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Underperforming solar panels: common causes and solutions

The number of solar panels installed worldwide increases substantially each year with advancements in technology, increasing environmental awareness, and decreasing costs. Solar is more accessible than ever, making it a more and more attractive energy option for businesses, residents, and utilities. However, as more solar panels are produced, the chances of them malfunctioning or underperforming increases as well. In this article, we’ll explain why your solar panels may be underperforming and the actions you can take to mitigate and monitor your risk.

Key takeaways

  1. Like any product, solar panels can underperform after they’re installed

  2. You can identify underperforming panels with a monitoring system or energy management system

  3. Explore your solar options are on the EnergySage Marketplace to connect with reputable solar installers

What can cause solar panels to underperform?

Since 2019, multiple solar industry experts have teamed up to produce the Solar Risk Assessment: a report designed to provide insights on solar generation risk to solar financiers. The latest version of the report, the 2021 Solar Risk Assessment, found that median annual degradation was about 1.09 percent for residential solar systems – about a quarter more than what most panel warranties estimate (0.8 percent). They also found that many panels are chronically underperforming. So, what’s causing this degradation and underperformance? 


If your solar panels are underperforming, it’s possible that the problem originated when the panels were being manufactured. Solar panels may be chipped or cracked in production, often signifying that the manufacturer did not use premium materials. Additionally, the manufacturer may be using a manual soldering process rather than an automated one, which can translate to higher break rates. Scratches or breakages of any kind can lead to output degradation, and even more technically, the way solar panels are wired both internally and externally (to the inverter) can lead to decreased output as well, a problem that typically arises in the manufacturing or installation process.

Due diligence is a crucial step in the manufacturing process to determine risk for all parties involved in a solar project. Due diligence provides technical information on output estimates, environmental permitting, and just about everything else that needs to be factored into financing a solar project. PV Evolution Labs (PVEL) is a company that conducts solar panel lab performance testing to support solar panel buyers in their process of choosing the right solar panels and seeking out the correct performance metrics. PVEL measures and monitors product quality metrics to keep pace with the evolving product landscape of the solar industry. As the solar industry continues to evolve and grow, it’s important for companies like these to conduct research on solar panel reliability to reduce the frequency that underperforming solar panels reach the market.


When you’re installing solar panels, it’s important that you choose a qualified installer that can accurately assess any potential shading on your roof, as it can and will affect energy output. There are many things that can contribute to shading such as trees, clouds, or even your own solar system, so quantifying and mitigating these risks is crucial to having an efficient solar system.

Check out our article on solar panel shading to learn more about the specifics.


Solar panel defects, whether they happen in production, manufacturing, shipment, or installation, can become grave problems for your energy output if they go undetected or unfixed. Some solar panel defects to watch out for are delamination, induced degradation, and snail trails. While some defects are treatable, such as electrical issues or some unwanted animal activity around your panels, others require an inverter replacement, or a whole module replacement if your system is chemically degrading.

Check out our article on the most common solar panel defects for a deeper dive into what can actually go wrong.

Extreme weather

Once your panels are on your roof, they face the risk of extreme weather, which can lead to severe damage and underperformance. If you live in an area prone to wildfires, you could see performance issues due to the haze caused by smoke. If substantial soot is produced, you may also need to have your panels cleaned to remove any excess soot that might be covering your panels.

It’s also possible that you might see some damage due to other extreme weather events, such as hurricanes and hail storms. However, solar panels are designed and tested to withstand such events, which is why due diligence is such a critical part of the solar panel manufacturing process.

How to tell if your solar panels are underperforming

First and foremost, you should be aware of your solar panels’ expected output. The wattage, or power output of your solar panels will determine how much energy your panels will produce out-of-the-box. However, each year, your panels will degrade slightly, causing the output to decline. By visiting the EnergySage’s Buyers Guide, you can compare the warranty specifications of different solar panels to assess the predicted degradation over your panels’ warranty term. If your expected output doesn’t match real-time output, something might be wrong, so it’s important for you to reach out to your installer.

Another way to assess if your solar panels are underperforming is to monitor your energy bill. If your energy bill is spiking–and you don’t feel like you’re consuming more energy than usual or there hasn’t been particularly inclement weather–it’s worth checking in with your installer, as there could be something wrong with your system. Another great way to track your energy usage is through an energy monitor or an energy management system. With either setup, you’ll be able to see how much energy you’re consuming and how much power your panels are generating, to assess if anything might be wrong. With an energy management system, you’ll also have the added benefit of remotely controlling your devices at the circuit level.

Explore your solar options on the EnergySage Marketplace

Finding a reputable installer with high quality solar panels is the first step in reducing your risk of underperforming solar panels. On the EnergySage Marketplace, you can compare multiple quotes from local, pre-screened installers to find the solar system that meets your needs at the right price. If you’re not in a position to install solar on your property, you can also check out our Community Solar Marketplace to see if there are any available projects near you!

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