On 01/10/2012 08:10, harry wrote:
On Sep 30, 7:26 pm, Andy wrote:
On 29/09/2012 08:05, harry wrote:

Well no doubt you can provide statistics regarding maintenance costs
of wind turbines?
And a replacement inverter is not a maintenance cost, it's breakdown.
I haven't heard of a single invertor failure yet.
But unlike you, I can provide written evidence instead of backyard
theoretics.

http://www.pvmips.org/publications/017.pdf

In case you don't understand, it means in 20 years there is a 96.5%
chance there will be no problem with a modern inverter. As mine is
installed in an ideal situation (ie cool, dry and dust free) I expect
it will be even more reliable than that.

Are we reading the same document?

"If an average inverter lifetime of 5 years is assumed,"

"However, it has been verified that approximately 66% PV inverters have
undergone troubles"

You may have mixed panel and inverter figures.

Andy

Quote:-
• High MTBF suggests a 20 years lifetime with
90% reliability
The significant reliability performance is a quite
important requirement for the PVSs. Because MIC
signifies that the inverter will be mounted tightly at back
of PV module under outdoors conditions such as high
temperature, variable humidity and so on. Therefore,
integrated AC module should endure all those
extraordinary burdens for implementing excellent
reliability. In order to satisfy sufficiently so high
reliability requirements because of basically 20 years
lifetime from PV module, a high efficiency and reliable
laboratory prototype of a compact low-power inverter
has been implemented. Experiment results show
maximum 96.5% efficiency through using reliable
components. At the same time optimized thermal
management provides the favorable operating
environment for the sake of enhancing the inverter
reliability. The purpose of thermal management is to
remove redundant heat from decisive heat component
without causing negatively effect on reliability of
adjacent components, and sequentially to robust the
system reliability.

http://en.wikipedia.org/wiki/MTBF

3.4 System reliability prediction
In order to achieve the high reliability of the MIC
system, film capacitor and special designed power
module including 6 CoolMOS + 6 SiC diodes
investigated technically by Infineon are selected for the
system design in view of the excellent electric
performance and reliability demonstration.
In order to predict the reliability of the MIC system,
MIL-HDBK-217F [13]; Bellcore TR-332 [17] and IEC
62380 [18] are recommended for the calculation
comparison as regarding the typical components
selection and practical operation temperature. For the
reliability prediction, the operation temperature of the
electronic component is an important influence factor,
and 60° operation temperature and 4642 operating hours
in the whole year are supposed.
MTBF [Years]
Figure 5: MTBF comparison using MIL-HDBK-217F,
TR-332 and IEC 62380
All above mentioned prediction models are often
used for the reliability prediction of the commercial
product. No matter what kind of prediction model will be
employed, MTBFmin=37 years could be observed in the
histogram. Besides, the average temperature of the PV
module located in Kassel is Tavg=24.1°C [19]. Thus,
according to the 10°C rule in reliability prediction: every
10°C decreasing will lead to the twice MTBF increasing,
and therefore MTBFavg (min)200 years.

I hope they know more about PV and MIC than English grammar.

--
Rod