I’ve been looking for the item about a 50 year old panel being discovered in a museum and found to be working fine. Can’t seem to turn it up.

I have seen no claim along the line of “after X years this panel quit making electricity”. No one seems to observed a “solar cliff” over which panels plunge after too many years. It might be out there past 50 years.

I don’t see any claims that the rate of output loss increases over years. In fact, what I’ve seen is that there can be a larger loss soon after a panel is put in service and then the loss slows down so that you end up with the ~half a percent per year.

Things are different in space. Lacking the protective filter provided by our atmosphere, orbiting panels tend to go downhill sooner.
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Heat.

Sometime over 20 years ago there was a test using Fresnel lenses to focus light on standard silicon panels (Arco brand). Some were cooked. Some survived. I bought 400 watts of the survivors to set up my first solar system around ’92. They were baked brown but still produced close to factory specs. Last I heard they’re still going strong (but no actual data).
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There was a 30 year study of a rather large array that was on line for a while. I failed to make a copy, assuming it would stay up, but it seems to be gone. What I recall is that they had a small (~2%) failure rate over the years. Delamination and/or connection corrosion – I don’t recall. Some of the panels were looking ratty after 30 years but still performing well. That 0.5% per year loss sort of decline.

Here’s what I’ve collected – I’m kinda dumping a mess here. I haven’t taken time to pull it all together in any sort of order.

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(I started a summary)

Center for Alternative Technology – UK
180 75W panels installed in 1997. In 2010 tested each panel. Average output after 13 years was 68.5W. 91% of original output. 0.7% per year loss.

LEE-TISO testing centre for PV components at the University of Applied Sciences of Southern Switzerland
10kW roof installation in 1982. Initial testing showed 10.7kW output. Tested in 2002. 11% loss after 20 years. 0.5% per year loss.

Atomic Energy and Alternative Energies Commission – France
9 45-watt Kyocera panels installed in 1992. After 20 years power production declined by 8.3%. 0.4% per year loss.

A single panel tested in Spain.
Manufactured in 1972 and rated at 37W. Tested in 2012 it produced 30W. A 19% loss in 40 years. 0.5% per year loss.

A single panel. US installed.
A 22W Arco panel installed in 1980. Tested in 2001 it produced 19 watts. A 14% loss in 21 years. 0.7% per year loss.

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(C&P)

What we found at CAT

Here at the Centre for Alternative Technology we installed our first integrated PV roof of 180 panels, rated at 75W peak output, in 1997. In spring 2010 we did some refurbishment on that roof and used the opportunity to inspect and test each of the panels. We performed a so-called “flash test” for each individual panel to establish how much of the original rated peak output of 75W the panel can still achieve. The result averaged to around 68.5W – only around 9% decrease over 13 years (0.7% per year). There were some differences between individual panels, but even the lowest performing panels still produced around 60W (20% decrease).

We did find some damage to some of the panels – there was laminate peeling off at the back and some colour changes (yellowing) at the front – but none of the 180 panels was in a condition that required replacement.

While 13 years is old for a PV roof in the UK, it is not a lot in terms of PV panel lifespan. Fortunately, there are some examples of very early PV roof installations which tell us more about the long-term durability and performance of solar electric panels.

Research from Switzerland: Still good after 20 years

The LEE-TISO testing centre for PV components at the University of Applied Sciences of Southern Switzerland installed Europe’s first grid-connected PV plant, a 10kW roof, in May 1982. They analysed the performance of the panels in 2002 andpublished the results in a scientific paper (Chianese et al, 2003). The PV plant was installed with 288 monocrystalline modules and an initial nominal plant power raring of 10.7kW, or an average of 37W peak rating per panel. Interestingly, when the panels were tested in 1983, the peak power output of the panels came to an average of 34W, 9% less than the initial rated peak output. This steep initial drop is normal – even with modern PV panels a loss of 5% over the first 12 months is not uncommon.

