumers a flat rate for electricity, regardless of the time of consumption. This means that instead of offsetting the expensive cost of peak electricity production, homeowners’ solar power systems merely offset the price they are charged for electricity, which is much closer to the average cost of power production.

    However, many utility companies in the U.S. have introduced pricing schemes that allow homeowners to be charged at different rates throughout the day in an attempt to mirror the actual cost of electricity production at different times: This means higher rates in the afternoon and lower rates at night. A PV solar array may be very beneficial in areas where this sort of time-varying rate is used since the solar power produced would offset the most costly electricity.

    Exactly how beneficial this is for a given homeowner depends on the exact timing and magnitude of the rate changes under such a plan. Similarly, utilities in some locations have pricing schemes that vary over different times of the year due to regular seasonal demand fluctuations. Those with higher rates during the summer make solar power more valuable.

    Some utilities have tiered pricing plans in which the marginal price of electricity changes as consumption rises. Under this type of plan, the benefit from a solar system can depend on the electricity use of the home; in certain areas subject to rates that increase dramatically as consumption increases, large homes (with large energy needs) may benefit most from solar arrays that offset high-cost marginal consumption.

    For some homes, it might even be possible to make money by selling solar power back to the grid. In the U.S., this is done through net metering plans, in which residential consumers use the power that they put into the grid (when the rate of electricity generation from the solar array is greater than the rate of household electricity consumption) to offset the power consumed at other times; the monthly electric bill reflects net energy consumption. The specific net metering regulations and policies vary across regions. Homeowners can refer to the DSIRE database and should also contact their local utilities to find more specific information.

    Calculating Solar Power Costs

    At this point, you will be in a position to make a final calculation, and an assessment of whether solar power makes sense for you.

    The overall cost and benefit of a solar system can theoretically be evaluated using the discounted cash flow (DCF) method. Outflows at the beginning of the project would consist of installation costs (net of subsidies) and inflows would arrive later in the form of offset electricity costs (both directly and through net metering).

    However, rather than using DCF, the viability of solar power is usually evaluated by calculating the levelized cost of electricity (LCOE), then comparing it to the cost of electricity charged by the local utility. The LCOE for household solar will typically be calculated as cost/kilowatt-hour (/kWh or ¢/kWh)—the same format commonly used on electricity bills. To approximate the LCOE, one can use the following equation:

    LCOE (/kWh) = Net Present Value (NPV) of the Lifetime Cost of Ownership / Lifetime Energy Output (kWh)

    The useful life of a PV solar module is generally assumed to be 25 to 40 years. The cost of ownership includes the maintenance costs, which must be discounted to find the NPV. The LCOE can then be compared to the cost of electricity from a utility; remember, the relevant price is that which occurs during times at or near peak PV solar production.

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    Is Solar Power Worth It?

    Once you’ve worked through all of these calculations, you’ll likely end up with a single number—the number of years it will take for a solar system to pay for itself in savings from your energy bills. If you live in a sunny part of the country and have high utility bills at the moment, you could be looking at a system that will reach this point in five years. Other homeowners may have to wait 10 or 20 years to reach this point.

    In other words, most homeowners will eventually see a benefit from a solar power system; it might just take decades for this to be realized. Whether it is worth installing such a system therefore often comes down to a number of much less technical factors than those we’ve listed above: how long you are going to stay in your home, the subsidies available in your area, and simply whether you want to do your bit for the environment.

    Pros and Cons of Solar Panels for Your Home

    Like most things, solar power has its benefits and drawbacks. At the same time, some economic costs may be defrayed by the social benefits to the environment and lowering your carbon footprint, which may be more important to you than a purely monetary evaluation.

    • Green energy that lowers your carbon footprint
    • Net metering allows you to sell back excess energy produced
    • You may be eligible for certain tax breaks
    • Installation and maintenance costs are still high
    • Solar only works when the sun is out
    • Parts of the system need to be replaced every few years
    • Some tax breaks may have expired or will be expiring

    Can a House Run on Solar Power Alone?

    Practically, it is not often possible. This is because solar only works when the sun is shining—when it is cloudy or nighttime, they do not generate electricity. There are some battery solutions to provide power during these times, but they still tend to be quite expensive. Most homes with solar panels still rely on the grid from time to time.

    Do You Really Save Money With Solar Panels?

    Depending on where you live, it is possible that the system can pay itself back and more over time. This is because you won’t be spending as much money buying electricity from your utility. If net metering is in place, you could reduce your bills even further.

    How Much Does a Solar Panel Cost?

    have been coming down steadily over the years. The total cost will depend on how many kilowatts of power your array will generate. According to consumer reports, after solar tax credits are accounted for, the cost for a solar panel system on an average-sized house in the U.S. in 2021 ranges from 11,000 to 15,000.

    How Long Will It Take To Recoup the Initial Cost?

    Depending on where you live and the size of your system it can take, on average, anywhere from 10 to 20 years to break even on a solar installation.

    The Bottom Line

    Determining whether to install a PV solar system may seem like a daunting task, but it is important to remember that such a system is a long-term investment. In many locations, solar power is a good choice from a financial perspective.

    Even if the cost of solar power is found to be marginally more expensive than electricity purchased from a utility, homeowners may wish to install solar power to avoid future potential fluctuations in energy costs, or may simply wish to look beyond their personal financial motivations and use solar for green living.

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