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How long do solar PV panels last?

Posted by Alex Barrett on 26 July 2016 at 5:05 pm

It can take years for a solar photovoltaic (Solar PV) array to “pay back” its installation cost, so you want the panels to last as long as possible. So just how long do solar panels last? And how does their efficiency decrease across their lifetime?

The aging of solar cells can be quite difficult to assess, since solar panels are a relatively new technology. The photovoltaic effect was only discovered in the mid nineteenth century, and it wasn’t until the 1950’s that solar cell production began [1]. Solar panels have only become widespread since the end of the 20th century, so very few installations are more than one or two decades old.

This means that very few panels have reached the end of their life, and there has not been time for manufacturers to conduct multi decade long studies. This means that there is very little information about how the efficiency of a solar cell changes over time. Manufactures have to rely on laboratory tests, conducted over an accelerated timescale. They can bombard solar cells with radiation, and cycle temperatures to simulate years of exposure to the elements, but this sort of test doesn’t perfectly simulate the problems that occur over longer periods of time [2].

Most solar panel manufacturers have warranties which guarantee their products for the first 20 years of their operation. They claim that efficiency shouldn’t drop below 80% during this time period. The Feed-in Tariff scheme assumes that panels will remain economically viable over a lifetime of 25 years. It is generally assumed that a modern solar cell will last longer than this, potentially for as long as 50 years before their output decreases to a level where they are no longer viable [3].

This is supported by the current efficiency of some of the earliest solar PV installations. It has been reported that one of the first prototype photovoltaic devices still performs well sixty years later [4], and many old panels have not seen a large drop off in efficiency [5, 6]. The UK’s first grid connected system is still 95% efficient after 20 years [7] and many 30 year old systems still produce more than 80% when maintained correctly.

The efficiency of different types of solar panel is expected to decrease at different rates, but this is usually less than a percent per year [8]. Many solar PV systems experience a sharp initial drop off in efficiency during their first year of operation. You shouldn’t be too worried if the output decreases by up to 5% over the first year. In most cases this levels off fairly rapidly and efficiency will decrease much more slowly over the rest of the life of the panel.

Some devices will perform better than others. Many will far outlive their predicted lifespans, while others might have faults which limit their effectiveness in the long run. Fortunately there isn’t much that can go wrong with solar panels. The electrical contacts could corrode, and water could damage the lamination, but the solar cell itself is very robust.

While the panels themselves won’t need to be replaced this is not true of peripherals such as the invertor and batteries. The invertor converts the Direct Current output of the solar panel into Alternating Current for use in the electricity grid. These typically have a life time of 10-15 years [3]. Batteries, where used, will need to be replaced much more regularly.

Of course maintaining your panels is important. They will produce the most electricity if you keep them clean, and ensure that they remain at the best angle to receive maximum sunlight. Look after them, and they might still be powering your house in decades to come.

References:

  1. Wikipedia: Timeline of solar cells
  2. Renewable Energy World
  3. The Eco Experts
  4. Inhabitat: Worlds first modern solar panel still works after 60 years
  5. Clean Technica: Solar-panels-creating-electricity-for-much-longer-than-20-years
  6. Clean Technica: how-long-will-solar-panels-last?
  7. Solar Power Portal First UK grid connected PV system 95% efficient 20 years later
  8. Energy Informative

Image Credit: SuperHomes

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Comments

2 comments - read them below or add one

James55

James55Comment left on: 29 July 2016 at 12:28 pm

I bought my solar panels in 1997 and I am still using it and it works just fine. I know that it is expensive but, at the same time, it is worth it. It is convenient and it is good for the environment. It will last for long, believe me.

James

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Sims Solar Ltd

Sims Solar LtdComment left on: 28 July 2016 at 3:18 pm

Hi Alex, you mention perfromance of panels i.e., performance won't degrade by more than a specified percentage over 25 years, you don't mention the product warranty of panels which is typically less at 10-12 years. If there was water ingress or the junction box fell off or the bypass diodes failed then this would be a claim on the product warranty.

Since the claim will be against the manufacturer and most will want to independently assess your claim I suspect a warranty claim will be fruiteless and expensive. Even if the claim is upheld, the homeowner will still be faced with bearing the cost of scaffold and labour.

There is one manufacturer of panels that offers a 25yr combined product/performance and replacement warranty - SunPower. You may pay a bit more for the product but you get a no quibble warranty that outlives the FiT scheme.

Regards

Paul

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