How Many Solar Panels Do I Need?



Of all the questions you may ask when first considering solar,  “How many solar panels do I need?” is among the most popular for homeowners.

Have you noticed that some homes have more solar panels than others? That’s because every home has particular needs when it comes to the size of your solar system. You’ll want to know how many solar panels are needed to power your home effectively. To calculate how many solar panels you’ll need for your home, there are a number of factors to consider.

Let’s take a look at what factors are involved.

  1. Your Home’s Electricity Use
  2. Your Roof
  3. Amount of Sunshine
  4. Type of Solar Panel
  5. Your Energy Goals
  6. Solar Battery Backup Options

Factor #1: Your Home’s Electricity Use

The first question you’ll want to answer is: How many watts do you currently use?

how to read your electric billNot every house has the same amount of electricity consumption. We all know that the more you watch TV, or use your heating and cooling units, the more you’ll pay for your monthly electric bill. The more wattage a certain device or appliance uses, the more energy usage can add up for your home. Therefore, the first factor in the number of solar panels you need for your home is knowing the amount of energy you use on a regular basis (how many kilowatt (kw) hours you use).

Not sure how many watts you use? No worries. Grab your last electric bill and look for “Kilowatt Hours (kWh) Used”. This is usually represented as the amount used in your billing cycle (for example, 30 days is typical). Or you can look for the meter readings listed on your bill and subtract the beginning reading from the end reading. Reading your electric bill sometimes can be tricky, but a Solar Energy Specialist can help with this during your appointment.

Do you have an electric vehicle? Or are you planning on purchasing one in the future? If so, this is another factor in your home’s energy consumption and another thing to consider when deciding how many solar panels you will need.

What you need for your appointment: 

Copies of recent energy bills are helpful to understand how much electricity your home uses. We can also help you understand and read your monthly utility bill.

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Factor #2: Your Roof

How many solar panels you’ll end up with also depends on your rooftop. That’s because solar panels are installed on your roof, and therefore things like, available roof space, is really important in this decision.

The most ideal situation for solar panels is a roof with ample space that has an east-west ridgeline with little to no interference from trees or buildings. This will allow the panels to capture as much energy as possible from the sun.

If the space on your rooftop is limited, there are smaller higher-efficiency panels made to suit your home energy needs.

Another factor in this decision is the age of your roof. If you suspect your roof will need to be replaced soon, contact the roofing professionals at Buildpro. Read why it’s important to choose a solar and roofing company in one.

What you need for your appointment: 

Before your solar installation, it will be helpful to know the square footage of your roof and home, as well as the age of your roof. A trained Solar Energy Specialist can help you understand what all this means for your home.

Read what type of roof is best for solar panels for more information.


Factor #3: The Amount of Sunlight Your Home Gets

how much sunlight your area getsSpeaking of your roof, another important factor in the decision of how many solar panels your home will need is sunshine. How many hours of sunshine your roof gets on a daily basis, that is. How many hours of peak sunlight your home gets on average will have a direct effect on how much energy your solar energy system will be able to produce.

Read how to calculate your peak sun hours.

This resource from the National Renewable Energy Laboratory (NREL) will help you understand how much sunlight you get depending on where in the U.S. you live. If you live in the Southwest, you can expect your panels to soak in a lot more sunlight during the day than if you live in the Northeast. However, solar panels still work on cloudy days and even in the snow! The main factor of solar panels being worth it is how high electricity rates are for that particular area.


On average, a home that gets around five peak sunlight hours a day that uses around 900 kWh/month would need around 6,000 watts of solar power. How many panels this translates to depends on what type of panels you have. If you’re worried about the math, schedule an appointment with a Solar Energy Specialist who is trained to walk you through this.

What you need for your appointment: 

Just have your monthly electricity bills available and we can help you understand your peak sunlight hours as well as how this affects how many solar panels you should have.

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Factor #4: Type of Panel

Aren’t all solar panels the same? Not at all! How much power your solar power system can produce is directly affected by the type of solar panels that are installed on your home.

Here’s a breakdown: wattage and efficiency are two factors that are very important in how much power your system will produce. The more wattage, and the more efficient a solar panel is, the more output it will produce for your home.

As we just mentioned, let’s say your home needs 6,000 watts of solar energy a month. So how many solar panels does that equal? This depends on the solar panel’s wattage, the output of power for home under ideal conditions. This is also known as a solar panel’s power output rating. Most solar panels are between 250 and 400 watts. So if you purchased panels with 250W of power output, you would need 24 panels to cover all your home’s energy. Or you would need 15 solar panels with power output of 400W.

The other factor involved is solar panel efficiency, or how much sunlight a solar panel can convert into usable electricity. Most solar panels are between 14% and 20% efficient. If you want more potential power output, you’ll want to choose panels with higher efficiency.

Read more about solar panel efficiency and why it matters.

What you need for your appointment: 

We know it sounds complicated, but a qualified Solar Energy Specialist can help you find the type of panel that’s right for your system.

how many solar panels power a home

Factor #5: Your Home Energy Goals

The next factor in your solar system size is the goal of choosing clean solar energy for your home. There are lots of reasons why homeowners are choosing to go solar across the world, and whatever your reason, it’s a great one.

Reducing your monthly electricity bill is a pretty common reason, or being fed up with your utility company. Another great reason is the fact that the price of electricity is continuing to rise every year. Or how about the fact that fossil fuel energy is running out and is horrible for the environment. If your goal is clean, sustainable energy that cuts down on carbon emissions, you’re not alone. More and more every day, legislation, businesses, and homeowners are starting to turn to clean energy.

If one of your goals is to reduce your electricity bill, the size of your system can make a big difference. For some homeowners it can mean thousands of dollars in savings every year. Make sure to discuss your goal and how much of your home’s energy consumption you’re expecting your system to produce.

Another factor to consider is whether your state and utility company offers net metering. You can earn money with your excess energy this way. Whatever energy your panels produce that goes unused you can sell back to the electric company in the form of credits to be applied toward other bills. It can mean smaller energy bills or, in some cases, no bills at all. If this is your goal, make sure to discuss this so it can be part of the decision in the size of your system.

Learn more about net metering.

What you need for your appointment: 

Bring a list of your home’s energy goals when you meet with your Solar Energy Specialist. They can help you understand what this means in terms of how many solar panels are needed for your home.

Factor #6: Solar Battery Storage Options

enphase solar battery 10The amount of solar panels you decide to have installed on your roof is also dependent on whether you’re interested in solar battery storage. Adding a solar battery to your system can mean protection from power outages and clean energy throughout the night. If you’re concerned about the increasing amount of natural disasters and power outages, then a solar panel battery may be right for you.

Read more about power outages and how solar panels can help.

Batteries like Enphase Encharge and Tesla Powerwall will detect grid failures in a matter of seconds, flip on the stored power from your panels and keep your home running over 100 times faster than typical generators — all without the frequent interruptions to appliances.

Read more about Enphase Encharge and Tesla Powerwall.

What you need for your appointment: 

If your goal is protection from power outages, you might consider more solar panels since the excess energy can be stored for future use. Be sure to discuss this goal with your Solar Energy Specialist who can walk you through the reasons a solar battery may be the perfect fit for your home.

Schedule a Free Solar Energy Consultation

There are other factors involved in the decision of the size of your solar array. This can include what incentives are available to you. Get a free consultation and a free quote when you schedule an initial appointment with us. Aside from the number of solar panels, we know you’ll have plenty of other questions about solar power. ADT Solar is happy to provide answers and make your switch to solar clear and easy.

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