Why does solar panel efficiency matter?

When you’re going solar, you probably want to know how to get the most from your solar energy system. How do you do that? You’ve got to understand solar panel efficiency.

Not all solar panels are the same. They come in different sizes and different finishes. But efficiency might be the most important factor. Efficiency is the measure of how well solar panels perform.

The more efficient solar panels are, the fewer panels you’ll need to power your home. Solar panels with a high-efficiency rating allow homeowners to install a smaller array, which is especially useful for homeowners with smaller roofs.

Still have questions? Fortunately, we have the answers to common questions about solar panel efficiency, including:

  1. What is solar panel efficiency?
  2. What factors affect efficiency?
  3. How efficient is the average solar panel?
  4. Why should you consider your roof’s peak amount of sunshine?
  5. What can you do to improve the efficiency of your solar panels?
  6. Do solar panels become less efficient over time?
  7. Which solar panels are most efficient?

Let’s break it down.

1. What is Solar Panel Efficiency?

Solar panel efficiency measures how much sunlight a solar panel converts into usable electric currents. For example, when the sun shines directly on a solar panel with a 20% efficiency rating, the panel converts 20% of the sun’s energy to electricity. A solar panel with 20% efficiency will produce more electricity than a solar panel with 15% efficiency, even if they receive the same amount of sunlight.

In terms of efficiency, a higher rating is always better.

2. What Factors Affect Solar Panel Efficiency?

We know that solar panel efficiency is the measure of how much electricity solar panels produce from sunlight. But why are some panels more efficient than others? There are a couple of factors that can make one model more efficient than another. Let’s take a look.

  • Cell Composition ― Photovoltaic (PV) cells are composed of silicon, a material that absorbs the sunlight which shines on it. The sun’s rays hit electrons in the silicon and give them energy, causing the electrons to move.
  • Electrical configuration ― A PV cell is designed so that the electrons all go in the same direction, creating an electrical current. Together with the cell’s voltage (which originates from the cell’s built-in electric fields), the current determines the wattage produced by the solar cell.
  • Surrounding components ― Since silicon is a reflective material, an anti-reflective coating is essential for improving the amount of sunlight the cell absorbs. Once they have enclosed each cell in a protective glass cover plate, solar panel manufacturers connect individual cells to produce effective current and voltage levels.

3. How Efficient is the Average Solar Panel?

As of October 2022, the most efficient solar panels on the market are approximately 23% efficient. If that seems low, you might want to check under your car’s hood.

According to fueleconomy.gov, the average gasoline-powered car is between 12% and 30% efficient. And you have to pay for that fuel. The sunlight hitting your solar array, on the other hand, is free of charge.

4. Why Should You Account For Your Roof’s Peak Amount of Sunshine?

Peak sunlight refers to how many hours of sunshine your roof gets each day. The amount of peak sunlight received varies from home to home. Factors that influence peak sunlight include:

  • Geographical location within the U.S.
  • The direction the roof faces
  • Shade from trees and other structures

You can get a better idea of how much sunlight your roof gets, based on your home’s geographical location, by referring to this resource from the National Renewable Energy Laboratory.

In general, the less peak sunlight your home receives, the more efficient your solar panels will need to be. This is especially true if your roof is on the small side.

If you still need help calculating your home’s amount of peak sun hours, one of our Solar Energy Specialists would be happy to assist!

5. How Can You Improve the Efficiency of Your Solar Panels?

While it might not make a huge difference right away, there are actions you can take to increase how much sunlight your array converts into usable electricity. These small measures can add up over time and make a big impact in the long run.

Actions that can improve the efficiency of your solar array include:

Getting your panels professionally cleaned

As dust and dirt accumulate on your panels, less sunlight reaches the solar cells. Less sunlight means less output. If you get a lot of rain at your home, you might need to clean them a little less frequently.

Removing overhanging branches

Solar panels perform at their optimum level when they’re exposed to direct sunlight. Most of us love trees, so you might not want to cut one down for better solar efficiency. But removing branches that block the sun could give you a big energy boost.

Considering a solar battery

A solar battery allows you to store excess solar energy your array generates for later use. Technically, a solar battery doesn’t make your solar panels more efficient, but using stored power at night, on days with minimal sunlight or during power outages can make your entire system more efficient.

6. Do Solar Panels Become Less Efficient Over Time?

Not exactly ― but their performance does degrade as they age. And as this happens, your solar array will produce a little less solar power. Now, keep in mind that the average solar panel degradation rate is only about 0.5% per year. Some panels will degrade more slowly, while others will degrade faster.

Let’s use a 6 kilowatt (kW) solar power system located on a home in Massachusetts as an example. You could expect this system to generate 7,771 kilowatt hours (kWh) in the first year. If the panels degrade at 0.5% per year, the system will generate around 7,736 in the second year. Each year it will produce 30 to 40 kWh less than the previous year. At the end of the panel’s 25-year warranty, the system will produce approximately 6,890 kilowatt-hours per year.

7. Which solar panels are most efficient?

The majority of residential solar panels on the market today fall into one of three categories:

Yes, efficiency is an important property when it comes to choosing solar panels. But you shouldn’t decide based on efficiency rating alone. Additional factors like durability, aesthetics and cost are important to consider.

Still Uncertain About Solar Panel Efficiency?

If you still have questions about solar panel efficiency, don’t worry ― one of our Solar Energy Specialists would love to help! We can help guide you towards the array that will fit your home best.

When you choose a solar power system from ADT Solar, you can rest assured you’re in good hands. Leveraging more than 147 years of experience, we help protect customers with home security solutions, keep them connected with smart home solutions and empower them with solar energy for their homes.

From the placement of solar panels on your roof, to the quality of the panels themselves, we’ll go the distance to maximize the efficiency of your solar array.

As part of our unwavering dedication to customer service, ADT Solar offers warranties and guarantees that are among the best in the industry. The high-quality arrays we install are designed to last for decades. For that reason, we are confident about standing behind our products with the following:

  • 25-year labor guarantee
  • 25-year power production guarantee
  • 25-year Enphase microinverters guarantee

Learn more about how efficient solar panels can help you save on your electricity bill. Get started by reaching out to us today!

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