Perhaps the most provocative presentation given on the conference's first day came from Uwe Hupach of the TUV Rheinland Group, a certification house. He showed a slide showing a distribution of power deviation in a sample of several hundred PV modules from global manufacturers. The theme was how to mitigate risk factors that decrease overall power generation from a PV plant by implementing smarter testing and monitoring methods.
Sorry for the fuzzy quality. I took the picture using my iPhone from halfway across the room. Here's the gist:
- Nominal power specified by the module mfrs is the black dotted line way to the right of the graph
- A large majority of the power deviations tested fell under the nominal power level. My expectation for most electronic devices is that there should be a normal distribution of tested values above and below the spec.
- I was suprised at how high the percentage is of tested modules that were more than 10% below the nominal specified value. If you consider the total contribution level of PV installations worldwide (several tens of GW), a ten percent degradation in performance is a huge amount of lost production.
- The test was conducted on a random sampling of modules without mfr knowledge. When tests were conducted with the mfrs prior knowledge, and they submitted modules for the test, the distribution was normal.
- The question was asked about a similar test for inverter performance. TUV has not conducted such a study yet.
Let me know what you think. Are you surprised by this? Is it just par for the course in a growing industry with new players and vague standards? What does this say about the need for rigorous test and measurement practices? Please leave a comment.
Sorry for the fuzzy quality. I took the picture using my iPhone from halfway across the room. Here's the gist:
- Nominal power specified by the module mfrs is the black dotted line way to the right of the graph
- A large majority of the power deviations tested fell under the nominal power level. My expectation for most electronic devices is that there should be a normal distribution of tested values above and below the spec.
- I was suprised at how high the percentage is of tested modules that were more than 10% below the nominal specified value. If you consider the total contribution level of PV installations worldwide (several tens of GW), a ten percent degradation in performance is a huge amount of lost production.
- The test was conducted on a random sampling of modules without mfr knowledge. When tests were conducted with the mfrs prior knowledge, and they submitted modules for the test, the distribution was normal.
- The question was asked about a similar test for inverter performance. TUV has not conducted such a study yet.
Let me know what you think. Are you surprised by this? Is it just par for the course in a growing industry with new players and vague standards? What does this say about the need for rigorous test and measurement practices? Please leave a comment.
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