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What Do Solar Panel Efficiency Ratings Mean for Homeowners?
What do solar panels efficiency ratings mean for homeowners

What Do Solar Panel Efficiency Ratings Mean for Homeowners?

Published on:
March 7, 2024

Solar technology has gotten much better at making solar panels efficient. Five years ago, the typical solar panel was about 19% efficient, which could turn 19% of sunlight into electricity. 

The average efficiency in 2024 is around 21%-23%. It means there is 10%-12% more electricity per panel as we speak. 

But what do solar panel efficiency ratings mean for homeowners? This is what we will try to understand today! Also, get some ideas about topics related to it.  

Different solar panels have different efficiency levels. Usually, the ones with higher efficiency ratings cost more.  

For example, SunPower and Canadian Solar are the most efficient panels in the Australian market. But they’re also the most expensive, with an efficiency of 22.8%.  

Other brands like REC, Jinko Solar, and Q CELLS also have panels with efficiency above 22%.

What Does Solar Panels Efficiency Mean?

Solar panels are made up of modules or photovoltaic (PV) cells. The efficiency of a PV cell tells us how much light energy it can turn into electricity.  

Another way to think about it is how well a panel can grab energy from light particles called photons. When sunlight hits a solar panel, it sets free some electrons, which start moving and make electricity. 

For instance, a 19% efficiency solar panel can transform 19% of sunlight into useful electricity. Most solar panels you can buy have an efficiency below 23%.  

These usually range from 15% to 20%. SunPower and Canadian Solar are leading the industry right now with panels that have 22.8% efficiency.

Module Efficiency vs. System Efficiency

One solar panel’s efficiency differs from the efficiency of the whole solar system when it’s set up. Just like electricity can get lost in wires, some energy made by solar panels gets lost, too.  

Solar panel systems need inverters to change the type of electricity the panels make so they can power your appliances at home. The best inverters can change most of the electricity, but there’s still a little loss during this process. 

Because some energy gets lost in wires and changing electricity, the efficiency of one solar panel will always be higher than the entire system’s efficiency.  

For example, if you have solar panels that are 22% efficient, the whole system might work at about 19% efficiency. 

These numbers might sound small, but remember, solar cells use sunlight, which is free and doesn’t cause pollution. Fossil fuel power plants can be around 60% efficient but require fuel, which costs money and creates pollution.

Why Solar Panel Efficiency is Important?

solar energy

High-efficiency solar panels may cost more initially, but they have many benefits. The money you save on electricity bills from using solar power can help compensate for the initial higher cost over time.  

Here are some reasons why high-efficiency solar panels are a good idea:

Better Use of Space:

High-efficiency panels convert sunlight into electricity to use your roof space better. For example, if you have panels that are 20% efficient instead of 10%.  

They can make twice as much electricity in the same area. It means you need fewer panels to make the same amount of power. 

Energy Savings:

Certain types of panels, like monocrystalline ones, are more efficient and produce more power than others of the same size.  

For instance, a 370-watt monocrystalline panel can make more electricity than a 300-watt polycrystalline one. This means you can save more money on electricity bills with fewer panels. 

Less Impact from Heat:

When solar panels get hot, they lose a bit of their power. This is temporary but can add up over time if it happens a lot. Monocrystalline panels are better at handling heat than polycrystalline ones, so they work well even in hot places. 

Qualify for More Incentives:

Some programs give you back money based on how much power your solar system can produce. Since high-efficiency panels can make more power, they can qualify for more money back.  

For example, the federal solar tax credit lets you get back some of the money you spent on your solar system as a tax credit. If you use monocrystalline panels, which cost more but make more power, you might get more money back. 

In short, even though high-efficiency solar panels may cost more upfront, they can save you money in the long run and make better use of your space.

How Do You Make Solar Panels More Efficient?

There are many ways to ensure your solar panels work as well as possible.

