How Many Solar Panels Do I Need?

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How Many Solar Panels Do I Need

At Smart Solar Energy Co., one of the most common questions our customers ask us is “how many solar panels do I need?” Most homeowners want to purchase a solar system that will completely offset their power bill. To get an idea of how much solar energy you might produce with your solar system, you can calculate the size of the system that will produce enough energy to power your household. This comes down to finding out how many kilowatt-hours (kWh) of power you use, and finding the size and number of solar panels that will produce that same amount of kWh.

Home with solar panels

Keep in mind that this is more of an academic exercise than a realistic one—even if you can calculate the exact number of solar panels you will need to meet your home’s energy consumption, there are many other factors that will affect the size and production power of your solar system. The size of your roof, how much shade it receives, and its orientation in relation to the sun will all play a part in determining how many solar panels your system will have. Installing enough solar panels to offset your entire power bill isn’t always doable, because the size of your roof and/or the amount of shade it receives may dictate fewer panels. This is particularly common in the Pacific Northwest, based on the average roof size and the amount of shade most homes receive. However, you will still save a significant amount of money on energy, even if your solar system is not large enough to offset your entire power bill!

home with solar

To get a true understanding of not only your home’s solar energy needs, but how much solar energy you can realistically expect your home’s system to produce based on all of these factors, we recommend getting a professional solar audit. Our audits are free and can be done remotely or in-person.

How Many Solar Panels Will I Need?

On average, most homes in the Pacific Northwest would require about 36 solar panels to completely offset their power bill with solar energy. This is based on the assumption that your solar system uses 25-watt panels and your home consumes about 10,400 kWh of energy each year. This is based on the averages provided by the US Energy Information Administration (EIA). According to the EIA, the average US household consumed 877 kWh per month and 10,679 kWh annually in 2019. We also used the average solar production ratio for the Pacific Northwest of 1.15 per panel. Using these numbers, we divided the average household’s energy use (10,400) by the production ratio of 1.15, then again divided that number by 250 (which is the typical wattage of a solar panel).

To find the true number of panels needed for your personal household needs, you can do some calculations. If you take a look at your utility bill, you should be able to find your total power consumption for the last year on your statement. Look at your total kWh used in the last year. For context, one kWh indicates 1,000 watts of power in one hour. A standard lightbulb is 60 watts, so if you have 30 lights on in your house for an hour, and each light is using a 60-watt lightbulb, you would use 1,800 watts of power, or 1.8 kWh of energy. Once you’ve found your household’s total kWh used in the last year, divide that number by the correct solar panel production ratio for your region (1.15 if you’re in Oregon or Washington), then divide the resulting number by 250. The total should tell you the number of solar panels you would need to offset 100% of your home energy needs.

Solar Panel Production Power

As we mentioned before, there are several factors that influence the actual amount of solar energy your home’s solar panels can produce. Primarily, the amount of direct sunlight your roof receives, both based on your roof’s size and the actual weather and climate in your area. While homes in the Pacific Northwest receive less sun than homes in, say, Arizona, its still possible to install enough solar panels to meet most, if not all, of your energy needs. To do so, you may need to install more solar panels, or solar panels with higher efficiency rating, than an Arizona homeowner may need. However, as we mentioned before, it’s also not necessary to completely offset your power bill in order to save money with solar, so you don’t necessarily have to install more solar panels.

The average size of a solar system in the US is 5 kW, which will produce approximately 7,000 kWh annually using about 20 solar panels. By contrast, a 10 kWh solar system produces an average of 14,165 kWh with an average of 40 solar panels. This is assuming your solar system uses standard efficiency 250-watt panels. If you use high-efficiency panels, you may need fewer solar panels to produce the same amount of energy. For example, the 5 kW system would use about 300 square feet of roof space with low-efficiency panels, and only about 225 square feet of roof space using high-efficiency solar panels. The 10 kW system would use approximately 600 square feet of roof space using low-efficiency panels, but it would only use about 450 square feet using high efficiency solar panels. So, the efficiency of your solar panels is a major factor in determining how many solar panels you will actually need. Generally, if you have a smaller roof or a roof that receives a lot of shade, you want to seek higher-efficiency solar panels for the most effective home solar system possible. Our free home solar audit will determine your roof’s solar capabilities, based on its size, orientation, and shading, to give you a full breakdown of how many solar panels you will be able to install. Your home solar audit can be done in-person or, using our state-of-the-art technology, we can conduct accurate audits virtually as well.

