How many solar panels do I need?
Updated
The amount of solar panels your home needs depends on the amount of energy your home needs, as well as the efficiency of your panels.
A typical American home will need 14-36 solar panels to cover their power bill and at least 227 square feet of rooftop space to accommodate the solar panels.
The amount of energy that solar panels can absorb, and then produce, is measured in kilowatts (kW). The amount of energy your home uses over a certain timeframe, say a month, is measured in kilowatt hours (kWh).
You need to know how many kWhs your home uses to determine the amount of kWs your solar panels need to produce to offset your use. You can also use this information to determine the number of panels your home will need.
In this blog, we will review the factors that solar installers take into account when recommending how many solar panels you need for your home.
On this page:
- How many solar panels needed for a typical house?
- How to calculate number of panels for your home
- How many solar panels needed for average electricity usage?
- How many panels will fit on my roof?
How many solar panels are needed to power a house?
Interestingly, your home size does not actually determine the amount of solar panels you need; a bigger home does not equal more energy consumption.
To really understand how many solar panels your solar energy system needs, you need to determine:
- The amount of energy your home uses: Look at monthly kWh used on your electric bill
- The direction of your roof: Southern-facing roofs receive more sunlight in the northern hemisphere
- The average amount of sunlight in your local area: Put more simply, the southwest gets the most sun in the United States, versus the northeast which gets some sun but with more rain and snow mixed in
- The amount of wattage, or energy, the solar panel you purchase can produce: Solar installers can help you determine your options
You can also use the solar panel calculator immediately below to give you an exact number of solar panels by entering your address and the average amount of your monthly electricity bill. This solar calculator has solar production data from all weather stations around the country, and it is also able to show you the cost and savings you will get from going solar.
How do I find the exact amount of solar panels I need for my home?
The best way to determine the exact amount of solar panels your home needs is by working with solar installers. They will be able to accurately calculate the type and amount of solar panels that will work best for your home.
Solar panels are a great way to reduce or cancel out your power bill and take advantage of other money-saving benefits like net metering and federal incentives. Each home is unique but they can all be powered by solar.
How many solar panels do I need for 1,000 kWh per month?
According to the U.S. Energy Information Administration, in 2018 the average monthly electricity consumption for a home in the United States was 914 kWh per month, or about 30.5 kWh per day and 11,000 kWh per year.
But every home is unique and could use more or less power than the average home. Other factors can determine solar panel effectiveness such as roof direction, shade, or the climate where you live.
The solar system size your home needs will depend on your electricity consumption and the climate of your region. You can find out how many solar panels your home needs by using our solar calculator.
To help you better estimate the potential size solar array your home will need, the below chart can provide a little more clarity.
| Average annual electricity usage for all homes | Solar system size needed to produce average electricity | Amount of solar panels needed | |
|---|---|---|---|
| West - California | 6,522 kWh | 4 kW | 14 |
| Northeast - New Jersey | 8,280 kWh | 7 kW | 25 |
| Midwest - Illinois | 8,929 kWh | 7 kW | 25 |
| South - Texas | 14,112 kWh | 10 kW | 36 |
| *280 watt solar panels |
This table breaks down the average annual electricity usage for each region in the US. The four states listed, California, New Jersey, Illinois, and Texas offer some of the best solar incentives for their respective regions.
The average energy use varies widely per region for a few reasons. For example, the northeast is more urban, with many multi-family homes versus the south with more single-family homes.
We listed the solar system size that would be needed in each region to offset that particular region’s average electricity usage. So for example, to cover the energy needs of a typical home in California, you would need a 4kW solar power system to generate 6,522 kWhs of electricity.
The numbers vary mostly because of the climate of each region. For example, you need a smaller system in southern California because the sun shines all year long. But you need a slightly larger system in New Jersey because there are more cloudy days and winters to consider.
Last, we listed the amount of 280-watt - a middle-ground panel wattage amount - solar panels that would be needed to produce the necessary electricity.
However, your home’s energy use could be totally different than the average. You can use our use our solar panels cost calculator to work out how much the number of solar panels quoted in the table above for your state will cost. Although before you do this, it is worth taking note of how the size of your home and your electricity usage varies from the norm as this will ultimately determine the number of solar panels you need.
How much roof space do I need for solar panels?
Even if you know the amount of solar panels you need, it won’t help if your roof can’t fit them. In the chart below, we break down the square feet your rooftop would need for a 5kW, 10kW, and 15kW system.
| System size (kW) | Square footage needed for low efficiency (16%) | Square footage needed for medium efficiency (18%) | Square footage needed for high efficiency (22%) |
|---|---|---|---|
| 5 kW | 313 | 278 | 227 |
| 10 kW | 625 | 556 | 455 |
| 15 kW | 938 | 833 | 682 |
We calculated the amount of square footage needed based on the potential efficiency of panels you would purchase. We used the 16%, 18% and 22% for low, medium and high efficiency solar panels. Most solar panels range in efficiency from 16%-20%, so 22% would be exceptional.
Solar panel efficiency essentially means that your solar panel is either okay, good, or great at absorbing sunlight for energy production. Higher efficiency panels means you need less of them, and in turn, less square footage of roof space in order to produce energy.
Once you determine the kW size of the solar panel system you need by using the chart above, take a look at the amount of space a low, medium or high efficiency panel will take up on your roof. If you have extra space to spare, it might make sense to buy lower efficiency panels since they are cheaper than higher efficiency and can produce the same amount of electricity.
It is more important to have a panel that produces more watts of energy versus a more efficient panel, but in order to use the smallest amount of panels on your roof, you would need the most efficient, highest-wattage producing panel. We recommend Panasonic, but many brands offer similar quality for a lower cost.
Determining which efficiency-level solar panel makes sense for your home will depend on the amount of space you have. In order to make sure your roof has enough space, find out here.
Ultimately, most homes should be able to accommodate solar panels on their roofs. Working with a professional contractor can help you determine the best solar system for your energy needs. Be sure to check out local installer reviews.
Key takeaways
- The average American home needs 14-36 solar panels to cover their electricity bill.
- If you live in a sunnier state, less solar panels are needed to generate the electricity your home needs.
- More efficient solar panels means less solar panels are needed.
- High efficiency panels are necessary when installing solar panels on a small roof.
Author: Ana Almerini | Web Content Specialist
Ana is a web content specialist at SolarReviews. She has 5 years of marketing experience blended with 2 years of experience in climate communications and holds a master of arts degree in climate and society from Columbia University. Ana frequently volunteers for environmental causes ranging from oyster reef restoration in NJ to expanding bike sharing in Naples, Italy.