pV panel degradation over time-some actual data

here's the important bit of the abstract (my bold)

Published data on photovoltaic (PV) degradation measurements were aggregated and re‐examined. The subject has seen an increased interest in recent years resulting in more than 11 000 degradation rates in almost 200 studies from 40 different countries. As studies have grown in number and size, we found an impact from sampling bias attributable to size and accuracy. Because of the correlational nature of this study we examined the data in several ways to minimize this bias. We found median degradation for x‐Si technologies in the 0.5–0.6%/year range with the mean in the 0.8–0.9%/year range.

So they had some dreadful panels, dragging the mean down. 0.6%/year gives a drop in output of 12% over 20 years.

Cheers

Greg Locock


New here? Try reading these, they might help FAQ731-376

Sounds much more like what sites I'm aware of have experienced rather than the very "authoritative" pronouncement of 100% loss over 20 years or some such that was postulated here a year or so ago.

I have a set of panels that are now 9 years old, they produced 3kw when brand new. Now just after cleaning them I will get 2900watts on a sunny day.
Is this an acceptable loss?
B.E.

You are judged not by what you know, but by what you can do.

That works out to 0.38% loss/yr, which is in the "high quality" group from the article.

TTFN (ta ta for now)
I can do absolutely anything. I'm an expert! faq731-376 forum1529 Entire Forum list

IRstuff,
So based on your reply that is an acceptable number. Good to know, not good that they degrade. Based on the KWhour total they have now paid back about a quarter of their cost, and the service life is based on 25 years.
B.E.

You are judged not by what you know, but by what you can do.

In my opinion, unless you get some amazing politically inspired feed in tariff, the economics of pV on an on-grid house are not compelling. . My on-grid installation has a crude payback of 7 years. That's something like a 14% return after tax, which even though I am a stock picking guru (in my dreams), is rather better than I usually manage. however it is entirely dependent on the FiT, and I doubt that will head anywhere except down over the years.

Of course for my off-grid house the bliss of not having to run the diesel gennie for 8 months of the year is sufficient in itself.


Cheers

Greg Locock


New here? Try reading these, they might help FAQ731-376