How long do solar panels last? Does their output reduce over time?

Published on 17 Jul, 2018 by Andrew Sendy

10 minutes read

Categories: Solar 101, Solar panels, Solar power, Monocrystalline solar panels, Polycrystalline solar panels, Solar efficiency


Solar panel and man on laptop

When contemplating a solar power system installation on your home, the first question most people usually ask is, how much does a solar installation cost? This is closely followed by, how long do solar panels last? The answers to these questions help you determine whether your monthly energy bill savings is worth the upfront cost and helps us make more accurate long-term solar savings forecasts.

How long have solar panels been around?

The history of solar energy covers 175 years of photovoltaic (PV) solar energy technology and includes extraordinary advancements in the solar energy field. In the 1800's scientists started experimenting with PV energy and how to create electricity using the sun, but they never produced a usable amount of power. This changed in 1954, when Bell Laboratories built the first solar cell that used silicon and a modern era of PV technology began. People began to see solar energy as a viable option for their homes, especially after the oil crisis of 1973. The federal government developed grants and tax incentives in the 1990's to encourage solar system usage.

However, things didn’t really start moving until Germany put in place massive solar incentives in the late 1990’s and early 2000’s. These incentives allowed solar panel manufacturers to reach scale and lead to a precipitous drop in the cost of solar panels. It wasn’t until around 2012 that things really got going in the US when the combination of lower panel prices, utility level rebates, net metering and a federal tax credit made solar affordable to the masses.  

How long do modern solar panels last?

How long you can expect your solar panels to last is an obvious concern when contemplating a large investment. As a general rule of thumb, your solar panels should last at least 25 to 30 years, based on manufacturer testing. The figures used for a solar cost calculator or solar savings calculator are also based on a working life of 25 years. However, life expectancy also depends on the quality of the manufacturing process and installation and the type of solar panel installed.

Amorphous panels, also known as thin film panels have the shortest working life compared to all other types of solar panels. Although they typically still come with a 25-year warranty, they're usually only guaranteed to produce at 80% of their rated output after only 10 years. 

Monocrystalline and polycrystalline solar panels have similar lifespans and also usually include a 25-year warranty, but can outlast their 25-year life expectancy.

Do solar panels go bad?

With the sole exception of tracking mounts on ground-level or pole-mounted panels, solar panel systems don't have any moving parts. This makes breakdowns due to wear and tear highly unlikely, but the chemicals used to make solar panels can deteriorate and break down over time. However, as your solar system ages, it doesn't suddenly go bad. Instead, its power capacity diminishes to a certain degree, which is called degradation.

It is rare for a solar panel to go bad but where it does it is generally due to one of two factors:

  • A breakdown of the microwires inside a cell causing a short circuit (arc) and a hotspot; or
  • The encapsulation that keeps water out of the active part of the panel fails. 

It is hard to know if these problems will occur more commonly as more solar panels from the modern era get older.

How much do solar panels degrade each year?

Degradation rates vary from one brand to another, so these rates are important for a comprehensive solar panel comparison and solar cost calculation. According to a National Renewable Energy Laboratory study, premium manufacturers may offer degradation rates as low as 0.3% per year. Some brands have much higher degradation rates of 0.8% per year, but 0.5% is the average rate. At the end of a 25-year warranty period at 0.5% degradation, panels may still operate at about 88% of their original capacity.

Do solar panels need a lot of maintenance?

Solar panel systems require very little maintenance, but a periodic inspection of your panels is necessary to ensure they haven't developed a buildup of dirt, dust, and other grime. If your panels need cleaning, spray them off with a standard garden hose in the morning before they heat up to prevent cracking. You can also purchase a programmable cleaning system that works similar to sprinklers to routinely do the job, or hire a solar panel cleaning company. Regular cleaning ensures your panels continue to absorb sunlight effectively and efficiently which helps to prevent a dip in your energy production.

What are the typical solar panel repair or replacement requirements?

Solar panels are highly durable and manufactured to withstand high winds, heavy snow, and the impact of airborne debris, including hail. Most solar panels are tested and certified to withstand hail up to one inch in diameter, falling at a rate of about 50 miles per hour. In my 12 years in the solar industry, I have not seen or heard of solar panels being damaged by hail.

Cracked panels, broken glass, and loose connections are the most common repairs required. Cost of materials for these repairs are usually minimal, unless you need to replace an entire panel. Labor costs vary based on the extent of the repair and charged on an hourly rate. What's more common than a solar panel replacement is an inverter replacement. The average warranty for an inverter is 5 to 10 years, but even after replacing an inverter, you can still see a positive return on investment.

Which solar panel lasts longer, Monocrystalline or Polycrystalline?

Monocrystalline and Polycrystalline solar panels

Monocrystalline and polycrystalline solar cells are both made from crystalline silicon. This is a very stable material that makes them more likely to last longer than their 25-year life warranty. Monocrystalline is the oldest and most developed, while polycrystalline is a newer technology, but they’re both very similar in performance and longevity.

What brands of solar panels last longest?

When comparing solar panel brands, check degradation rates and warranties to get a better sense of how long you can expect them to last. Solar panels come with different warranties, including an equipment warranty to certify against manufacturing defects and a performance warranty to guarantee panels will produce a certain amount of electricity. Solar panel brands that offer a 25-year warranty will likely last longer than those that don't. Some premium brands of solar panels now offer a 30-year warranty.

Can you help solar panels last longer?

Solar panels are manufactured to be extremely durable, but keeping your solar panel system well maintained improves panel performance and potentially lowers the yearly degradation rate. For example, heavy snow loads can cause high degradation rates, which shorten the useful lifespan of your solar panels. Keeping snow and other debris brushed off your panels maximizes light exposure and improves your yearly degradation rate, which makes panels last longer.

Which are the best solar panels for me?

Don't just compare solar panel costs to decide which solar panels are best for your home. Compare how efficiently the panels convert sunlight into power and how this changes over time. Do this by comparing top solar panel brands, including ratings and consumer reviews.

 

How much will solar panels cost for your home?

 

 

 

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Author: Andrew Sendy

As chairman of Solar Investments Inc and chairman of the largest solar panel installation company in South Australia, Andy is passionate about solar power. With his unique working background he writes on the residential solar industry in America from a unique perspective.