Consider Your Future Energy Needs

In addition to your current energy usage, an important thing to consider when determining your energy needs is a full breakdown of any planned upgrades to your home that might increase your energy consumption. Air conditioners, central air, hot tubs, electric vehicles, and heated swimming pools are major consumers of energy. Add-ons like these will dramatically increase your home’s energy consumption. Powering a hot tub or an electric vehicle would require about 10 solar panels each to be fully powered by solar energy. While using solar panels to power any of these add-ons will drastically reduce your carbon footprint, it’s important to understand all of the potential energy needs you will have in the future when considering your solar panel install project.

Choosing Solar Panels: Look for American-Made

There are a few key components that we always recommend our customers seek when choosing their solar panels. First, we always recommend you opt for American-made solar panels. This is important because it means your hardware has been manufactured according to the US’s rigorous production standards. If you choose solar panels made elsewhere, such as China, your solar panels have been manufactured according to lower quality standards than the ones the US maintains. You can also feel good about your purchase—in addition to massively reducing your carbon footprint by going solar, you’re contributing to the US economy and supporting US manufacturing jobs by purchasing American-made solar panels. Of course, American-made goods are often more expensive, but that’s not always the case with solar panels. At Smart Solar Energy Co., we receive volume discounts from our solar panel hardware companies that allows our US-made solar panels to remain competitive, price-wise, with solar panels that are manufactured in Asia.

Choosing Solar Panels: Review the Warranties

Two important considerations when selecting your solar panels are the manufacturer warranty and the production warranty. All solar panels should come with a manufacturer warranty. This is a contract that guarantees the actual hardware of your solar panels—if the panels malfunction or experience damage, the manufacturer will perform the necessary repairs or replace your solar panels at no cost during the warranty’s specified time period. It’s common to see 10-year manufacturer warranties, but we recommend seeking a 15-year warranty in order to ensure the longest term of protection for your solar investment. At Smart Solar Energy Co., we exclusively work with solar panel manufacturers that offer 15-year warranties, and we also guarantee our solar panels for an additional 10 years beyond the manufacturer’s warranty. This means that if your panels are damaged or malfunction during the 15-25 year window after your installation, we perform the repairs or replace your solar panels free of charge.

The production warranty on your solar panels guarantees a minimum amount of solar energy output that your panels will produce for a specified window of time. This is an important factor because it gives you an exact timeline for the degradation of your solar panels. While solar panels generally have a very slow degradation rate, it’s important to look for the best production warranty possible in order to get the best return on your investment in solar for the long haul. Both 20 and 25 year solar panel production warranties at 80% are common, which means the solar panels are guaranteed to produce at least 80% of their original production power for 20 or 25 years after you install them. However, it’s possible to find higher production power guarantees. At Smart Solar Energy Co., we guarantee our solar panels at 85% for 25 years.

If you purchase a 300 watt solar panel system with a 25 year 80% production warranty in 2021, your solar panels will still be producing 240 watts of solar energy in 2046; if you purchase the same solar panel system, but with a 25 year warranty at 85% production, your solar panels will be producing 255 watts in 2046.

Choosing Solar Panels: Polycrystalline vs. Monocrystalline

While the price, quality, and durability of your solar panels should be the most important factors in your purchase, the look of the solar panels you choose should be a consideration as well. Your solar panels are going to be visible on your home every day for at least 25 years, so you want to be happy with the way they look. There are two types of solar panels, each with a slightly different look: polycrystalline solar panels and monocrystalline solar panels. Polycrystalline solar cells are blue and they have a crystal pattern, and monocrystalline solar cells are black. Polycrystalline solar cells are made by combining many silicon crystals together and cutting cells from the blend of silicon. Monocrystalline cells, however, are composed from a single silicon crystal. The majority of homeowners opt for monocrystalline solar panels because the all-black solar panel array tends to look cleaner and simpler. Luckily for design-minded homeowners, monocrystalline solar cells also happen to be the more efficient of the two.

