Solar Panel Lifespan and Degradation Curve

Solar Panel Lifespan and degradation curve

Installing solar panels in your home can provide several benefits — lower electricity bills, a reliable energy source, and an increased home value. There is no doubt that getting solar panels installed in your home is a worthwhile investment in the long run. But, as with any significant investment, smart homeowners usually wonder: How long are these solar panels going to last?

The short answer is: quite long a time!

Solar panels, like all technical equipment, wear down over time and may require replacing. The good news, however, is that they degrade very slowly and can produce electricity even decades later! This doesn’t alter the fact that solar panels do lose efficiency as time goes on. There are two main reasons for this. The first is that continuous exposure to the sun’s ultraviolet rays cause degradation in the solar cells, which in turn decreases the power output of the system. The second reason includes various factors such as weather that may cause damage to the solar panels. These factors are typically covered under the solar panel warranty.

In this blog, the topics we’ll discuss in detail are solar panel degradation, different types of solar warranties, and tips to make your solar panels last longer.

Solar Inspection

What Is Solar Panel Degradation and What Causes It?

Due to the constant exposure to sunlight, the solar panels degrade over time. You might wonder, how does this happen? Factors like heat, humidity, physical damage from falling debris, and thermal cycling (alternating hot and cold temperatures at high rates of change) can lead to the development of microscopic cracks in the silicon of the solar cells. These cracks eventually weaken the electrical connections in the solar panels and reduce the energy output of the photovoltaic (PV) system.

In the past, solar panels would typically see a decrease of 1% or more in power output each year. This is known as the solar panel degradation rate. According to a 2012 study by The National Renewable Energy Laboratory (NREL), modern solar panels show no more than 0.8% loss of power per year. This means that by the end of their useful life expectancy (typically 25 years), the average solar panels will still be operating at 82.5% of their original capacity.

However, as solar technology has improved considerably, it’s now possible to find solar panels that decline by even less than 0.8%. At Smart Solar Energy, our solar panels come with a guarantee that they will degrade by no more than 0.6% per year, which means they’ll still be producing 85% of their original capacity after 25 years.

This is an incredible feat, considering the harsh conditions that solar panels have to withstand all year round.


What Is the Degradation Rate of My Solar Panels?

Different manufacturers offer different guarantees for their solar panels. You can check the warranty coverage on the manufacturer’s website. You will typically find two types of solar panel warranties available:

  • Solar Panel Product Warranty: This is the standard manufacturer’s warranty available which covers manufacturing defects, premature failures, and protection against faulty equipment. The shortest warranty period available for home solar panels is 10 years, but with Smart Solar Energy Co., you get an industry-leading 25-year warranty.
  • Solar Panel Power Warranty: As we mentioned above, solar panels degrade over time. The power warranty guarantees the amount of power generated at different points during the lifespan of the solar panels (5, 10, 25 years). If the power output is lower than promised, the manufacturer will cover the replacement costs or reimburse you for it. 25 years is considered the standard length for a power warranty.

Pro Tip: Always read the fine print on the warranty to understand what the specifics of the warranty are. This will ensure that the warranty terms are suitable for your particular needs. Teaming up with a qualified and reputable solar installer would help you get the best warranty plans that will cover problems such as physical damage due to weather, performance issues, repairs, theft, etc.

Solar Panel Power Warranties: Important Figures

There are two important things you should be focusing on when going through the details of a solar power warranty:

  • How long the warranty will last – Most solar panel manufacturers on the market offer at least 25 years of guaranteed power generation. If you’re being offered a shorter length for your warranty, you should consider it a red flag and consult some other installers.
  • What is the power output warranty – This number should tell you the expected power output of the system once the warranty period has ended. It will be a percentage of the original power output of the panel when it was first bought.

For example, a 350-watt solar panel with an 80% power output guarantee for the duration of 25 years should be producing 280 watts after 25 years.

Note: Manufacturers test solar panels in a laboratory before they’re brought into the market. Based on these tests, they assign the panels a power rating (in watts), which indicates the efficiency of a panel. This is called a Standard Test Conditions (STC) rating. Since the real conditions that solar panels are put into differ from laboratory conditions, they produce less output than the STC rating. So, a 350-watt panel installed on your rooftop will generate less output than the stated efficiency rating. You should measure your solar power output against the initial production when the panel was new, and not the STC rating.

Solar Technology

Most manufacturers in the industry will guarantee that their solar panels will not lose more than 20% of their efficiency at the end of the 25-year warranty period. Of course, better panels will have a higher power output guarantee, which means more savings over the system’s lifespan.

