How Many Solar Panel Installations Are Needed to Power a House?

How Many Solar Panel Installations Are Needed to Power a House? October 12, 2022 | Solar Generators, Solar Panels

After choosing to convert to solar panels, many individuals, companies, and families want to ensure they have the space for solar panels and that it makes financial sense for them. We have helped people determine if solar panels are right for them at Expert Solar, and we are ready to help you. Read more to see how many solar panels would be needed at installation.

Determine How Many Solar Panels You Need

Solar panels are a big initial investment, but they pay for themselves in the long run. To determine how many solar panels you will need to install, you will need to know your annual electricity usage, the wattage of the solar panels installed, the efficiency of the solar panels, and the average amount of daylight per day.

Electric Usage

The amount of electricity you use annually depends on your lifestyle, house size, system efficiencies, and more. For the best estimate of how much electricity you use annually, look at your electricity bill statements. There should be a place where the monthly electricity usage is listed on these statements. This will give you an idea of how many kilowatt-hours (kWh) you use. According to the U.S. Energy Information Administration, the average American household uses approximately 11,000 kWh a year. We will use this average later to calculate the number of solar panels you need.

Solar Panel Wattage

Another contributing factor to the number of solar panels needed at installation is the wattage of the solar panels themselves. The wattage is the amount of energy a solar panel can produce in an hour. When operating efficiently, most solar panels fall between 250 and 400 watts of energy per hour. So, if a solar panel operates on 12 hours of sunlight a day and typically puts out 300 watts an hour, that solar panel would produce 3600 watts per day. That is equivalent to 3.6 kWh per day ([300*12] / 1000). Of course, this number fluctuates daily depending on the amount of sunlight and other factors that can affect the efficiency of your solar panel.

Efficiency Ratio

The efficiency ratio of a solar panel is the amount of energy it can produce (total kWh of the solar panels) versus the amount of energy it actually produces. Ideally, a solar panel would have a 1:1 ratio in efficiency—meaning that any energy captured is used towards electricity. However, this efficiency ratio can vary widely depending on the amount of sunlight the system receives, weather patterns, etc.

In some areas, the efficiency ratio can be upwards of 1.5 (10 kW system producing 15kWh), such as tropical locations where sunlight is constant. Solar panels can be even more efficient in these areas, and storing excess energy in a battery can be beneficial. Similarly, in an area that is consistently cloudy, overcast, or rainy, the energy efficiency ratio can get to 1.2. Most solar panel installation companies will have a good understanding of the average energy efficiency of solar panels in your area.

Hours of Sunlight

The efficiency of your solar panels is predominantly determined by the amount of sunlight your home receives daily. If you live in an area that is cloudy, rainy, snows or doesn’t receive direct sunlight, you will likely need more panels. In general, solar panel installation companies recommend you install 25% more solar panels to ensure you can power the entirety of your home. Similarly, if you live in an area with a bunch of sunlight, you can usually stick to the calculated number of solar panels. In your case, you may even need solar panels with battery storage. In some places, energy companies will pay you for the stored energy you produce—getting an even more significant return on your investment.

Calculate the Number of Solar Panels You Need

The formula for determining the number of solar panels you need to install is relatively simple. It is:

Solar Panel Number = Annual Electricity Usage / The Efficiency Ratio / Panel Wattage

Now, let’s use the average household usage (11,000 kWh), an efficiency ratio of 1.2, and a panel wattage of 300 W.

Solar Panel Number = (11,000)/(1.2)/(300)

Solar Panel Number = 30.55

Now, this would be the base number to produce the electricity used on an average basis. But, if we want to ensure that you have enough electricity, that would require us to use 25% more than that number. This means you would need 30-37 solar panels to power your home correctly.

Solar Panel Installations in Virginia Beach

Overall, no matter how many solar panels you need to install, it is a sound investment choice for your future. Expert Solar installs home solar panels in Virginia Beach and have helped several individuals convert to this renewable energy source. Not only can your home become greener and more efficient, but you can also discover the freedom of living off of grid energy.

Are you ready to take the next step? Our solar panel experts can help you determine how many solar panels you need and guide you through the process of applying for the Federal Solar Tax Credit.

Call our Expert Solar today at 757-988-7777.