Yes, Dr. Ossenbrink is a recognized expert in PV module testing, but even experts make mistakes (as Climategate demonstrates). Assessing module durability, reliability, and power degradation is a very complex subject. For example, Dr. Ossenbrink wrote a paper in 2004 ( http://re.jrc.ec.europa.eu/solarec/publications/osaka_mqt12.pdf ), showing 54% of new module types fail in initial qualification testing (How many modules have been manufactured for more than 10-years and have all the kinks worked out?). But, of course, standard module qualification test results (including from accelerated testing) cannot be used to obtain or infer a product lifetime, as this NREL study demonstrates: http://www.nrel.gov/pv/performance_reliability/pdfs/osterwald_pip_review_2008.pdf

Here is an article that touches upon the difficulties in predicting service life for modules:

http://www.renewableenergyworld.com/rea/news/article/2009/12/pv-durability-and-reliability-issues

So, yes, this subject is far from settled, and, yes, it has major implications for LCOE or ROI calculations for PV systems.

Finally, regarding whether new modules are better than the old, here is one more (disturbing) study by ASU:

http://www.pv-tech.org/images/uploads/pdfs_ed_1/PVI-04.pdf

The conclusion: “The failure analysis of the qualification test results of ASU-PTL indicates a large increase in the failure rates for the 2005-2007 period as compared to the 1997-2005 period.”

Here is an example of the risks: “REC to Recall All of Its Solar Panels From 2008: Report:” http://www.greentechmedia.com/green-light/post/rec-to-recall-all-of-their-solar-panels-from-2008-report/

REC’s customers are very lucky that REC is a reputable company that is still in business. Because another company is suppressing the results from a long-term degradation study (which are indicating a likely violation of warranty) or various other system failure mechanisms, and has crafted a warranty language that allows them to blame module failure on insects (no kidding!). Buyer beware!

Secondly, there is an essential difference between the your studies and the assertions made by the Institute for Energy. Those studies examine panels that are now nearly 30 years old. The Energy Institute is taking new products – with whatever improvements 25 more years of research and development bring – and subjecting them to accelerated heat and weather simulations. It is an attempt to provide longevity testing for new panels rather than basing assumptions about today’s products with statistics gathered for products manufactured in the 1980′s. And even those panels only degraded roughly 5% over 20 years.

What do you think?

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

http://re.jrc.ec.europa.eu/solarec/publications/osaka_lifetime.pdf

Thin-film module failure and degradation, of course, are much more common and much more severe.