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Solar Efficiency Rating: Does It Matter?

If you are in the market for solar panels, you have probably noticed that many manufacturers like to tout their solar efficiency rating. For someone new to the technology, it is normal to be a bit confused about what exactly this means and whether or not it is important. Thus, let’s take a look at solar efficiency rating and whether it matters for solar panels in San Antonio.

What is Solar Efficiency Rating?

Solar efficiency rating is a metric that details how well a particular brand and model of solar panel performed in efficiency during testing. A higher rating means that a solar panel was more efficient in producing energy.

Specifically, solar panel efficiency measures the percent of the sun’s energy that the solar panel is able to convert into electricity. Thus, a higher efficiency rating means you are able to generate greater amounts of energy from the same sun exposure. In areas with a lot of sun exposure like San Antonio, this can have a strong impact over the life of solar panels.

What is a Good Solar Efficiency Rating?

The ability of solar panels to harness energy from the sun has improved over time as technology has improved. In the past, solar panels that generated a 15% solar efficiency rating were seen as top of the line. However, that rating today would be seen as fairly low.

Today, solar efficiency ratings above 18% can generally be viewed as very good while ratings above 20% are excellent. In fact, the highest rating currently on the market is nearly 23% while the tenth highest rating is at 20.4%. All of our listed preferred panels have an efficiency rating above 18%.

The improvements in the efficiency of solar panels have come with advances in technology. While a change from 15% to 20% may seem small, this represents an improvement by nearly a third in a fairly short period of time.

Is Solar Efficiency Rating the Primary Thing I Should Consider?

It can be tempting to want to make decisions based on a sole factor; however, the reality is that there are many things you should consider when investigating solar panels. While solar efficiency rating is certainly an important thing to note when evaluating different models, there are many other factors too.

One of the primary things to note is the cost of panels. Different solar panels will have different costs. Typically, better performing panels will be more expensive than lesser performing panels. Thus, you’ll likely want to balance efficiency and cost when deciding.

Fortunately, the overall cost of solar panels has decreased over time compared to their energy benefit. For example, the gross cost per watt in 2017 was $3.17 while the gross cost per watt in 2021 was $2.77.

Will a Panel Always Operate at Its Solar Efficiency Rating?

The solar efficiency rating represents the performance of a solar panel in ideal conditions. Thus, your solar panels will not always operate at that efficiency. In fact, there are a variety of things that affect actual efficiency including the following:

  • Temperature. It might surprise you to learn that solar panels operate most efficiently at lower temperatures. Thus, they will be more efficient in the winter and less in the summer.
  • Your Roof. The direction of your roof can have an impact on efficiency. Ideally, panels can be installed in a way to provide maximum orientation with the sun.
  • Angle. The angle of solar panels is also an important factor that can have slight effects on efficiency. This is something that an installer will pay attention to and discuss with you.
  • Shade. If your solar panels encounter shade from cloud cover, debris, or other sources, this can decrease efficiency as well.
  • Age. The efficiency of solar panels naturally decreases as they age. By the end of their 30 year lifespan, they will typically lose 12-15% of their power generation ability. Thus, a 30 year old panel with a 20% efficiency rating will likely operate at about 17% – 17.6% efficiency.

For more information on these factors, check out our article on Solar Lifespan.

Are Solar Panels Efficient in San Antonio?

San Antonio actually ranks first in Texas and fifth in the United States when it comes to solar energy usage. Additionally, the average cost in 2021 is $3.76 per watt (dc), making solar a great investment in San Antonio. It is estimated that a solar system in San Antonio will pay for itself in 6 – 7 years.

If you have more questions about solar panels, feel free to reach out. We are always happy to chat with you and provide information as you make your decision.

photo taken by Henry Becerra

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Solar Edge Pros is a trusted leader in the solar energy industry. Since 2005, we have provided solar energy solutions to over 5,000 Texas residents making the switch to cleaner, greener, cheaper, solar power. We believe in the positive effects of working hard, treating people with respect, and doing the right thing. Our values transfer to both the customer experience as well as the culture within the Solar Edge Pros Family. 

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