The evaluation of measurement readings of ADLER Solar’s in-house database of over 40.000 PV modules built between 2008 to 2015 shows that tested thin film modules are clearly more susceptible to lesser performance rates than crystalline silicon ones. The results also make obvious that most degradation mechanisms are module inherent, read the cause for a capacity reduction lies primarily on the cell level.

Accordingly, PV systems with thin film modules offer great repowering potential and thus the chance to replace affected modules with new, more efficient ones. Since the repowered PV plant is only allowed to generate the previously recorded original rating to receive the agreed upon feed in tariff, we recommend using the freed-up space for a new PV system (up to 750 kW) to get the feed in tariff according to EEG 2017 in addition.

Interesting is also that there is no linear correlation between the size of micro cracks in crystalline silicon modules and the underperformance; rather, it is caused by many different factors. Noteworthy is as well that many PV modules with various, heavy micro cracks present an underperformance rate that lies below warranty value limits defined by manufacturers.

Securing quality levels of PV plants and performance optimisation have been a core competence of ADLER Solar for 10 years by now. We will continue to examine the quality of PV modules and differences between various crystalline silicon modules as well in future projects. A separate assessment of new modules when it comes to incoming goods inspections is on the list as well.

If you are interested, we would be happy to provide further information and detailed results of the evaluation.


“Always downwards, never up!”

Martin Schachinger, founder and CEO of our long-standing partner pvXchange, regularly writes a market commentary which is being published on the website of pv magazine a.o..

Read his December contribution here where the PV expert looks back to last year and gives a forecast of prices developments for 2018.