The average roof in the United States could fit about 97 solar panels. This could provide approximately 31 kW (kilowatts) of electricity.
But the average American only needs 19- 23 solar panels to power their home. Before you get excited about selling all your surplus electricity to your utility company, you need to realize that being able to accommodate a large solar system on your roof doesn’t mean that it makes sense to do so.
Installing a solar energy system in your home is an awesome way to be more sustainable and save money on your utility bills. Most solar installers prepare a unique solar layout for each customer after checking your roof and considering available space, shading, and roofing problems.
As a consumer, you have to make important decisions about how much energy you need and the details of your solar system. This includes the brand, model, size, and how many panels you need. Choosing the right solar array for your roof will ensure you get the best return on your investment.
Factors in Determining How Many Solar Panels You Need
A critical step in getting a solar installation is calculating the size of your system that you need. This is critical in determining how many solar panels you need to install.
This calculation involves not only your roof area but also your budget. Size and types of solar energy systems differ in terms of physical requirements and cost. So it is important to choose what works best for you.
Size of Your Roof
Your roof size will affect how many solar panels you can install. While you may want to start with the maximum number of panels your roof can physically accommodate, it is recommended to review your energy needs so you can make the most out of your investment and your solar panels installed in your home.
Ideally, your solar panel systems should be installed with a 40-degree pitch and no shade. If that is not possible in your area, consider other options to maximize your solar energy installation, such as purchasing more efficient solar panels.
The key thing to remember is only to measure the areas that can accommodate your solar panels. For instance, if you only want your panels to be installed on the southeast side of your home, you can measure the length of the roof along this side and then the east side from the corner where your roof ends.
But why should you measure along the wall instead of your roof area? While this may give you a less accurate measurement, it is safer. However, if you can climb up on your roof safely, this may be a better way to determine how many solar panels can fit on it.
Calculating Your Roof Space
Before you know how many solar panels you need to meet your solar energy requirements, you have to find your roof space.
To calculate your actual roof space, you need three measurements. The first is the height of the highest point of your roof to the joists (A), the second is the distance from the apex horizontally at joist level until the eaves of your roof (B), and the last is the length of your roof’s apex (C).
When you have these measurements, you will need to do some simple math.
The first formula you will need to use is:
A2 + B2 = X2
So plug in your measurements from above and solve for X. X is the distance from the apex to the edge of your roof.
After this first calculation, you can use the result to calculate the overall area of your roof as follows:
C x X = area of roof
Multiplying C and X will enable you to find out the available roof space to accommodate how many solar panels you need. Then, deduct 30cm for the edge of your roof, as this area cannot be normally used to accommodate your solar panels.
Orientation and Shading
You should position the panels on the south, south-east, or south-west facing roof. The further away your panels are from these orientations, the less effective they will be.
Aside from the orientation, you should also think about the shaded areas on your roof, especially if you have a chimney that will cast a shadow at certain times. This will decrease the amount of solar energy you can produce. In this case, position your panels out of the shadows to maximize the electricity you can generate. This may also affect the available amount of space on your roof that is suitable for installing solar panels.
Size of Your Solar Panels
While there is a common size of solar panels, you still have to research your preferred brand and model measurements. This means that the number of solar panels you can fit on your roof can vary. For example, a Tesla solar panel won’t be the same size as a solar panel from LG or Panasonic.
Pay attention to the specific measurements of your preferred brand, especially if you want to install the greatest number of panels you can fit on your roof. The average size of a solar panel is 78.74 x 157.48 cm. You can use this to calculate how many solar panels you can fit on your roof since each panel will take up approximately 1.3 to 1.4 square meters.
If you do not have enough space, you may need to invest in high-efficiency panels or those with higher power output. This way, you can install fewer panels and still cover your energy needs.
Aside from your roof size and the size of solar panels, your budget will be a major determining factor in the solar panels that get installed in your home. While you can earn your money back through savings or enjoy Federal Tax Incentives, you have to be prepared to shell a significant amount of cash. The average cost of solar panels installation is around $20,000.
Energy Usage and Production
Once you know the number of solar energy panels you can fit your roof, you need to find out how much energy your system will produce and how much electricity you consume. This will help you determine the amount of solar power you will have in surplus or deficit compared to your energy needs.
To do this, check your home’s annual energy usage on your electricity bill. For example, the average annual consumption of residential utility customers in the US in 2019 was 10,649 kilowatt-hours, with an average monthly consumption of 877 kWh.
However, your usage can vary depending on the number of people in your home, how many appliances you have, and the season.
Another factor you need to watch out for when finding out how many solar panels you need is the energy production of solar panels. Different solar panels produce varying amounts of electricity. If you choose lower efficiency panels, you need to purchase more panels to cover the energy production amount.
Number of Peak Sun Hours
The amount of sunlight in your area or peak sun hours needs to be factored in when you decide the number of solar panels you will purchase. This is the amount of intense sunlight your solar panel can receive daily.
In California, peak sun hours range from 5 to 7.5 hours daily. In Florida, the number of peak sun hours is usually 4. When multiplied by 30, this number will tell you the amount of peak sunlight you receive monthly.
This information is needed to know how many kilowatt-hours your panel can produce during peak hours. For example, if you live in Florida and receive 120 peak sunlight hours, a 1kW solar installation will monthly produce 120 kWh of electricity.
Time Spent at Your Home
If you are home at night, you will only use a small portion of the solar energy system you generate unless you also get a battery system. This is because PV panels generate solar energy during the daytime, and if you are not at home in the morning and afternoon, the power you produce will immediately go to the grid. You will be paid for this energy provided to the grid, but most of your electricity needs will not be met by your solar panel installation.
If you are at home to use the power generated by your solar panels, you can save more money than you earn from the power you feedback to the grid. With this in mind, you can install the maximum amount of panels that work with your roof area and budget. If you are only home at night, you can get a smaller system and save on the required upfront investment.
What If You Need Additional Solar Power?
After reviewing the different factors, the amount of solar power you can generate, given your space, may not be enough. If this happens, you can reduce your power consumption and make your home more energy-efficient by getting more energy-efficient appliances.
If you do not want to make lifestyle changes or switch your appliances to more energy-saving options, you can install ground-mounted solar panels instead of a rooftop system.
Is It a Good Decision to Install Solar Panels in Your Home?
Installing solar panels can be a complex undertaking. Many factors such as your solar inverter, roof shading, and roof direction can influence solar panel installations. However, these are hard to assess on your own. You may need the guidance of an experienced professional better to determine the suitability of a system for your circumstances.
The ultimate way to determine solar panel installation details, including its ideal location on your roof, is to speak to a professional solar company. Installers will also let you know the costs you will shoulder and different tax credits, rebates, and incentives available in your area that you may qualify for.
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