How many Solar Panels Do I Need?

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Last Updated on March 18, 2024 by admin

How many Solar Panels Do I Need? Answer to a Constant Question

A guide to understanding how many solar panels are needed to eliminate or reduce your electric bill.In our long history, we have installed solar panels on thousands of homes and businesses. We have found that people have two main reasons for installing solar. The first and most significant reason is to get rid of or reduce electric bills. The second reason is to reduce their environmental impact and the use of fossil fuels. One of the most consistent questions from solar is always: “How many solar panels do I need?

How many Solar panels?

The quantity of solar panels you need and how many you should install depends on many unique elements. These include the amount of energy consumed by a house and its location. Also, the size and angle of the roof are factors. We’ll answer all your questions in this blog including what elements go into that calculation.

What factors determine your solar panel needs?

No home is the same so the answer varies on your individual needs. However, certain factors will always help you understand how many solar panels you’ll need for your home. These are key considerations:


Understanding how much energy you want to generate with solar is the first and most important thing to consider when deciding how many solar panels you need. The more energy you use, the more solar power you’ll need to replace all of your electric consumption. However, you may only opt to replace some of your electric use with solar power depending on other factors.

System Wattage:

 The second critical factor is the wattage of a solar system. The more watts, the more a solar installation will produce. Also, solar panels come in various wattages. Panels with higher wattages produce more power, meaning you need less roof space for higher watt solar panels, but they often cost more.

factors for panel needs
Production Ratio:

This helps you figure out the number of panels you need based on your energy needs and wattage need. It’s the ratio of the expected energy output of a system over time in kilowatt hours (kWh) compared to the wattage of the system. This is something a solar professional is best suited to explaining.

Roof aspect and size:

The best roofs for solar panels are those with adequate space for solar that face toward the sun think south or southwest. Angles around 30 degrees are ideal for flush mounting a solar array to a roof in most of the US.

Energy Goals:

Do you want to replace all or some of your electric use with solar power? You may start with a small system and choose to grow it over time or install a large system to meet all your needs.

How many solar panels do you need?

If you’re thinking about how many solar panels you will require, keep these things in mind:

  • What’s your average monthly energy consumption in kilowatt-hours (kWh)? This will give you an idea of your current energy use and how much you could replace with solar power.

  • What’s the weather like where you live? The sunlight in your area affects how much energy your solar panels can produce.

  • How efficient are the solar panels you’re considering? They vary in efficiency.

  • How much area on your roof can support solar power? The physical size of your roof can impact how many watts of solar panels you can install.

How do you calculate how many solar panels to install?

When planning a solar panel installation there are a number of calculations you can make to begin planning how many solar panels you’ll need. First thing is to consider your annual energy usage and how much you want to replace with solar power. Then you’ll need to learn what the solar production ratio is in your area based on the amount of kilowatt hours a system should produce per watt and divide that by your energy usage. Finally divide that by the amount of wattage of the solar panels you are considering purchasing and you’ll come up with how many panels you should need to replace your electric usage.

Or: Annual energy usage/production ratio/panel wattage=how many panels you need.

Sounds complicated, but we make it easy for you with  . It’s the simplest solution for understanding how much clean energy you can produce with the sun.

How many peak sun hours does your home receive?

Your home solar system’s energy output will depend on when the sun shines the brightest in your area. In the United States, the average daily peak sun hours vary. It’s 5.75 hours in the Southwest and fewer than 4 hours in the northern regions. If you live in Phoenix, you can expect more peak sunlight hours than in Seattle. That implies a house in Seattle would need more panels to generate the same amount of energy as a system in Phoenix. It doesn’t mean a Seattle homeowner shouldn’t go solar.


What’s the quickest way to calculate your solar panel needs?

The quickest way to calculate your solar panel needs is by using our solar calculator. Otherwise, you’ll have to conduct some research and do the above math in an attempt to guess how many solar panels you need to replace all or part of your electric use. The calculator also will estimate the cost of a solar panel installation based on your location and help you decide if solar power is cost-effective for your home.

Can 10kW of solar run a house?

Yes. In the US a 10 kW solar system is often more than enough to power a home. The typical US family uses 30 kWh of electricity each day. Depending on sun exposure, you would need a 5 kW to 8.5 kW solar systems to offset 100% of that amount and most US residential solar systems are a bit over 6kW in size.

How much space is required for solar PV panels?

The average residential solar panel is a little over 5 feet long and a little over 3 feet wide or about 17.6 square feet. A typical system is between 21 and 34 panels in size. As such, a normal solar system will need between 369 and 598 square feet of roof area.

If you have limited roof space, you may need higher-wattage, high-efficiency panels. This will help you meet your energy needs with fewer panels. Based on the size of your roof a solar installer, like SolarSME, can help you identify which sort of solar panels are ideal for you.

Space required

Do you need more solar panels to live off grid?

Generally yes. If you’re planning on living off-grid and only using solar power and a battery system to provide your electricity you’ll want to make sure the system can provide enough power to meet your needs even in the winter when solar panels produce less energy. For such systems it’s recommended you talk with solar experts to help you understand how much more energy you’ll need to be able to save.

Is your home suitable for solar power?

Most homes have enough roof space and are oriented in such a way that solar power can be incorporated and provide at least a substantial amount of your energy needs. The number of panels you will need varies on your goals. Several factors will impact your choices and the system’s ability to generate some or all of your needs. These include roof size, orientation, whether you want to replace some or all of your energy use and whether you want to include a local energy storage system, like a battery.

SolarSME will help you determine the number of solar panels you need to fulfill your home needs. Our energy experts can assist you with understanding what you’ll need to go solar and what to expect from your system.


In the end, solar panels are one of the best options to free you from rising energy bills and reduce your use of fossil fuels. While you can make all the calculations yourself to figure out how many solar you need, a much easier option is to use a cost calculator or consult with solar panel experts like SolarSME.

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