Get a Professional to Install Them

Professionals know how to set up your solar panels correctly. If they’re not set up right, they might not last as long or make as much electricity. Most companies offer a 25-year warranty, but you’ll only get it if a professional installs your panels.  

If you try to install them yourself, you might lose the warranty. A warranty can help fix broken panels for free, keeping your solar system efficient.

Keep Them Clean

Solar panels need sunlight to make electricity. If they get covered in dust or dirt, they won’t work as well. It’s a good idea to clean them at least twice a year. Some companies are making coatings for panels that stop dust from building up, but they’re still new.

Clean Them Safely

It’s important to clean your panels the right way. Don’t use anything rough that might scratch them. Soft brushes and squeegees are best.  

You can also hose them down, but not when they’re hot, or they might crack. If you damage your panels while cleaning them, your warranty might not cover it.

Keep Them Out of the Shade

Shade can make your panels less efficient. If one panel part is shaded, the whole panel might need to be revised.  

So it’s best to put your panels where they’ll get lots of sunlight. It can be tricky because shadows change throughout the day and year. A professional installer can help find the best spot for your panels using special software.

Choose the Right Panels

Even if you do everything else right, choosing the type of panels is essential. A panel that’s 22% efficient will make more electricity than one that’s only 15% efficient, even if they’re both cleaned regularly. Talk to a professional to determine which panels are best for your needs. 

What Are the Best Solar Panels?

As we’ve talked about before, monocrystalline panels are usually the best when it comes to efficiency. Polycrystalline panels are in the middle, and thin-film panels are typically the least efficient.  

But lately, there have been improvements in thin-film panels, and some are now as efficient as crystalline silicon panels. 

If you’re looking for specific brands with better solar panels, here are some recommendations: 

  • SunPower: They make panels that can be up to 22.8% efficient. 
  • Canadian Solar: Their panels can also reach up to 22.8% efficiency. 
  • REC: They have panels that can go up to 22.3% efficiency. 

As of 2024, there aren’t any commercial solar panels with efficiency ratings higher than 24%. But, scientists are always working on improving solar cell technology 

So this might change soon. Some PV cells have even reached almost 50% efficiency in labs.  

Factors Affecting Your Solar Panel Efficiency

Many things can make your solar panels less efficient. Some, like the weather, you can’t change, but others, like dirt buildup, you can control. 

Hot weather can make your solar panels less productive. You can’t do anything about the weather, but you can get panels that handle heat better.  

Look for panels with a low-temperature coefficient. This number tells you how much productivity the panels lose as the temperature increases.  

Panels with a coefficient below 0.30% per °C lose less than 3% productivity when it gets 10°C (18°F) hotter. 

Dirt buildup and shade are also bad for solar panel efficiency, but you can do something about them. Regularly cleaning your panels can help them work better.  

And if you hire a professional installer, they can ensure your panels are in a good spot where they won’t get shaded.  

For example: 

  • If trees are near your panels, trim branches that hang over them, and watch out for leaves. 
  • If you’re putting something on your roof, like an air conditioner, ensure it won’t cast a shadow on your panels. 
  • New buildings can also cast shadows on your panels. Some states have laws to stop new buildings from blocking your sunlight.

Misunderstandings About Solar Panel Efficiency

Many people think that the efficiency of a solar panel shows how good it is. But efficiency is just one thing about a panel, like how powerful or big it is. There are high-quality panels that are efficient and ones that need to be revised. 

The main thing that decides the efficiency is how they were made: 

  • Monocrystalline silicon panels are usually over 20%-24% efficient. 
  • Polycrystalline silicon panels are typically less than 21% efficient. 
  • Thin-film panels are less efficient, but new materials like perovskite can be as good as silicon. 

So, monocrystalline panels are the best at making electricity compared to other types. They’re better because they make more electricity using less space and cost more. Using more or less efficient panels could also work if you have a lot of room for solar panels. 

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