Dependent on property attributes, location, energy demand, and more, the number of solar panels needed for every home is different. As you research solar energy for your home, choosing the optimal number of solar panels can help you maximize your installation’s cost efficiency, lower your long-term electricity expenses, and reach your energy goals.
To estimate how many solar panels your home needs in a few simple steps, you can use our system planner.
What determines the best number of solar panels for homes?
Whether you are just getting started or are ready to go solar today, calculating the right number of panels for your installation is a vital step of the process. After your installation, if additional capacity is required to meet your home’s energy needs, solar microinverters make it easy to expand your system one panel at a time.
Home energy consumption
More than anything, calculating how many solar panels your home needs begins with understanding your property’s electricity consumption. Found on utility bills, home electricity consumption is measured in kilowatt-hours (kWh). While energy use varies widely by region and building size, the average American home consumes about 10,500 kWh annually or 875 kWh per month.
As solar energy systems help lower utility bills, most installations are designed to produce the amount of electricity equivalent to a home's annual grid power consumption or slightly more—within the limits of local policies, guidelines, and electrical codes.
Roof space, orientation, and sunlight availability
Photovoltaic (PV) solar panels harness the sun’s energy to generate electricity. Therefore, the number of solar panels needed for your home depends on the amount of sunlight able to reach a system installed on-site. Homes that receive more sunlight, both in annual hours and solar irradiance, can produce more electricity each year than less-sunny properties with the same number of panels installed.
In North America, southern-facing, sloped roofs are ideal for solar energy generation, though any roof surface with direct sunlight exposure may suffice. Solar panels must be installed on a surface that is free of obstructions, and microinverters can help maximize electricity generation for any solar panels that become shaded throughout the day. If there’s not enough room on your roof for your desired number of panels, you may be able to find an alternative solution such as a ground-mounted system or an off-site community solar garden.
Solar panel efficiency and wattage
Getting into the technical aspects of how solar works, solar panels’ efficiency and wattage ratings determine how much electricity they can produce in ideal conditions. Solar equipment capabilities vary by brand and model, though most residential panels have efficiency ratings of around 20% and wattages between 300 watts and 450 watts (W). Besides wattage and efficiency ratings, the number of solar panels you need to power your home may also depend on the performance of your other PV system components, such as your inverters.
Future energy needs
As you plan your solar panel system, consider any anticipated increases in your home’s energy demands. Although it may be possible to add more panels later for extra costs, overcompensating for additional electricity use can help maximize your long-term solar return on investment by avoiding future labor and permitting expenses.
While many things may influence property energy demand, a solar power system can help keep consumption costs low after electrifying gas-powered appliances, adding a new household member, or purchasing and charging an electric vehicle (EV) at home.
How to calculate the number of solar panels your home needs
There are many ways to design your ideal PV energy system, including a solar panel calculator or a consultation with a certified installer. To give you an idea of how these calculations are made, here’s a detailed example of how to find the right number of solar panels, broken down into a few simple steps.
Define project parameters
Let’s say your property consumes 10,500 kWh annually (about 29 kWh daily) and has ample rooftop installation space, which receives five peak sun hours per day, on average.
Determine system capacity
With five peak sun hours and 29 kWh of electricity demand per day, your solar power system should therefore have a 5.8 kW capacity (29 kWh/5 h) in ideal operating conditions.
Calculate panel quantity
To finalize the calculation for the number of solar panels your home needs, simply divide its total capacity by your chosen panel wattage. To reach a system capacity of 5.8 kW, or 5,800 W, you’d need to install about 20 x 300 W panels (5,800 W/300 W = 19.33 panels) or 13 x 450 W panels (5,800 W/450 W = 12.88 panels).
While these steps are meant to be educational, specific project variables can always influence your solar panel system calculations. To find the best home solar system for your property, we recommend weighing several design options and getting estimates from multiple providers before you finalize your installation plans.
Assessing solar panel and battery storage needs
By producing and storing solar electricity onsite, a battery can help you further reduce your dependence on grid power, increase your energy resiliency, and lower your long-term utility costs. While energy storage can increase the total price of a solar installation, batteries may qualify for several solar financial incentives or programs to make the equipment more cost-effective and accessible.
Similar to finding the right number of panels for your home, determining the ideal solar battery capacity for your PV system may depend on your energy goals, budget, and other individual project circumstances.
Key takeaways
In essence, many factors dictate the best number of solar panels for your home, as every installation is based on unique property considerations. To find your ideal solution, we recommend getting to know your energy demands and speaking with multiple professionals for accurate, personalized estimates of your property’s solar power generation and savings potential.
Enphase is here to help you find the best solar panels for your home, with 25 years of warrantied system performance, and an expansive network of trusted installers across the U.S.
Solar panel installation FAQs
Can I install solar panels if my roof has limited space?
Yes, you can install solar panels if you have limited roof space, and the investment may still be worth it to lower your electricity bills. While microinverters are helpful in designing solar panel arrays on irregular roofs, limited space can also be maximized by ensuring you install high-efficiency PV equipment.
How long do solar panels last?
Most modern solar panels include manufacturer warranties that last for 25 years or more, and some systems can last even longer than this. To maximize the lifespan of your solar energy system, regular performance monitoring and routine inspections are recommended.
Is 20 solar panels a lot?
No, 20 solar panels are not really “a lot,” and the amount may be suitable for your home. With enough available installation space, most residential solar power systems consist of 15 to 25 panels, depending on energy demand, home size, and other factors.
Can you put too many solar panels on a home?
Yes, it may be possible to put too many solar panels on your home in such a way that the added equipment costs will not make sense financially. However, if you’re planning to increase your electricity consumption later, like if you purchase an electric vehicle and charge it at home, an oversized system could keep your future energy costs low. When planning an installation, your local building authority or electric utility may also have limits on the amount of solar energy capacity that can be installed on a home in your area.