Solar panels can help a household save money on electricity and increase a home’s value. But the right number of solar panels is required to achieve the maximum economic benefit. Here’s how to calculate the number of panels you’ll need:

How much sun exposure does your home experience throughout the year?

The amount of sunlight your home receives each day will affect the amount of energy the solar panels are able to produce. For areas with less peak sunlight, more panels may be required to produce enough electricity to run a household, while areas with mild winters and more peak sunlight will require fewer panels. The Renewable Resource Data Center can provide sunlight information for most major cities.

How much usable space do you have on your roof?

Solar panels range in performance, generating different wattage for a given surface area. Wattage can range from around 150W per panel to over 350W. A home with little usable roof space might require the highest-performing panels to generate enough electricity. Houses with larger roofs may be able to use a larger number of panels with lower wattage specifications.

How much energy does your home currently use?

In order to know how much energy you’ll require from solar panels, you’ll need to look at past utility bills to see how much your home currently uses. The monthly bill should include the wattage used as “kWh” (kilowatt-hours). You can find your average monthly usage by adding several previous months of energy usage and dividing the sum by the number of months you are referencing. (It’s best to include a full year of usage, to account for seasonal differences in energy use.) Next, calculate your average daily usage and average hourly usage. Once you have an hourly energy requirement, multiply that by the number of peak sunlight hours in your area. Divide that number by the wattage provided by the panels you are planning on using.

(Hourly Energy Requirement = number of panels required

Because solar panels don’t operate at full capacity all the time due to weather conditions, building an extra 25% into the energy requirement will help ensure that your system generates enough electricity to run the home.

While it’s important to understand what goes into these calculations, we understand it can be confusing. Our solar energy experts are available to assist you in every step of planning and installation. For more information about installing a solar power system for your home or business, call TerraSol Energies at 888-873-9995. We install solar systems in Pennsylvania, New Jersey and Delaware.