Solar panels typically last about 20-30 years, including at least one swap of their inverter, which needs replacement every 10-15 years.
There are a few different factors that can contribute to your solar panel’s wear and tear. Below you’ll find some of the most important things to know about a solar panel’s lifespan and how to answer the question “How long do solar panels last?” fully.
How Long Do Solar Panels Last on Average?
Most solar panels available on today’s market typically last between 20-30 years (1). The inverter mainly drives solar panels (also known as “photovoltaic, or PV, panels”). This is a component of the PV system that converts the sun’s rays into an alternating current, preparing it for use by the U.S. electric grid.
The inverter consists of several pieces, including:
- Active switches
- Passive filters
- Thermal management mechanisms
- Weather-resistant packaging
All these elements are degradable. Once the inverter and its parts wear down past a certain point, it requires more repair and replacement than it’s worth. At this point, it’s more environmentally and economically responsible for replacing the panel altogether (1).
Solar panels on the market today can last for 20-30 years and now it’s time for their power electronics counterparts to evolve to help PV systems last even longer.
However, not all solar panels are of the same quality, so this range may change depending on your panel’s make and model and whether it’s been damaged or not. Knowing the average degradation rate for most solar panels can also help form your expectations for when you might need to look into a replacement for your energy system.
How Fast Do Solar Panels Degrade?
According to a National Renewable Energy Laboratory (NREL) study, the average solar panel’s performance weakens by about 0.5% annually (2). Their work revealed that the famous “1% rule” of annual solar panel wear was significantly low and underestimated the technology’s longevity.
Most people assume that solar panels degrade at 1% per year. This is an overestimation.
While this may have been the case for panels made several years in the past, the engineering has improved over the years and extended most panels’ longevity. Plus, the rate at which they break down depends on the material.
For example, most commercial and residential solar panels use monocrystalline silicon, similar to a typical 100-watt solar panel you’ll find for home use. Before 2000, these types would degrade at about 0.5%. As manufacturing techniques improved post-2000, this rate fell to 0.4% (2)
A panel manufactured today should produce 92% of its original power after 20 years, quite a bit higher than the 80% estimated by the 1% rule.
That said, other products like solar attic fans can keep up with this timeline, especially when installed by a professional. This also stands true for other solar household necessities like solar pool heating systems (lasting about 20-25 years normally). In fact, here are a few more examples of the dramatically improved lifespans for various solar home goods:
- Solar-powered waste compacting bin: 3-4 weeks, since it runs on a battery that is charged by the solar panel
- Solar furnace or water heating system: 20 years (significantly longer than gas or electric system)
- Solar pump: 2-4 years
Remember that another crucial factor in determining how long do solar panels really last is the environmental conditions in which it operates.
Those exposed to more extreme conditions, such as exceedingly high UV exposure levels or heavy snowfall, will fall in quality much more quickly than a panel installed in a moderate climate. For instance, panels in the most moderate regions of the U.S. have been known to degrade at only 0.2% per year.
How Often Do Solar Panels Need to be Replaced?
The next step in answering our query, “How long do solar panels last?” starts with looking at their power generation performance.
To ensure optimal performance, you should replace solar panels as soon as their efficiency falls below an acceptable rate. For ballpark numbers to look for, you can think about it like this:
Solar panels should be replaced once they drop below 80% efficiency. Most manufacturers estimate this to be about 25 years.
Still, how do you know when your solar panel needs replacement or has fallen below the target efficiency level? Here are some things to look out for:
- Voltage and output: Any readings that are 20%+ lower than the promised output is a sign that the panel is wearing down.
- Physical condition: If your panel was damaged by blunt trauma or a severe weather event, you might want to consider extensive repairs or getting it replaced.
- Mechanical components: As you learned, solar panels contain several different parts to gather and convert the sun’s energy. If pieces like the inverter, wiring, or battery start to wear, the entire system is compromised and won’t work efficiently.
Remember to look for solar panels that come with at least a 20-25 year warranty. Also, make sure they’re built with durable materials to get the most out of your system with minimal maintenance. For example, Sun Power offers a 25 year warranty on their panels, and they’re flexible to the elements:
Ultimately, the advances in solar technology continue to increase their lifespan’s at a speed no one could have imagined just a few years ago.
How Do I Know if My Solar Panels are Going Bad?
The clearest sign that your solar panels are going bad is if their output falls significantly far below the manufacturer’s listed standards. Specifically, if it’s more than 20% below what the maker guaranteed, it’s time to get a new panel.
What Happens to Solar Panels After 25 Years?
The most common issue with solar panels after 25 years is that the inverter and its functioning pieces begin to break down. This prevents the necessary conversion of solar energy to usable energy for the grid, ultimately costing you power.
How Long Does a Solar Inverter Last?
A solar inverter should last around 10-15 years and be replaced at least once during your panel’s lifetime. When the solar inverter and its components degrade over time, the replacement or repair becomes more expensive getting a new inverter that performs with more efficiency is the better investment.
- Extending solar energy system lifetime with power electronics. Energy.gov. https://www.energy.gov/eere/solar/articles/extending-solar-energy-system-lifetime-power-electronics
- What is the lifespan of a solar panel? by TomLombardo. Engineering.com. https://www.engineering.com/story/what-is-the-lifespan-of-a-solar-panel