Calculating how much area you need for your solar panel installation
Home solar panels are a great way to gain energy independence and reduce your utility bills and carbon footprint. However, they also require a significant amount of space. If you want to go solar, it’s critical to determine how much area is needed for your solar panels when planning an installation.
To help you decide if your property is suitable for solar, this guide outlines roof space requirements and breaks down how to calculate the area needed for your home solar panel installation.
Understanding home solar power system installations
Over the past 20 years, millions of Americans have installed rooftop solar panels to harness the sun’s energy, generate electricity, and lower their ongoing utility power expenses. While many kinds of solar technology are available and in development today, most home solar panels are rigid monocrystalline or polycrystalline devices that can efficiently generate significant amounts of electricity with minimal roof space required.
A typical home solar panel is about 3 feet wide by 5.5 feet long, occupying an area of roughly 17.5 square feet (sq ft). On average, the amount of required roof space for a set of home solar panels is between 300 sq ft and 500 sq ft total.
When looking into a system for your home, the amount of required roof space will be dictated by the number of solar panels you plan to install. However, limited roof space can also limit the potential size of your installation. While the average homeowner installs between 16 and 25 panels nationwide, the size of your system may depend on the following factors:
Your home’s energy demand
Most home solar panel systems are designed to produce enough annual electricity to meet the property’s approximate energy demand.
Your property’s solar potential
The solar potential for your home depends on several variables, including the average number of daily sunlight hours in your area, your property’s shade conditions, and the direction and angle of your roof.
Available installation space
Roof space for solar panels must be free of obstructions like chimneys, vents, and dormers, which can limit the potential size of your installation. To mitigate shade and install panels across various surfaces, microinverters can enable you to maximize your available roof space.
Your solar panel’s attributes
A solar panel’s potential electricity output is determined by its wattage and efficiency, which will influence the quantity necessary to reach your energy goals.
As the optimal number of solar panels for your home is dependent on many individual circumstances, we recommend speaking with a professional installer to help design your system. Or, to get started right away, you can also use our home solar panel calculation tool for a quick and accurate system design unique to your residential property, energy demands, and personal preferences.
5 steps to calculate the area needed for your solar panel installation
Calculating the square footage needed for your solar installation depends on many unique project factors, which include your roof’s attributes, where you live, and the specific panels you choose to install. For a quick idea of how much roof space you’ll need, here are five steps you can take when calculating area for solar panels on your property.
Step 1: Determine your daily electricity usage
Going solar starts with understanding your home’s electricity usage. Measured in kilowatt-hours (kWh), your annual electricity consumption can be found on your utility bills. If you divide this number by 365, you can calculate your average daily electricity usage. In the U.S., the average home consumes about 30 kWh of grid electricity per day.
Step 2: Identify the average peak sun hours in your area
Solar panels can generate electricity at the highest efficiencies during peak sun hours, which are usually in the late morning and afternoon. Across the U.S., the average property receives between 4 and 5 peak sun hours per day—though this varies greatly by region and season. You can estimate your property’s daily solar radiation, and expected system output, using the PVWatts® calculator from the National Renewable Energy Laboratory.
Step 3: Calculate your ideal solar power capacity
By dividing your average daily electricity use by your property's peak sun hours (PSH), you can estimate your approximate solar energy system size. If your home consumes 30 kWh of electricity and receives 4.25 PSH per day, this will equal a solar system capacity of approximately 7 kilowatts (kW). To account for energy losses during inclement weather, this number can be multiplied by 1.2, which translates to an ideal system capacity of about 8.5 kW or 8,500 watts (W).
Step 4: Choose the number of panels you’ll install
To calculate the number of solar panels you need, divide your system’s total capacity by the wattage of each panel. As the average home solar panel is about 400 W, an 8.5 kW system would consist of approximately 21.25 panels. Rounding up, a 22-panel installation may be best.
Step 5: Estimate your required roof space for solar
Finally, multiply the number of solar panels by the square footage of each module. The average residential solar panel size is about 17.5 sq ft—though it’s good to overestimate the area required as some installation space is necessary between the panels and rows.
When installing 22 panels like in our example, and each panel takes up about 18 sq ft, your system would require approximately 396 sq ft of roof space. If you use microinverters, this could be spread across multiple roof surfaces without compromising total system performance.
Additional influences when calculating roof space for solar panels
While the scenario laid out above is meant to illustrate an example, every solar power system installation is unique with many other considerations that could affect the area required for your panels.
Most importantly, the regulations of your local building authority will dictate where solar panels can be installed on your roof or property. While codes and requirements vary across the country, many city and county governments maintain solar setback rules. A “setback” dictates how far your panels must be placed from your roof’s ridges or edges to allow for walkable space, which can limit your home’s total available installation space.
Lastly, shaded solar panels—due to trees, neighboring buildings, or other obstructions—cannot generate electricity as efficiently as those exposed to direct sunlight. If sections of your roof receive partial sunlight throughout the day, adding extra panels can help increase your total solar power generation capacity, just as installing microinverters can help maximize your system’s performance.
Connect with an expert to install solar
If you believe there may be enough usable space on your roof or property for solar panels, reaching out to a professional is the best way to design and install a system optimized for your home. By contacting an Enphase-certified installer in your area, you can connect with a local expert and access high quality equipment and industry-leading warranty coverage for your solar panel system.
How much area is needed for a solar panel installation FAQs
Do solar panels need a lot of space?
Relatively speaking, solar panels do not need a lot of space to generate substantial amounts of electricity when exposed to direct sunlight daily. Residential solar panels usually take up areas of less than 20 sq ft each, and microinverters can help you add efficient, energy-generating capacity across all the usable installation space on your roof or property.
How much land do solar panels need?
Ground-mounted panels are a great large-scale solar solution that can sometimes be used in residential circumstances when enough installation space is available. The amount of land needed for solar panels depends on your system size, though generally at least 300 sq ft is required. In some areas, a security fence must be installed around ground-mounted solar panels, which can increase your project’s total footprint. Install costs can also sometimes be prohibitive for ground-mounted systems, as they usually incur more project expenses than rooftop panels.
What is gap spacing for solar panels?
Gap spacing refers to the small spaces between your solar panels necessary to securely install your system to rooftop solar mounts. Although these spaces are often less than half of an inch, it’s important to consider gap spacing when going solar to ensure the accuracy and permit approval of your system design.
