[RE-wrenches] MTBF

[Bob-O Schultze]

Holt and All,
this is one of those places where this forum can save everyone a lot  
of grief. When a potentially game-changing product like the Enphase  
comes out with an obvious Marketing BS statement like 10 years MTBF,  
we all need to share out experiences with the product. Got failures?  
How many and how long in service? What geographic area (i.e. hot as in  
Arizona or cooler as in Wisconsin)?  Nothing like sunshine to effect  
product changes. ya know?
Bob-O
On Mar 26, 2009, at 8:01 AM, <holtek at sbcglobal.net> wrote:

I am working on a residential project that seems perfect for the  
Enphase product (long array to interconnect point run). Researching  
the product, I came across one of their website videos (nicely done)  
claiming an "MTBF of 119 years" without any explanation as to what  
that actually means - that is - how did they arrive at that assumption/ 
prediction. I googled "mean time between failures".  Got this - http://www.ptsdcs.com/whitepapers/57.pdf 
   - a white paper that briefly explains different methods to predict  
or assume system and or component failures/reliability. Interesting.  
The conclusion of this white paper:
MTBF is a “buzz word” commonly used in the IT industry. Numbers are  
thrown around without an

understanding of what they truly represent. While MTBF is an  
indication of reliability, it does not represent

the expected service life of the product. Ultimately an MTBF value is  
meaningless if failure is undefined and

assumptions are unrealistic or altogether missing. (emphasis mine).

So my question is this: Are any manufacturers that use MTBF as a  
selling point willing to disclose how these values were obtained? Not  
picking on Enphase....I will contact them with to ask. IMHO, with the  
new stuff that will be thrown at us over the coming years, we should  
expect real numbers from anyone using MTBF to tout their stuff.

Stepping off soap box.

Holt E. Kelly
Holtek Fireplace & Solar Products
500 Jewell Dr.
Waco TX. 76712
254-751-9111
www.holteksolar.com

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