Solar
How Efficient Are Solar Panels After 10 Years?
Virginia homeowners want to know their solar system will still perform a decade from now. Here is what the data actually shows about long-term panel efficiency.
Earth Right | Solar | 5 min read
0.5%
Median annual degradation rate for crystalline silicon panels (NREL)
90–95%
Of original output retained after 10 years of operation
25–30 yrs
Expected operational lifespan of modern solar panels
The Problem
What Homeowners Do Not Know About Long-Term Solar Performance
One of the biggest questions homeowners have about solar is what happens after the system has been on the roof for a while. A solar system is a long-term investment, so it makes sense to look beyond the first year or two. How much electricity will the panels still produce after 10 years? What about 20 or 25 years?
Modern solar panels are designed to keep producing electricity for decades. They gradually lose some of their original output as they age, but the change happens slowly. After 10 years, a well-maintained system can still be producing around 90% to 95% of what it produced when it was new.
That makes the long-term performance of solar much more predictable than many homeowners realize.
Panel Performance
How Long Do Solar Panels Last?
Most modern solar panels have a useful life of 25 to 30 years or more. That does not mean a panel reaches year 25 and stops working. Solar panels gradually produce a little less electricity over time. The industry refers to this as degradation, which is the normal aging process of the solar cells.
Research from the National Renewable Energy Laboratory has found a median degradation rate of about 0.5% per year for crystalline silicon panels. The change from one year to the next is small.
After about 10 years, panels typically retain 90% to 95% of their original production capacity. After 20 years, they can still retain roughly 84% to 90%. At 25 years, many panels remain in the range of 80% to 88% of their original capacity. The panels continue generating electricity long after the initial installation, even though their annual production slowly decreases.
Newer panel technology can perform even better. Many modern N-type panels, including TOPCon and HJT models, have degradation rates around 0.25% to 0.40% per year.
~3,420
Virginia Climate
Virginia Factors That Affect Your System Over Time
Solar panels spend their entire working life outside, so the local climate matters. Virginia gets plenty of sunlight for solar, but the state also has hot and humid summers, cold weather, temperature swings, and heavy seasonal pollen. Solar equipment is designed to handle these conditions, but keeping an eye on the system helps it continue performing well.
Pollen is one of the more noticeable seasonal issues for Virginia homeowners. During the spring, pollen from trees such as oak and pine can build up on the surface of solar panels. A light coating may have little effect, but heavier buildup can reduce the amount of sunlight reaching the solar cells. Rain will remove some of that buildup, but it does not always remove everything. Cleaning the panels can help bring production back up when debris has accumulated.
Trees are another factor worth watching as a system gets older. A tree that was small when the panels were installed may eventually grow tall enough to shade part of the array. That can have a much bigger effect on production than the gradual aging of the panels themselves.
Worth Knowing: New shading from tree growth is one of the more common reasons an older system underperforms. If production has dropped noticeably, checking for new shade is a good first step before assuming the panels are at fault.
System Components
Solar Panels Are Usually Not the First Part of the System to Age
There is another piece of the system homeowners should know about. The inverter converts the electricity produced by the panels into electricity your home can use. String inverters commonly have an expected lifespan of around 10 to 15 years.
That means an inverter may need attention or replacement while the solar panels still have many productive years ahead of them. If a 12-year-old solar system suddenly stops producing electricity, that does not mean the panels have reached the end of their life. The inverter or another electrical component may be the issue.
A system that is 10 or 15 years old may still have plenty of value, even if one component needs to be repaired or replaced.
10–15 yrs
Warranties
What Your Solar Warranty Covers
Solar manufacturers typically provide two types of warranties. A product warranty covers problems with the panel itself, such as manufacturing defects. Depending on the manufacturer, these warranties commonly last 10 to 25 years.
A performance warranty addresses how much electricity the panel is expected to produce as it ages. Many manufacturers guarantee that their panels will still produce at least 80% to 85% of their original rated output after 25 years. Some higher-end panels carry warranties with higher guarantees.
When comparing solar panels, it is worth looking at the details of the performance warranty rather than focusing only on the number of years covered. A linear warranty establishes an expected rate of degradation over the life of the panel, giving homeowners a clearer picture of how the manufacturer expects performance to hold up over time.
Where to Start
A Practical Sequence for Virginia Homeowners With an Aging Solar System
Review Your Monitoring Data
Most modern systems have an app or online portal showing how much electricity the panels are producing. Comparing production across several years can identify whether the system is performing normally. A gradual decline is expected. A sudden drop is not.
Inspect for Debris and Shading
Check the panels for heavy dirt, pollen, leaves, or other buildup. Also look at nearby trees. A tree that has grown significantly since installation may now be shading part of the array during peak production hours.
Clean the Panels If Needed
If pollen or debris has accumulated, cleaning the panels can restore production. This is a straightforward maintenance step that is easy to overlook, particularly after Virginia’s heavy spring pollen season.
Schedule a Professional Evaluation
If production is still lower than expected after cleaning and a visual inspection, a professional evaluation can identify what is actually happening. Common issues include aging inverters, damaged connectors, and panel defects that are not visible without diagnostic equipment. Getting a diagnosis before replacing equipment can save significant cost.
Common Questions
Frequently Asked Questions
Do Solar Panels Need to Be Replaced After 10 Years?
No. Modern solar panels are built to operate for 25 to 30 years or longer. Most retain 90% to 95% of their original production capacity at the 10-year mark. Replacement at that point is not typical or necessary under normal conditions.
Why Did My Solar Production Suddenly Drop?
Normal degradation happens gradually, not all at once. A sudden drop usually points to a specific issue: inverter failure, a tripped breaker, new shading from tree growth, or debris on the panels. A monitoring check and basic inspection will often identify the cause quickly.
How Much Efficiency Do Solar Panels Lose After 10 Years?
Based on the industry standard degradation rate of around 0.5% per year, most modern panels lose approximately 5% to 10% of their original efficiency during the first decade. Premium N-type panels can lose as little as 2.5% to 4% over the same period.
Does Pollen Really Affect Solar Production in Virginia?
Yes. Heavy pollen accumulation during Virginia’s spring season can reduce output noticeably. Rain clears some of it, but not always enough to fully restore production. In high-pollen areas, cleaning the panels once a year can make a measurable difference.
What Is the Difference Between a Product Warranty and a Performance Warranty?
Find Out How Your Solar System Is Actually Performing
Earth Right provides solar assessments, system diagnostics, and energy solutions across Virginia. A conversation with our team starts with your home.
Call us at 434.661.5656 or email info@erepower.com