Solar System Size: How Many Panels Do I Need?

July 30 2020

Solar system size plays a big role in ensuring that your panels produce enough energy to cover your usage. If you’re considering switching to solar, you’ve probably asked yourself, “How many solar panels do I need?”

Solar installer figuring out how many solar panels do I need

The answer depends on how much energy you use, and how low you want your electricity bill to be. For many homeowners, an electricity bill of $0 is the ultimate goal. In this case, they need to choose a solar system size that will cover all their usage.

The solar system size you select for your home will also depend on solar panel efficiency and solar panel size.

We’ll break down each of these factors and introduce a solar panel calculator to help you decide how many solar panels you need. Keep reading to learn more about solar system sizes and how to get the perfect solar installation for your home.

Solar Panel Efficiency

Solar panel efficiency refers to the percentage of energy from the sun that actually gets converted into electricity. The efficiency of solar panels is constantly increasing. Today, the most advanced solar cells can convert 25% of the energy that hits them, compared to 6% in 1955.

The typical residential solar system has a solar panel efficiency of 19%. This number is used to determine a panel’s “power rating”. This rating tells us how many watts a solar panel is rated to produce.

Most residential panels are rated to produce anywhere from 285 to 360 watts. A higher number means the panels are more effective at producing energy. The power rating represents output under ideal conditions. Although most panels will rarely operate in perfect conditions, these ratings are a good way to compare panels.

Solar panel efficiency is important because it affects the amount of electricity produced by your system. Higher efficiency allows you to invest in fewer panels.

Solar Panel Size

Solar panel size is another important factor in determining your home’s overall solar system size. The larger each individual panel, the larger your system will be.

Most residential solar panels are about 65 inches high by 39 inches wide. These panels are made up of 60 individual solar cells, aligned in 6 columns with 10 cells in each column. This is the most popular type of panel for solar panel installation.

Other solar panels are made up of 72 cells. These panels have the same number of columns but with 12 cells in each column. These panels are longer than 60-cell panels.

When panels have more cells working in conjunction with one another, they’re able to produce more power. Keep in mind, however, that your specific roof space will play a huge role in determining your options.

Consider panel size when deciding on solar system size.

Solar Panel Calculator

The amount of electricity your system will produce also depends on the amount of sunlight your panels receive. Determining solar panel energy production will help you answer the ultimate question: “How many solar panels do I need?”

Use this solar panel calculator to estimate each panel’s energy output per day:

STC Rating x Hours of Sun per Day = Watt-hours (Wh) produced per day

A panel’s STC rating indicates how much power it will produce in ideal conditions. This number is located on the back of the panel.

The average roof in the United States receives about 4 full hours of usable sun each day. Of course, the sun shines longer than 4 hours, but “full hours” combine all parts of the day with partial sunlight into peak sun hours.

Using the solar panel calculator, a panel with an STC rating of 250 watts will produce 1,000 Wh, or 1kWh, per day. To put this into perspective, a 100 watt light bulb uses 0.1 kilowatts each hour. The average household consumes 28.9 kWh per day. Based on this calculation, the average homeowner would need around 29 solar panels with an STC rating of 250 to cover 100% of energy usage.

Factor your personal energy consumption into the equation. If you commute to an office all day or live alone, your usage will be lower.

Brick home with large solar panel installation

Solar Panel Installation

Now that you have an idea of the solar system size you need, it’s time to find an installer. A common mistake homeowners make when switching to solar is trying to install panels by themselves. Finding a solar panel installation company is critical to the long-term success of your system.

Save time and money by choosing a solar installer who can get the job done efficiently. Plus, a solar panel installer will be able to point you in the right direction when it comes to selecting panels and sizing. If you’re still asking yourself, “How many solar panels do I need?”, an installer can help.

You’ll also want to invest in solar panel installation from a company that knows the local and state tax incentives that are available. Industry-leaders will be able to save you money on solar. Greenlife Solar partners with these leaders to offer you a variety of choices. Get transparent information on each installer before you commit.

Use Greenlife Solar to get started with solar panel installation. We offer a free online service to help you compare pricing from solar installers near you. Find the best system for your budget and home with Greenlife Solar.

Get Pricing on Solar Panel Installers Near You.