Efficiency of Solar Panels

5 Factors that Affect the Efficiency of Solar Panels

As California’s leading solar installation company, we constantly get questions about our solar panels. And for good reason — solar energy can be a significant investment, and we commend every homeowner who wants to know as much information as possible about the solar panels being installed on their home. Naturally, some of the most common questions we get pertain to the longevity and efficiency of solar panels.

How long do solar panels last? Do they get worse over time? Will I ever have to replace them? How much would it cost if I did? What can I do to ensure maximum performance? These are all great questions, and we hope to answer them in this blog post. Let’s take a look at the various factors that will affect the long-term efficiency of solar panels.



CalendarThe first factor that needs to be considered is the age of the solar panels. And this, again, is one of the most common questions. The prospect of saving money on your energy bills sounds great on paper, but it would be a much less enticing prospect if the solar energy system pooped out after five years or so.

Luckily, that’s not the case. Solar panels will work for a good 25 years or so before they start to show signs of slowing down. And even after that, they won’t just stop producing electricity — they might just operate at a lower efficiency. On average, solar panels have an annual degradation rate of .05% – .07%, depending on the panel manufacturer. This is partly due to natural wear-and-tear, but it can also be caused by other factors, many of which will be addressed in this post.

What’s important is the rated production output of solar panels, which is basically another term for overall efficiency. Most solar panels have a warranty, in which there is a guaranteed rated production output from the manufacturer. The warranty usually assures homeowners that the solar panels will work at (or within a very close margin of) that output for a predefined amount of time, usually 25 years. After that, there’s no guarantee that the panels will be as efficient, but you also won’t have to worry about them up-and-dying on you.

Installation Issues

Unfortunately, age and natural usage isn’t the only thing that can influence the efficiency of solar panels. Sometimes there are problems that are caused from the very start, caused by a less-than-stellar installation job.

It’s important to remember that solar panel installation is not a simple or easy job. It’s not just a matter of installing panels onto the roof — because the solar system is a source of energy for the entire home, it has to connect with the electrical grid, and a careless installer might not implement these connections as well as they require. The condition of the roof is also a major factor. We always analyze our clients’ roofs in great detail, because their condition will affect the way we approach the installation process. The age of a home, and the state of their electrical panels, breakers, and wiring — these are all things that can affect solar panel installation.

At Energy Service Partners, we’ve been in the solar industry for decades, and we’re cognizant of all the little things that can go wrong in the installation. As California’s leading solar installation company, we prioritize the quality of our installation service above all else, so that you can have the peace-of-mind knowing that your system will last.


Sun behind clouds affecting solar panel efficiency Solar panels are designed to stand on top of your home all day, every single day, for decades. For this reason, they’re engineered to hold up well against the elements, but that’s not to say they’re completely immune. Weather can indeed have an effect on your solar panels, and in extreme conditions, can even degrade them.

The good news is that this doesn’t happen very easily. As we mentioned above, solar panels are designed to be exposed to the elements for their entire lifespan, so there’s a lot of intentionality in their design to ensure that they hold up well. But no piece of technology is completely resilient to damage. Weather can directly damage a solar panel. Abnormally large and heavy hail can damage the glass, and excessive snowfall can reduce the structural integrity. There are also secondary damages that can be caused by weather, such as powerful winds causing a tree to fall onto the solar panels.

There’s a silver lining to all this, though — the weather in California just isn’t that bad. The overwhelming majority of our days are pleasant and sunny. Snowfall is extremely rare in most areas of the state, and hail is seldom ever strong enough to make an impact. Our solar panel systems are extensively tested against inclement weather, so this is most likely a factor that you won’t have to stress out about.

Mounting Position

This is somewhat related to the points we mentioned above regarding installation issues. In the paragraphs above, we mentioned degradation that can result from poor installation, but there’s another aspect that can lead to efficiency issues later on, and that’s the orientation of the panels on your roof.

Even if your solar panels are perfectly installed with zero issues in the connections or structural integrity, they might not work at optimal efficiency if they’re not oriented well. Because solar panels absorb sunlight, they should be positioned in such a way that they get as much exposure as possible at all times of the day.

There is a science to orienting solar panels the right way, and it’s different from house to house. The solar installer has to consider where the sun will be during every hour of the day. A panel oriented at one angle might receive 100% sunlight at, say, 9 AM, but it might get way less at 6 PM. The goal with solar installation is to position the panels to where they’re receiving the optimal amount of sunlight during all hours of the day. This is a group effort between all the panels, and we spend a lot of time calculating their exact positions and angles. This is just one of many reasons why Energy Service Partners is one of the most renowned solar installers in the industry — we look at every single aspect of the installation with a painstaking attention to detail.


This may be surprising, but did you know that hot temperatures can actually impede the efficiency of solar panels? This is due to the common misconception that they’re powered by the heat of the sun. In reality, heat has little to do with it — it’s all about the UV rays. This is why solar equipment works so well in space. Despite the fact that space is a freezing vacuum, there’s an abundant amount of UV light that can power satellites.

With that being said, pretty much any type of technology is susceptible to overheating. While California is temperate enough to not be scalding hot, it is possible for exceedingly hot temperatures to affect the performance of solar panels. There are ways to mitigate this problem, such as being installed in a way that allows for good airflow. This is another thing that we pay close attention to when we install solar power systems for California homeowners.

California’s Leading Solar Installation Company

At Energy Service Partners, we believe in the power of solar energy — not only as a great way to save money on bills in the long run, but also as a way to move mankind forward into a future of renewable energy. Because of that, we want every single California home- and business owner to have the best solar experience possible, and that’s why we’re the leading solar installation company in the state. We acknowledge that solar panels can degrade and experience reduced efficiency if the installation is anything less than perfect. Whether you’re a homeowner who needs a quality solar energy system, or a solar sales company who is looking for a great installation partner, Energy Service Partners is the team to call. Contact us today to get started!

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