Power Warranties and Solar Panel Degradation

Besides the warranty duration and it’s power output guarantee, there is one other important aspect of solar panel power warranty: the rate of power degradation, which is defined as the decline in power output over a period of time. You’ll find the expected solar power degradation rate for the first year in the warranty details.

Most solar panel warranties estimate the rate of power degradation to lie between 2% to 3% in the first year, and then 0.7% a year after that. However, depending on the quality of solar panels, it could be as low as 0.25%.

The reason there is a higher degradation rate in the first year can be explained by a phenomenon called light-induced degradation (LID). During the first few hours of exposure to sunlight, the solar cells experience a loss of performance due to the formation of boron-oxygen complexes in the silicon wafers that make up the solar cell. After a few days, the degradation rate lowers and remains steady for the rest of the panel’s useful life.

In case your solar panel’s performance falls short of the guarantee, the manufacturer will either replace or repair it. In some cases, the cost of shipping and labor may also be covered.

Performance Warranties Offered by Leading Manufacturers

The table below lists the various 25-year power warranties offered by some of the top solar panel manufacturers in the market.





Auxin Solar


Boviet Solar


Canadian Solar


CertainTeed Solar


First Solar


Global Solar






Q Cells


REC Solar


Recom Solar




Trina Solar




As you can infer, most manufacturers offer an 80% power warranty, while there are some that guarantee above 90% output at the end of the 25 years. We at Smart Solar Energy Co. believe in delivering a high-quality service and offer an 85% power guarantee, higher than most other installers in the industry. If your solar panel system’s production falls below 85%, we will compensate you with cash!

How Significant Is the Difference Between 80% and 92% Degradation?

All solar panels degrade over time, although their rates differ. And this difference between degradation rates can prove out to be significant at the end of your solar panel’s useful life. While a good quality panel may degrade by only 9%, a cheaper panel could lose 20% or more of its efficiency.

Let’s understand this with the help of an example. Suppose there are two 350-watt panels, Panel A and B, with power guarantees of 92% and 80% respectively after 25 years.

Panel A will produce 322 watts of power output after 25 years whereas Panel B will produce only 280 watts of output.

This difference is significant, especially when you consider that there are several panels installed in a household to power it fully, not just one.

However, the prices of panels also differ. A panel that guarantees 92% power output will cost much more than one that assures 80% output. You should discuss the pros and cons of both with your solar installer.

What Causes Unexpected Solar Panel Failures?

Apart from factors that are expected to cause wear and tear in solar panels such as LID, there are some other, less frequently occurring factors that may reduce the efficiency of solar panels. These are:

  • Potential-induced degradation (PID)

PID occurs when the photovoltaic (PV) modules operate at a negative voltage with respect to the ground. This causes the leakage of current from solar cells to the frame and can reduce the panel’s efficiency by 30%. Voltage, heat, and humidity can affect the extent of PID in solar cells.

  • Hot spots

Hot spots are small areas of high temperature that cause a localized decrease in efficiency. Cell mismatch, damaged solar cells, and partial shading can all cause hot spots.

Some other causes of unexpected panel failure are delamination, wiring issues, and cracked glass.

Solar Panel Standards and Maintenance Tips

Before solar panels become available in the market, they undergo rigorous testing to ensure their quality. IEC 61215 is one of the most important standards that involves various tests that solar panels must undergo before they are certified. The parameters it covers are: sunlight (including UV rays), climate, and mechanical load (hail, snow, wind pressure).

There are 19 tests in total that a solar panel goes through to ensure maximum efficiency and quality.

Although these tests make sure that solar panels are durable and can withstand harsh conditions, there are some steps you can take to increase the solar panel lifespan. Firstly, make sure that you are pairing up with a reputable and professional solar installer with stellar customer service. Next, conduct regular maintenance checks on your panels if your installer doesn’t provide monitoring. At Smart Solar Energy Co., we provide 24/7 real-time monitoring of your solar panels, because catching issues early on will allow you to fix them before any extensive damage occurs. Lastly, if you notice a significant change in power output, consider calling a professional to assess the situation.

Maintaining your solar panels is not a hard task, and with a good warranty, you can sit back and relax for at least 25 years.

Looking To Put Solar On Your Home?

Whether you are looking for a residential solar provider or commercial solar energy systems, our team at Smart Solar Energy can help give you all the information you need and the cost of solar installation. We provide free solar quotes for any project you may have. Simply use the link below to get a free solar audit today:

Solar Energy

Does Solar Make Sense in Oregon?

When it comes to solar, last year’s facts are this year’s fiction. The solar industry changes at a rapid pace, leaving prospective solar buyers reading

Read More »