Home with solar panels

Getting the Best Price on Solar Panels

Now that you have an understanding of the factors that influence a solar panel installation, we suggest doing your research and getting quotes from multiple solar installers. Look for an installer that offers free home audits, assists with your incentive paperwork, offers robust labor and hardware warranties, and guarantees your solar panels at least 85% production power for 25 years. Of course, price is a factor here as well. While some consumers often assume the biggest solar panel installers will offer the best price, this isn’t always true. Compare prices from the large, national-scale solar companies with regional solar dealers (like Smart Solar Energy Co.) to get the best price on your solar install project. Soliciting multiple bids will also allow you to compare your hardware options. Look at the efficiency, warranties, and of course, price—you want efficient solar panels, but the most efficient panels will also be the most expensive, so comparing multiple offers will allow you to find the sweet spot between price and efficiency.

Additional Decisions to Consider When Going Solar

There are several other major decisions you will need to consider when you make the switch to solar energy—primarily, which type of solar system you opt for. There are three types of solar systems: grid-tied solar systems, which are the cheapest and the most common type of solar installation; off-grid solar systems, which are far more expensive and less common; and hybrid solar systems, which are increasing in popularity.

Grid-tied systems are simple solar install project that keep your home connected the the utility grid. These systems allow you to take advantage of the utility grid when your solar panels aren’t producing energy at night or during the darker winter months. Net energy metering allows you to save massively on your power bill while still using the utility grid for energy when you need to. For homes in the Pacific Northwest, where it’s often difficult to install a solar system that will completely offset all of your home energy needs, this is a cost-savvy option that allows you to effectively lower your carbon footprint and save money with solar with however many solar panels your roof can reasonably support.

Off-grid systems are complex solar install projects that are typically done on large properties or farms. These are solar panel systems that are completely disconnected from the power grid, for homeowners who wish to be fully self-reliant. Because these systems are not connected to the grid, they require a surplus of solar panels, often installed on ground mounters in addition to the home’s roof. In order to ensure homeowners with off-grid systems don’t run out of electricity, it’s often necessary to install multiple backup batteries to store excess energy that the solar panels produce when it’s sunny.

Off grid solar system diagram

Hybrid systems are solar panel installations that use one or multiple backup batteries, but still remain connected to the power grid. These systems allow homeowners to bank all of the extra energy their solar panels produce when it’s sunny, storing it in the backup battery to be used later, rather than sending the excess energy back to the power grid in exchange for net metering credits. These systems are rising in popularity as some utility companies have begun to change their net metering policies. Hybrid systems also allow you to retain power if the grid goes down, by drawing stored energy from the solar battery. If your utility company is not offering one-to-one credits for net metering, or you live in an area that experiences frequent power outages, a hybrid solar system may be the best option for you.

solar hybrid diagram

Once you’ve decided which type of solar system you want, there’s the question of how you will pay for it. There are excellent state and federal incentives in place that make switching to solar more cost-effective than ever, and switching to solar is not the giant expense that many think it will be. At Smart Solar Energy Co., we typically recommend financing your solar system, and we partner with local banks and credit unions that offer low-interest solar loans. Financing is an excellent option because it allows you to pay for your solar system over several years, rather than in one lump sum. You don’t need to pay anything down or save up in order to go solar if you opt to finance. Leasing from a third party is an option, but we discourage our customers from making this choice. When you lease your solar system, you don’t receive the benefits of owning your own power source, and you lose out on all of the valuable incentives when you lease your solar.

Finally, there’s the question of when to go solar. While it may seem ideal to wait for the prices of solar to decrease, the smart thing to do is to make the switch now, with the Federal Solar Investment Tax Credit at a high of 26%. The ITC is a cash rebate available to homeowners who purchase a solar system. When you file your taxes for the year you switch to solar, 26% of your solar system’s total cost, dollar-for-dollar, will be removed from your overall tax burden. This incentive remains in place through the end of 2022. In 2023, the credit will be reduced to 22%, and in 2024, it goes away entirely. The federal ITC is the biggest solar incentive available, and there’s no limit to how much it’s worth or how many homeowners can take advantage of it. Additionally, as we mentioned above, many utility companies are changing their net metering practices and crediting homeowners for less than the amount of energy they feed to the grid, rather than giving equal energy credits to the amount of energy homeowners contribute. However, you are locked into whatever net metering practices are in place at the time of your solar install, even if your utility company changes its policies later. Solar incentives are designed to increase the demand for solar, and as the demand rises, the incentives will continue to decrease. For these reasons, we highly recommend making the switch to solar sooner rather than later.

To find out if your home qualifies for solar and how many solar panels you will need, schedule your free virtual or in-person home solar audit today!

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