When the panels were tested in 2002, the average peak output of the panels was 32.9W – 11% lower than the nominal value in 1982 and only 3.2% lower than the measured value in 1983. In other words, between 1983 and 2002 the panels peak output had only degraded by around 0.2% per year since 1983 (0.5% per year against initial nominal rating).

Just as in the case of CAT’s PV roof, the LEE-TISO researchers found significant amounts of mechanical degradation of their panels. In 2002, 98% of their modules showed signs of yellowing, and 92% had issues with lamination peeling off. However, the impact of delamination on the overall plant performance was limited and only one single panel (less than 0.4%) was replaced.

Conclusion

Overall, the picture is very encouraging: Both our own experience at CAT and the research by LEE-TISO suggest that PV panel power output decreases by less than 1% per year. Panels do experience a significant amount of physical decay (yellowing, laminate peeling off) if they are exposed to the elements for 10 or 20 years, but the effect on their performance is limited. This suggests a PV installation should produce electricity for 30 years or longer.

http://info.cat.org.uk/questions/pv/life-expectancy-solar-PV-panels

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(Obviously not a native English speaker. Spanish U I believe)

It is a module of the year 1972 , ASI 16-2300 ARCH model.

This module consists of 35 monocrystalline silicon cells, has a rated capacity of 37 Wp, and during the test gives a power of 30 W. It really is to take your hat off and congratulate the manufacturer, as the panel is working perfectly, something unusual in the current scenario in which a number of products are manufactured with intentional weaknesses ( obsolescence ) in order that their lifetime does not extend beyond a few years. At the following link you can get the document with a study (much more comprehensive) on degradation of photovoltaic modules. Among the conclusions of this study, we note that:

After 20 years of operation, the degradation in most cases is between 5% and 8%

The facility used for testing is still fine after 29 years of operation

http://elfuturoeselectrico.blogspot.com/2012/09/que-tiempo-de-vida-tiene-una-placa-solar.html

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945-watt solar panels from Kyocera that were first installed in 1992 by Hespul were recently tested by Atomic Energy and Alternative Energies Commission (which is connected to the State Solar Research Institute INES — and the certification laboratory CERTISOLIS) to determine how much their performance had degraded.

The evaluators found that, after 20 years, the panels’ power production declined by only 8.3%. The electricity generation capacity of solar panels gradually decreases with time, of course, as the sun beats down on them. But the general projection is that they degrade a lot more in 20 years than this test shows — almost all evaluations of the levelized cost of energy (LCOE) of solar panels use a 20-year lifespan (which assumes they will be out of use after 20 years).

http://cleantechnica.com/2012/09/27/kyocera-solar-modules-show-only-8-3-performance-degradation-after-20-years/#Jk3KKBZHixmk57ch.99

0.4% per year.

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Two aspects of major importance for any solar module are energy conversion efficiency and product life. As a pioneer in multicrystalline silicon solar cell manufacturing technology with one of the highest conversion efficiency rates in the industry, and with a longer track record than the vast majority of market players, Kyocera points to a number of case studies from around the world which demonstrate its modules’ long product life and quality.

1. In 1984, Sweden’s first grid-connected photovoltaic system was built in Stockholm. Since its installation, the façade-mounted 2.1kW system has been continuously and reliably providing the residents of an apartment building with environmentally-friendly electricity. The modules’ average annual power generation performance is still reliable — with no significant change since the system was installed 27 years ago.

2. Also in 1984, Kyocera established its Sakura Solar Energy Center just outside of Tokyo. At the time, the Center was equipped with a 43kW solar power generating system which to this day continues to generate a stable amount of power for the facility.

