Do Solar Panels Become Less Efficient Over Time?

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The U.S. Bureau of Labor Statistics found that, in 2020, the average employee stayed with the same employer for 4.1 years.

The product warranty for your average rooftop solar panel is three to five times that length.

Ask yourself, is there a single manufactured thing in your home that doesn’t see a drop in efficiency in that amount of time?

While solar panels are remarkably resilient, they are not immortal. And as such, you can expect solar panels to become less efficient over the years that you have them.

However, it should be noted that this drop in power producing performance is relatively negligible when compared to the performance of other manufactured goods, such as a car or household appliance.

To put it bluntly, solar panels are arguably one of the longest lasting ‘machines’ you will ever purchase.

How Do Solar Panels Last So Long?

To truly understand just how remarkable solar panels are, one has to acknowledge the environment in which solar panels do their work.

Every single day, year after year, your solar panels will face the worst of the elements. Scorching sun, sub-freezing temperatures, rain, hail and snow all come together in a sort of relentless fury.

And yet your solar panels will continue to produce power despite this never-ending assault.

This is largely because of how they are made. The following is a brief list of attributes that contribute to your solar panels longevity.

  • No Moving Parts – With movement, there is always a certain amount of force. This force translates to wear and tear. As solar panels have no moving parts, any force that is encountered is limited to external factors (such as wind, expansion and retraction from heat and cold, etc). This, in turn, limits the amount of wear and tear and thusly extends the amount of time your solar panels will perform.
  • Clever Engineering – If you were to dissect a solar cell, you would likely find bits of semiconducting materials laced with small fragile wiring. This delicate sandwich of sciency stuff however, is covered with a protective layer – the recipe of such, being constantly refined and improved.

It is, in fact, this protective material that contributes to the long lasting efficiency of your solar panels.

  • Out Of The Way – The placement of your solar panels is crucial to their ability to produce power. By some stroke of luck, this generally requires them to be up and away from the general flow of our lives.

Situated in this environment limits the amount of ‘accidental’ contact that could damage and thereby shorten the life of your solar panels.

Solar Panels: Maintenance Vs No-Maintenance

There are two schools of thought regarding the maintaining of your solar panels, with opinions firmly entrenched in both.

For some, a regular cleaning routine, by a solar panel professional, is strictly followed. This is done with the intent of having the highest level of power output from your investment while, hopefully, extending the life of your solar panels.

Others, however, prefer not to ‘fiddle with it’ opting instead to let the rain gently wash away any dust or grim that would make your panels less efficient.

Whatever your personal stance may be, it is absolutely critical to remember that the protective coating on your solar panels must be treated with care. Any scratches or abrasions, no matter how minute, will cause a lasting loss in efficiency from your panels.

80 Percent Efficiency At 25 Years

Just because solar panels can still perform after a couple of decades, how does one gauge if they are performing well?

The general standard to which most solar panels are manufactured to is have an efficiency level of at least 80% after twenty five years.

In other words, if your solar panels are capable of producing 10,000 watts the day you have them installed, then after 25 years, they should still be capable of producing a minimum of 8,000 watts.

That is a 20 percent drop in 25 years – or less than a 1 percent decrease per year from the original efficiency level.

WARNING: Manufacturer Warranty

One of the things that I found notable when first learning about solar panels, is that warranties can be very confusing.

Case in point, my particular manufacturer guaranteed a performance of 80 percent efficiency at 25 years (just like most of their competition). However, the panels themselves were not guaranteed for 25 years, but rather for a substantially less amount.

This caused me no small amount of confusion. How can performance be guaranteed when the item that is doing the actual performing is not?

Welcome to the world of warranties!

Depending on the individual manufacturer, what you will most likely find is, in fact, two separate warranties; one that applies to the construction of the panel, the other to how the panel performs.

In other words, if your panel came apart due to poor manufacturing, then you would be entitled to some sort of compensation, provided this happened within the predetermined time frame – say 10 to 15 years. Think of this as a product warranty.

Assuming that your panels do to stay together for 25 years, then you could expect a certain level of power production. Think of this a performance warranty.

Now that we understand the subtle nuisances of solar panel warranties, here is where things get really challenging.

It turns out that the panels that I purchased in 2015 are no longer being manufactured. They have been replaced by a substantially more capable solar panel. Consequently, an exact replacement is not going to be available should one of my current solar panels fails due to poor manufacturing.

So where does that leave me?

I have no idea!

Because of this, it is my opinion that solar panel warranties, in general, should be taken with a grain of salt and that the reputation of a manufacturer should be very seriously considered when choosing a panel for your needs.

Solar Panels: Associated Sub-Components

While the performance warranty on your solar panels could be at 25 years, it is very doubtful that the warranties on the necessary sub-components will be that long. Some of these sub-components are:

  • Electronics – Necessary electronics can include things like inverters or charge controllers. (Keep in mind that none of these things like heat. This is relative as most people place these crucial electronic systems in a hot garage.)
  • Racking – The mechanical components necessary to mount panels. (Sometimes mounting screws can come loose over time, causing damage to your panels or to your roof.)

Also, if you are utilizing whole house batteries, it is very likely that you will have to replace them long before you see the need to replace your panels. Energy storage technology is a very rapidly developing field. However, at the moment, whole house batteries have not proven to have the same resiliency as solar panels.


While it is true that solar panels do become less efficient over time, between their rapid development and continuing drop in cost, one should still find that a return on investment is met long before the warrantied 25 years has past.

In fact in our case, we are wanting to upgrade our system to include even more panels in anticipation of higher demand for electricity – via an electric car (or cars), electric riding lawnmower, electric go-karts, motorbikes, ect.

Being able to provide your own power is whole lot more convenient than taking trips to the gas station or finding a place to store the smelly fuel. Not to mention, our power comes from a renewable, non-polluting source.

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