How Many Solar Panels Do I Need?
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How Many Solar Panels Do I Need?

Before beginning installation, first determine your home’s energy needs
Read Time: 5.5 min
Mar 30, 2022

Solar panels can be a fantastic way for homeowners to save money on electricity bills. Depending on how many solar panels you have and how much sun your location gets, you may be able to power your home on solar energy alone. Some homeowners may even have excess energy they can sell to utility companies.

Before you invest in solar panels, however, it’s important to figure out exactly how many you need. Ask yourself the following questions to determine how many you need.

What Is the Purpose of Solar Panels?

The first step is to discover exactly why you want to invest in having solar panels installed for your house. Some options include:

  • Minimizing your carbon footprint
  • Save money
  • Maximize ROI

If the solar panels are only meant to be supplementary to the power you get from the grid, then how much you want to pay to start is the only thing you need to consider. You’d just have to figure out your budget and how many panels you could get with that. If the goal is to power your entire home with the solar panels and not need to pull from the grid, then you’ll need to figure out how many solar panels are necessary to do that.

How Do you Calculate How Many Solar Panels You Need?

In order to calculate how many solar panels you would need to power your home, you would need to know the following:

  • Current energy usage (in watts)
  • Average energy needs
  • Climate for your area
  • Average sunlight for your area
  • How efficient the solar panels are
  • The size of the solar panels
  • The size of your roof
  • Tree coverage
  • How Much Energy Do You Use?

    To determine how much energy you need to power your home, check out several past utility bills. These should tell you how much power you used during that month in watts. If the utility bill doesn’t give you an average for how many kilowatt-hours your home uses, then you may have to calculate the amount based on the starting and ending meter readings. Just subtract the first meter reading from the most recent reading.

    You’ll need to know the average daily and hourly energy usage, so you may need to divide a monthly or annual usage amount by the number of days or hours during that time. On average, American homes use about 900 kWh monthly, which ends up being 30 kWh per day, or 1.25 kWh per hour. You’ll need to know how much energy you use in a day so that you can calculate how many solar panels you’ll need to meet that need.

    How Much Sun Do You Get?

    How many solar panels you need also depends on how much sunlight your home gets. If you live in Florida, any solar panels you do get are going to be more effective than if you lived in Seattle. You may be able to get fewer total solar panels if you live in a sunny area because each solar panel will have more sunlight that it can soak up.

    How Many Trees Do You Have?

    Normally shade from trees can be a wonderful thing, especially during the summer. However, the more trees you have, the less sunlight will be able to reach your solar panels. This depends on how many trees you have and where they’re placed. Your yard may be shaded but perhaps your roof gets plenty of sun. You’ll need to look at the placement of trees in your yard and figure out how much sunny space you have before determining the number of solar panels you want to be installed.

    How Much Energy Can One Solar Panel Produce?

    The amount of energy a single solar panel can produce depends on the solar panel itself as well as how much sunlight you get. Once you know how much sunlight you can expect and how much energy each solar panel can produce, you can calculate how many solar panels you need to get in order to power your entire house.

    The quality of a solar panel does matter in how much energy it can produce. At the lower end of the scale, a solar panel could produce around 150 watts of energy, while higher-end solar panels could produce as much as 370 watts.

    How Many Solar Panels Do You Need?

    Once you know how much energy you need to power your home, how much sunlight your area gets, and how much energy a solar panel could conceivably produce, you can figure out how many you need. It’s recommended to talk to the contractor who is installing the solar panels to determine exactly how many you’ll need, but you can start researching ahead of time to begin budgeting.

    Your home’s hourly energy usage X the number of peak sunlight hours ÷ wattage of a solar panel = number of solar panels you need

    How Much Weight Can Your Roof Hold?

    If you’re planning on putting solar panels on your roof, then you’ll have to consider how much weight your roof can hold. This may limit the number of solar panels that you can put on the roof. Even if you need more to power your entire home, you won’t be able to purchase more than your roof can hold unless you have another place on your property to install them.

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