3. In 1985, Kyocera made a donation of a 10kW solar power generation system to a small farming village with no electrical infrastructure located at an elevation of 2,600m (8,500ft) in Gansu Province, China. In 1993, the area received electrical infrastructure, and the solar modules were moved to a regional research facility for clean energy, where after more than 25 years, they are still producing consistent levels of electricity.

http://www.kyocerasolar.com/about-kyocera/kyocera-solar/news/?id=131
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The old Arco panel shown above was rated at 22 watts when brand new in 1980. It now produces about 19 watts. Not bad for 21 years in the sun!

http://www.otherpower.com/otherpower_solar_used.html
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How long does a solar panel?

One of the questions that arise who are considering the possibility of a PV system is the lifetime of photovoltaic modules (or solar panels, to understand). Currently, many manufacturers to ensure that your modules are delivered to least 80% of the rated output thereof after 20 years of operation. The question is not always easy to find photovoltaic installations with sufficient seniority to verify these figures. ‘s why I found this video particularly interesting: Some engineering students, embarked on an ambitious solar project that perhaps discuss another time, test a photovoltaic module with 40 yearsold.

It is a module of the year 1972 , ASI 16-2300 ARCH model. This module consists of 35 monocrystalline silicon cells, has a rated capacity of 37 Wp, and during the test gives a power of 30 W. It really is to take your hat off and congratulate the manufacturer, as the panel is working perfectly, something unusual in the current scenario in which a number of products are manufactured with intentional weaknesses ( obsolescence ) in order that their lifetime does not extend beyond a few years. At the following link you can get the document with a study (much more comprehensive) on degradation of photovoltaic modules. Among the conclusions of this study, we note that:

After 20 years of operation, the degradation in most cases is between 5% and 8%

The facility used for testing is still fine after 29 years of operation

Update (2012/10/28):

We found another story similar, a user by checking the operation of your photovoltaic panel purchased in 1980. In this case it is Arco Solar model 16-2000, an almost identical to the previous panel, except that it uses 33 cells instead of 35 and has a rated power of 33 Wp.

*Martin Holladay showing his panel with 30 years of use. Source: Green Building Advisor

The result is equally satisfactory: The panel continues to function in perfect condition after 30 years of service. From here, our heartfelt congratulations to both the manufacturer, as the pioneers who decided to bring this kind of technology 30 years ago.

Inverter manufacturers don’t know that. They offer 20 year warranties for their inverters.

The Hearth modified sine wave inverter I installed over 20 years ago is still working fine.

Solar panels lose, on average, around 0.5% per year.

The oldest panel is 50 years old and still working fine. But it has been stored out of sunlight for most of those years.

Why would it be such a big surprise if a cleantech site supports him?

Some of which is expounded on here: http://cleantechnica.com/2011/12/27/taking-a-closer-look-at-the-economic-benefits-of-solar/

Right now the average retail price of electricity in California is $0.129/kWh. At 3% inflation electricity will rise to $0.23/kWh in 20 years with an average of $0.17/kWh over the 20 years. At 5% inflation electricity will rise to $0.33/kWh with an average of $0.21/kWh.

In Los Angeles the Open Neighborhood program is currently installing solar at $4.22/watt. That creates electricity at $0.17/kWh with NO subsidies. Ignoring subsidies which would bring the price to owner under a dime and time of use pricing which makes daytime power very expensive, one breaks even for the first 20 years on raw cost alone at 3% inflation. Gets a sweet discount if we have 5% inflation.

There was some loss of panels due to delamination and connector corrosion. Edge seals and connector weather shielding are not rocket science. One would expect today’s panels to be greatly improved.

http://www.isaac.supsi.ch/isaac/pubblicazioni/Fotovoltaico/Final%20Report/rapporto%20finale%20-%20progetto%20eu%205fp%20-%20mean%20time%20before%20failure%20(mtbf)%202003.pdf

It’s time we started talking about solar panels being power producers for decades and decades. There’s no “solar cliff” over which performance falls after some number of years. Silicon solar panels are basically thin sheets of rock underneath a pane of glass.

Pay them off at grid parity in a few years and then enjoy many decades of almost free electricity. Solar is a very wise investment.